title: Voice over IP in the Local Exchange: A Case Study

abstract:
  There have been a small number of cost studies of Voice over IP (VoIP) in the
academic literature. Generally, they have been for abstract networks, have not
been focused on the public switched telephone network, or they have not
included the operating costs. This paper presents the operating cost portion of
our ongoing research project comparing circuit-switched and IP network costs
for an existing local exchange carrier.
  We have found that (1) The operating cost differential between IP and circuit
switching for this LEC will be small; and (2) A substantial majority of a
telco's operating cost lies in customer service and outside plant maintenance,
which will be incurred equally in both networks in a pure substitution
scenario. Thus, the operating cost difference lies in the actual cost
differences of the switching technologies. This appears to be less than 10%-15%
of the total operating cost of the network. Thus, even if the cost differences
for substitute services were large, the overall impact on the telco's financial
performance would be small. But IP has some hidden benefits on the operations
side. Most notably, data and voice services could be managed with the same
systems infrastructure, meaning that the incremental operations cost of rolling
out new services would likely be much lower, since it would all be IP.


title:
Second-Level Digital Divide: Mapping Differences in People's Online
  Skills

abstract:
  Much of the existing approach to the digital divide suffers from an important
limitation. It is based on a binary classification of Internet use by only
considering whether someone is or is not an Internet user. To remedy this
shortcoming, this project looks at the differences in people's level of skill
with respect to finding information online. Findings suggest that people search
for content in a myriad of ways and there is a large variance in how long
people take to find various types of information online. Data are collected to
see how user demographics, users' social support networks, people's experience
with the medium, and their autonomy of use influence their level of user
sophistication.


title: United States v. Microsoft: A Failure of Antitrust in the New Economy

abstract:
  This paper analyzes the law and economics of United States v. Microsoft, a
landmark case of antitrust intervention in network industries. [abridged]


abstract:
  Networks Unplugged: Towards A Model of Compatibility Regulation Between
Information Platforms This Article outlines a basic model for regulating
interoperability between rival information platforms. In so doing, it insists
that antitrust, intellectual property, and telecommunications regulation all
must follow the same set of principles to facilitate competition between rival
standards where possible, mandating or allowing cooperation only where
necessary to facilitate competition within a standard when network-level
competition is infeasible. To date, the antitrust regime best approximates the
type of model I have in mind, but sound competition policy requires that
telecommunications regulation and intellectual property law follow its basic
principles as well.


title:
The Impact of Incentives in the Telecommunications Act of 1996 on
  Corporate Strategies

abstract:
  Rules are necessary to provide or shape the incentives of individuals and
organizations. This is particularly true when free markets lead to undesirable
outcomes. The Telecommunications Act of 1996 attempted to create incentives to
foster competition. Ambiguity as well as the timing of the Act has led to
delays in the clarification of rules and the rapid obsolescence of the
document. The paper presents the strategies that common carriers adopted to try
to tilt regulation in their favor, slow the entry of competitors, maintain
their market leadership, and expand into other segments. Some of the strategies
analyzed include lobbying efforts, court challenges, and lack of cooperation
with new entrants.


title: Higher-Order Pattern Complement and the Strict Lambda-Calculus

abstract:
  We address the problem of complementing higher-order patterns without
repetitions of existential variables. Differently from the first-order case,
the complement of a pattern cannot, in general, be described by a pattern, or
even by a finite set of patterns. We therefore generalize the simply-typed
lambda-calculus to include an internal notion of strict function so that we can
directly express that a term must depend on a given variable. We show that, in
this more expressive calculus, finite sets of patterns without repeated
variables are closed under complement and intersection. Our principal
application is the transformational approach to negation in higher-order logic
programs.


title:
E-Business and SMEs: Preliminary Evidence from Selected Italian
  Districts

abstract:
  The debate on the Information Society shows large agreement on the assumption
that the promised benefits will fully display only if the diffusion of ICTs and
the Internet will involve all the actors of the socio-economic system.
Accordingly, special emphasis is put on the participation of small and medium
enterprises (SMEs), but also on public administrations (PAs) as promoters and
catalysts of private initiatives. As for SMEs, public intervention concerns
both the promotion of fully competitive e-markets and the solution of market
failures. However, effective and efficient intervention requires specific
information on SMEs' approach to e-commerce, often depending upon specific
sector and local condition and in most cases still lacking. In order to
identify the need and the scope for public intervention, the paper focuses on a
peculiar SMEs-intensive productive environment: the manufacturing industrial
district, which traditionally constitutes an examples of winning SMEs' network,
characterised by common industrial culture and intense input-output
interactions. The paper presents empirical evidence from the Italian districts
of Como (textile industry) and Lumezzane (metalwork industry). The research
results show that pro-active entrepreneurs are creatively exploring the
opportunities offered by the Internet to promote their businesses. However, it
is also clear that the transition to the Internet economy still involves a
reduced percentage of potential participants, and that institutional actions
are needed in order to foster a larger participation.


title: Indicators of Independence in Regulatory Commissions

abstract:
  Independent regulatory commissions such as the Federal Communications
Commission (FCC) must produce policies that reflect technical expertise, legal
precedent, and stakeholder input. Given these situational imperatives, how does
the FCC implement independence in its decision-making? This research explicates
some of the underlying rules, resources, and relationships within the
environment in which the agency is embedded that influence agency work
practices to operationalize independence. Research such as this may be helpful
in the creation of new, or for assessment of existing, regulatory commissions,
but only if great attention is paid not only to institutional structure, but
also to the practice of staff in the agency.


title: ICANN and Antitrust

abstract:
  The Internet Corporation for Assigned Names and Numbers (ICANN) is a private
non-profit company which, pursuant to contracts with the US government, acts as
the de facto regulator for DNS policy. ICANN decides what TLDs will be made
available to users, and which registrars will be permitted to offer those TLDs
for sale. In this article we focus on a hitherto-neglected implication of
ICANN's assertion that it is a private rather than a public actor: its
potential liability under the U.S. antitrust laws, and the liability of those
who transact with it. ICANN argues that it is not as closely tied to the
government as NSI and IANA were in the days before ICANN was created. If this
is correct, it seems likely that ICANN will not benefit from the antitrust
immunity those actors enjoyed. Some of ICANN's regulatory actions may restrain
competition, e.g. its requirement that applicants for new gTLDs demonstrate
that their proposals would not enable competitive (alternate) roots and ICANN's
preventing certain types of non-price competition among registrars (requiring
the UDRP). ICANN's rule adoption process might be characterized as
anticompetitive collusion by existing registrars, who are likely not be subject
to the Noerr-Pennington lobbying exemption. Whether ICANN has in fact violated
the antitrust laws depends on whether it is an antitrust state actor, whether
the DNS is an essential facility, and on whether it can shelter under
precedents that protect standard-setting bodies. If (as seems likely) a private
ICANN and those who petition it are subject to antitrust law, everyone involved
in the process needs to review their conduct with an eye towards legal
liability. ICANN should act very differently with respect to both the UDRP and
the competitive roots if it is to avoid restraining trade.


title:
Out of the Loop: Problems in the development of next generation
  community networks

abstract:
  Drawing on an ongoing longitudinal research study, we discuss problems in the
development of five next generation community networking projects in central
New York. The projects were funded under a state program to diffuse broadband
technologies in economically depressed areas of the state. The networks are
technologically complex and entail high costs for subscribers. The political
economy of the development process has biased the subscriber base toward the
resource rich and away from the resource poor, and toward tried-and-tested uses
like Internet and intra-organizational connectivity and away from
community-oriented uses. These trends raise troubling questions about network
ontology and function, and about the relation between the network and its
physical host community. The need for appropriate social policy, and new
planning practices, is argued to effect desired change.


title: Coase's Penguin, or Linux and the Nature of the Firm

abstract:
  The paper explains why open source software is an instance of a potentially
broader phenomenon. Specifically, I suggest that nonproprietary peer-production
of information and cultural materials will likely be a ubiquitous phenomenon in
a pervasively networked society. I describe a number of such enterprises, at
various stages of the information production value chain. These enterprises
suggest that incentives to engage in nonproprietary peer production are trivial
as long as enough contributors can be organized to contribute. This implies
that the limit on the reach of peer production efforts is the modularity,
granularity, and cost of integration of a good produced, not its total cost. I
also suggest reasons to think that peer-production can have systematic
advantages over both property-based markets and corporate managerial
hierarchies as a method of organizing information and cultural production in a
networked environment, because it is a better mechanism for clearing
information about human capital available to work on existing information
inputs to produce new outputs, and because it permits largers sets of agents to
use larger sets of resources where there are increasing returns to the scale of
both the set of agents and the set of resources available for work on projects.
As capital costs and communications costs decrease in importance as factors of
information production, the relative advantage of peer production in clearing
human capital becomes more salient.


title: Internet Attacks: A Policy Framework for Rules of Engagement

abstract:
  Information technology is redefining national security and the use of force
by state and nonstate actors. The use of force over the Internet warrants
analysis given recent terrorist attacks. At the same time that information
technology empowers states and their commercial enterprises, information
technology makes infrastructures supported by computer systems increasingly
accessible, interdependent, and more vulnerable to malicious attack. The
Computer Security Institute and the FBI jointly estimate that financial losses
attributed to malicious attack amounted to $378 million in 2000. International
Law clearly permits a state to respond in self-defense when attacked by another
state through the Internet, however, such attacks may not always rise to the
scope, duration, and intensity threshold of an armed attack that may justify a
use of force in self-defense.
  This paper presents a policy framework to analyze the rules of engagement for
Internet attacks. We describe the state of Internet security, incentives for
asymmetric warfare, and the development of international law for conflict
management and armed conflict. We focus on options for future rules of
engagement specific to Information Warfare.
  We conclude with four policy recommendations for Internet attack rules of
engagement: (1) the U.S. should pursue international definitions of "force" and
"armed attack" in the Information Warfare context; (2) the U.S. should pursue
international cooperation for the joint investigation and prosecution of
Internet attacks; (3) the U.S. must balance offensive opportunities against
defensive vulnerabilities; and (4) the U.S. should prepare strategic plans now
rather than making policy decisions in real-time during an Internet attack.


title:
National Information Infrastructure Development in Canada and the U.S.:
  Redefining Universal Service and Universal Access in the Age of
  Techno-Economic Convergence

abstract:
  This exploratory and descriptive research compares the policy-making
processes and policy recommendations regarding universal service and universal
access developed by the U.S. National Information Infrastructure Advisory
Council (NIIAC) and the Canadian Information Highway Advisory Council (IHAC) in
conjunction with related federal government agencies. Created in 1993 and 1994,
respectively, the Councils were charged with "bringing forward" the concepts of
universal service and universal access to adjust to the effects of
deregulation, new and converged Information and Communication Technologies
(ICTs), and neo-liberal economic competition and globalization that included
acknowledging the private sector as the primary creator of the Information
Highway.This qualitative study used as its methodology organizational, policy,
narrative, and discourse analyses to create a picture of what universal service
and universal access were and what they became in the hands of NIIAC, IHAC. The
U.S. had started with a more clearly defined universal service tradition than
Canada, and undertook a more complex policy-making process with more
experienced personnel. It was also clear that IHAC had in many ways followed
the U.S. model and arrived at many similar recommendations as NIIAC. Because of
the inevitability of technical, economic, and social change related to the
Information Highway, no definitive outcome to the Universal Service and
Universal Access "story" can be determined. Because the Canadian government did
not follow up on some of IHAC's most crucial recommendations, the Canadian
Information Highway "story," in particular, has been left less complete than
that of the U.S.


title:
Lead, Follow, or Go Your Own Way: Empirical Evidence Against
  Leader-Follower Behavior in Electronic Markets

abstract:
  Low search costs in Internet markets can be used by consumers to find low
prices, but can also be used by retailers to monitor competitors' prices. This
price monitoring can lead to price matching, resulting in dampened price
competition and higher prices in some cases. This paper analyzes price data for
316 bestselling, computer, and random book titles gathered from 32 retailers
between August 1999 and January 2000. In contrast to previous studies we find
no evidence of leader-follow behavior for the vast majority of retailers we
study. Further, the few cases of leader-follow behavior we observe seem to be
associated with managerial convenience as opposed to anti-competitive behavior.
We offer a methodology that can be used by future academic researchers or
government regulators to check for anti-competitive price matching behavior in
future time periods or in additional product categories.


title:
Pricing and Network Externalities in Peer-to-Peer Communications
  Networks (Draft)

abstract:
  This paper analyzes the pricing of transit traffic in wireless peer-to-peer
networks using the concepts of direct and indirect network externalities. We
first establish that without any pricing mechanism, congestion externalities
overwhelm other network effects in a wireless data network. We show that
peering technology will mitigate the congestion and allow users to take
advantage of more the positive network externalities. However, without pricing,
the peering equilibrium breaks down just like a bucket brigade made up of
free-riding agents. With pricing and perfect competition, a peering equilibrium
is possible and allows many more users on the network at the same time.
However, the congestion externality is still a problem, so peering organized
through a club may be the best solution.


title:
Asymmetric Regulation on Steroids: U.S. Competition Policy and Fiber to
  the Home

abstract:
  Fiber to the Home (FTTH) describes a set of emerging technologies with the
potential to affect competition in local access. On one hand, the high cost of
deploying fiber to the residence suggests limitations on facilities-based
competition among FTTH networks. On the other hand, FTTH opens up new
possibilities for service-level competition, defined as the sharing of a single
network infrastructure by multiple higher-layer service providers, whether of
the same or different services. Yet technology is hardly an exogenous factor
that independently shapes future local access competition; the regulatory
environment also plays a key role. By shaping expectations about future
competitive requirements, current regulations influence network operators'
deployment choices among competing FTTH technologies, as well as design choices
made by vendors and standards bodies for technologies still under
development.The current regulatory approach to FTTH is far from consistent.
Network operators likely to deploy FTTH include Incumbent Local Exchange
Carriers (ILECs), incumbent cable operators, competitive access providers
(including CLECs), independent telephone companies, and municipalities. This
paper reviews the rules related to service-level competition that apply to each
of these categories. In essence, the paper finds that if current regulatory
trends continue, asymmetries in the regulation of service-level competition
will be on steroids by the time FTTH starts being more commonly deployed.
Current regulatory requirements are either non-existent, or extremely detailed
and technology- and service- specific (e.g. UNEs). We argue that neither of
these approaches is likely to achieve the desired result for FTTH, given the
current state of flux in emerging FTTH technology.


title:
Electronic Access to Information and the Privacy Paradox: Rethinking
  :'Practical Obscurity'

abstract:
  This article addresses the U.S. Supreme Court's central purpose formulation
in Reporters Committee v. Department of Justice under the federal Freedom of
Information Act. By examining all lower federal court opinions interpreting
Reporters Committee and by analyzing the effects of the Court's opinion on the
implementation of the FOIA, the paper finds that the Court's opinion has
greatly narrowed the scope of the FOIA and limited the power of EFOIA to
democratize electronic information. To assist in remedying the damage to the
public interest in freedom of information, the author urges judicial
consideration of a Privacy Act case, Tobey v. NRB, that more subtly treats
information collected by government about individuals. The paper concludes that
the Privacy Act demonstrates clearly that information, particularly
computerized databases, can not be treated categorically for purposes of
access.


title: The Internet and Community Networks: Case Studies of Five U.S. Cities

abstract:
  This paper looks at five U.S. cities (Austin, Cleveland, Nashville, Portland,
and Washington, DC) and explores strategies being employed by community
activists and local governments to create and sustain community networking
projects. In some cities, community networking initiatives are relatively
mature, while in others they are in early or intermediate stages. The paper
looks at several factors that help explain the evolution of community networks
in cities:
  1) Local government support; 2) Federal support 3) Degree of community
activism, often reflected by public-private partnerships that help support
community networks.
  In addition to these (more or less) measurable elements of local support, the
case studies enable description of the different objectives of community
networks in different cities. Several community networking projects aim to
improve the delivery of government services (e.g., Portland and Cleveland),
some have a job-training focus (e.g., Austin, Washington, DC), others are
oriented very explicitly toward community building (Nashville, DC), and others
toward neighborhood entrepreneurship (Portland and Cleveland).
  The paper ties the case studies together by asking whether community
technology initiatives contribute to social capital in the cities studied.


title: Policy for access: Framing the question

abstract:
  Five years after the '96 Telecommunications Act, we still find precious
little local facilities-based competition. In response there are calls in
Congress and even from the FCC for new legislation to "free the Bells."
However, the same ideology drove policy, not just five years ago, but also
almost twenty years back with the first modern push for "freedom," namely
divestiture.
  How might we frame the question of policy for local access to engender a more
fruitful approach? The starting point for this analysis is the network--not
bits and bytes, but the human network. With the human network as starting
point, the unit of analysis is the community--specifically, the individual in a
tension with community. There are two core ideas.
  The first takes a behavioral approach to the economics--and the relative
share between beneficial chaos and order, in economic affairs, becomes
explicit.
  If the first main idea provides a conceptual base for open source, the second
core idea distinguishes open source from open design, ie at the information
'frontier' we push forward.
  The resulting policy frame for access is worked out in the detailed, concrete
steps of an extended thought experiment. A small town setting (Concord,
Massachusetts) grounds the discussion in the real world. The purpose overall is
to stimulate new thinking which may break out of the conundrum where periodic
rounds to legislate 'freedom' produce the opposite, recursively. The ultimate
aim is better fit between our analytically-driven expectations and economic
outcomes.


title: Realspace Sovereigns in Cyberspace: The Case of Domain Names

abstract:
  In this piece, we take up the case of the domain name system as an example of
challenges and solutions for realspace sovereigns in cyberspace. First, we
analyze the 'in rem' provision of the US Anticybersquatting Consumer Protection
Act (ACPA), which purports to expand the scope of the ACPA to encompass
disputes with little direct connection with the United States. In reality,
there exist no cases of foreign cybersquatting as to which the 'in rem'
provision will be both applicable and constitutional. Instead the ACPA 'in rem'
provision is notable primarily for its aggressive assertion of jurisdiction,
leading us to consider the (often overlooked) role of realspace sovereigns in
the regulation of the domain names system. By mapping the logical control over
the domain names system-the distributed hierarchy that is the basis of the
system's design-onto realspace territory, the potential for sovereign
regulation of the system becomes apparent. We argue that the regulatory
significance of geography, and the essentially arbitrary nature of the present
territorial locations of the key components of the domain name system implies
the future segmentation of the domain name system, and the resulting dramatic
decrease in its value. Accordingly, we argue that realspace sovereigns (and
especially the United States) have strong interests in avoiding segmentation,
and thus must seek to coordinate the regulation of the system.


title: Civic Engagement among Early Internet Adopters: Trend or Phase?

abstract:
  This paper brings evidence to bear on the question of the long-term effects
of Internet diffusion on civic engagement in geographic communities. It draws
on findings from survey data collected in four U.S. towns and cities in fall
2000 where community computer networking is established. The study shows that
early adopters of the Internet are more likely to engage in civic activities
and to have higher levels of community involvement than later adopters.
Further, early adopters are more likely to use the Internet to increase their
community involvement and political participation. Later adopters in all four
sites show less involvement in their local community and less interest in
political activity and information, online or offline. These findings reinforce
those of the Kohut (1999) study showing that later adopters are less civic
minded and more interested than early adopters in consumer and commercial
applications, such as shopping and entertainment. The evidence in these four
sites is consistent with earlier findings in Blacksburg, Virginia (Kavanaugh,
2000; Patterson and Kavanaugh, 2001; Kavanaugh and Patterson, 2001) and other
studies of early innovation adopters (Rogers, 1983; Kohut, 1999; Valente, 1995,
among others). The results reported in this paper lend weight to the argument
that increases in civic engagement and community involvement are due primarily
to the behavior of early adopters, making such increases a phase, not a trend.
As later adopters come on line, use of the Internet for community involvement
or civic engagement decreases. In the long term, we can expect that Internet
access may have only a modest effect on community involvement and civic
engagement in geographic communities.


title: Value of Usage and Seller's Listing Behavior in Internet Auctions

abstract:
  In this paper, we aim to empirically examine the value of website usage and
sellers' listing behavior in the two leading Internet auctions sites, eBay and
Yahoo!Auctions. The descriptive data analysis of the seller's equilibrium
listing behavior indicates that a seller's higher expected auction revenue from
eBay is correlated with a lager number of potential bidders measured by website
usage per listing. Our estimation results, based on the logarithm
specifications of sellers' expected auction revenues and potential bidders'
website usage, show that in a median case, (i) 1 percent increase of the unique
visitors (page views) per listed item induces 0.022 (0.007) percent increase of
a seller's expected auction revenue; and (ii) 1 percent increase of sellers'
listings induces 1.99 (4.74) percent increase of the unique visitors (page
views). Since increased expected auction revenues will induce more listings, we
can infer positive feedback effects between the number of listings and website
usage. Consequently, Yahoo!Auctions, which has substantially less listings, has
greater incentives to increase listings via these feedback effects which are
reflected in its fee schedules.


abstract:
  "What Should be Hidden and Open in Computer Security: Lessons from Deception,
the Art of War, Law, and Economic Theory" Peter P. Swire, George Washington
University.
  Imagine a military base. It is defended against possible attack. Do we expect
the base to reveal the location of booby traps and other defenses? No. But for
many computer applications,a software developer will need to reveal a great
deal about the code to get other system owners to trust the code and know how
to operate with it.
  This article examines these conflicting intuitions and develops a theory
about what should be open and hidden in computer security. Part I of the paper
shows how substantial openness is typical for major computer security topics,
such as firewalls, packaged software, and encryption. Part II shows what
factors will lead to openness or hiddenness in computer security.
  Part III presents an economic analysis of the issue of what should be open in
computer security. The owner who does not reveal the booby traps is like a
monopolist, while the open-source software supplier is in a competitive market.
This economic approach allows us to identify possible market failures in how
much openness occurs for computer security.
  Part IV examines the contrasting approaches of Sun Tzu and Clausewitz to the
role of hiddenness and deception in military strategy. The computer security,
economic, and military strategy approaches thus each show factors relevant to
what should be kept hidden in computer security. Part V then applies the theory
to a range of current legal and technical issues.


title:
Telecommunications and rural economies: Findings from the Appalachian
  region

abstract:
  This research investigates the relationship between telecommunications
infrastructure, economic conditions, and federal and state policies and
initiatives. It presents a detailed look at the telecommunications environment
of the Appalachian region, particularly focusing on broadband technologies. A
strong, positive association exists between telecommunications infrastructure
and economic status. The effects of federal and state universal service
policies are examined, as well as some of the ways states have leveraged their
own infrastructure to improve telecommunications capabilities in their region.
Other state and local telecommunications-related programs are noted.


title:
E PLURIBUS ENUM: Unifying International Telecommunications Networks and
  Governance

abstract:
  ENUM effectively bridges the telephone and Internet worlds by placing
telephone numbers from the ITU Rec. E.164 public telecommunication numbering
plan into the Internet Domain Name System (DNS) as domain names. ENUM
potentially presents significant public policy issues at both the domestic and
international levels. Ultimately, it should not matter whether ENUM is
approached as a telecommunications issue or an Internet issue because: (1) they
are becoming the same thing technically, and (2) they engage the same global
public interests. For the same reasons as apply to traditional
telecommunications, and even to the Internet itself, public oversight of ENUM
naming, numbering, and addressing resources is justified both by technical
necessity and the interests of consumer protection (particularly personal
privacy) and competition at higher service layers. A single, coordinated global
DNS domain for at least Tier 0 (the international level) of the ENUM names
hierarchy should be designated by public authorities. Many of the technical
characteristics and policy considerations relevant at the ENUM Tier 0 and 1
zones are also directly applicable to the Internet's IP address space and DNS
root (or Tier 0) zone - key shared elements of the Internet's logical
infrastructure. Despite the fundamentally international nature of the
Internet's logical infrastructure layer, and the purported privatization of
administration of its IP address space and the DNS, Internet governance is not
yet truly international. The ENUM policy debate illustrates the need for
authoritative international public oversight of public communications network
logical infrastructure, including that of traditional telecommunications, the
Internet, and ENUM.


title:
Is the Commercial Mass Media Necessary, or Even Desirable, for Liberal
  Democracy?

abstract:
  Is a commercial mass media, dependent on the market for its sustenance,
necessary, or even desirable, for liberal democracy? Yochai Benkler has argued
that a decentralized, peer-to-peer system of communications and information is
both possible with digital technology and preferable to a system based on
commercial mass media. He has contended in fact that the presence of
politically powerful, copyright-rich mass media imposes significant barriers to
the development of peer-to-peer information-sharing networks. In contrast, I
have argued that the commercial mass media play an important, and perhaps even
vital, role in liberal democracy by galvanizing public opinion, serving as a
watchdog against government and corporate wrongdoing, agenda-setting (which
enables public discourse), and serving as a relatively trustworthy source of
information. This paper seeks to push the ball forward on this issue. It first
isolates and enumerates the contributions that the commercial mass media are
said to make towards liberal democracy. It then briefly assesses the extent to
which the commercial mass media actually fulfills these constitutive functions.
It then asks whether alternative institutions might serve some or all of these
functions just as well or better. In so doing, it looks both to the past and
the future. First, it examines the political party-supported press that thrived
in the United States through much of the 19th century. Second, it examines
government-funded mass media. Third, it looks, skeptically, at possibilities
for peer-to-peer sharing of information and opinion in the digital network
environment. I conclude that, despite the weaknesses of commercial mass media,
an information policy suitable to liberal democracy should include a plurality
of types of voices, including commercial mass media.


title:
Open Access to Monopoly Cable Platforms Versus Direct Access To
  Competitive International Telecommunications Satellite Facilities: A Study In
  Contrasts

abstract:
  In 1999, the FCC authorized direct access to INTELSAT, allowing INTELSAT's
U.S. customers and competitors to bypass INTELSAT's U.S. retail affiliate
(COMSAT), and to take satellite capacity at wholesale prices directly from
INTELSAT. This policy was modeled in many respects on the access and unbundling
requirements applicable to domestic incumbent local exchange carriers (ILECs)
under the Telecommunications Act of 1996. At the same time, incumbent domestic
cable TV system operators have not been required to provide wholesale open
access to competitive Internet Service Providers (ISPs) seeking to provide
residential broadband Internet service through existing proprietary cable
facilities. Yet the policy arguments favoring open access to incumbent domestic
cable systems appear to be stronger than those favoring direct access to
INTELSAT.
  For example, it may be fairly debated whether entrenched cable system
operators are now positioned to unfairly leverage their dominance in the
multichannel video programming distribution (MVPD) market to thwart competition
in the broadband ISP market, as some cable open access advocates assert. In
contrast, it is clear that no analogous issues of tying were implicated by
INTELSAT in 1999, when its position in the international telecommunications
market was substantially nondominant and, in any event, it had no new product
to tie to its established offerings. Similarly, while it may be debated whether
or not a cable plant is a bottleneck facility that gatekeeps broadband Internet
for many residential users, it is beyond cavil that INTELSAT in 1999 controlled
virtually no such bottleneck facilities.


title:
Competition and Globalization Brazilian Telecommunications Policy at
  Crossroads

abstract:
  The current pattern of competition in the Brazilian telecommunications market
was defined by a regulatory reform implemented in the second half of the
nineties. The telecommunications regulatory reform discussed in the paper
promoted the privatization of Telebras System and fostered competition in the
Brazilian market under the stricted supervision of the new regulator Anatel.
Notwithstanding, the regulatory Brazilian scheme is at a crossroads. From 2002
on an open market approach will be implemented in telecom arena. We analyse the
main aspects of those change, from the firms perspective and also in a broad
scenario under influence of the World Trade Organization system


title:
Assessing the Effectiveness of Section 271 Five Years After the
  Telecommunications Act of 1996

abstract:
  A major goal of the Telecommunications Act of 1996 is to promote competition
in both the local exchange and long distance wireline markets. In section 271
Congress permitted the Bell Operating Companies (BOCs) to enter the long
distance market only if they demonstrate to the FCC that they have complied
with the market-opening requirements of section 251. This paper examines the
logic behind section 271, to determine if it is a reasonable means of achieving
increased competition in both the local and long distance markets, given the
technical characteristics of the industry and the legal and informational
constraints on regulators who must ensure compliance. It also provides an
update on the extent of competitive entry in the local exchange market five
years after enactment of the Act.
  In this paper we examine a variety of schemes for ensuring BOC compliance
that Congress could have used. Given the characteristics of the industry and
the limitations on regulators' ability to observe BOC's efforts, we determine
that the use of a prize such as BOC entry into long distance is a superior
incentive mechanism. We further determine that conditioning a BOC's long
distance entry on its demonstrating compliance with section 251 is a logical
method of protecting the long distance market against a BOC discriminating
against long distance competitors once it has gained entry. The statistical
evidence we look at, using data we have collected on ILEC lines sold to CLECs
for POTS services, appears to confirm that section 271 has thus far been
effective in ensuring compliance.


title: CyberCampaigns and Canadian Politics: Still Waiting?

abstract:
  The early election call in the fall of 2000 provided the perfect opportunity
to study the impact the Internet has had on election campaigning in Canada.
With the explosion of use the Net has seen since the 1997 general election,
Canadian federal parties stood at the threshold of a new age in election
campaigning. Pundits such as Rheingold (1993) have argued that the Internet
will provide citizens with a way to bypass traditional media and gain
unmediated access to each parties political message as well as providing a
forum for citizens to engage the parties, and each other in deliberative
debate.
  Through a longitudinal analysis of party web pages and telephone interviews
with party staffers, we analyze the role the Internet played in the election
campaigns of Canada's federal parties. Our findings indicate that the parties
are still focusing on providing online features that talk at the voter instead
of engaging them in any type of meaningful discourse. Most of these sites were
exceptionally similar in their structure and in the type of content they
provided. Generally, these sites served as digital archives for campaign
material created with other media in mind and despite the multimedia
capabilities of the Internet, these sites tended to be overwhelmingly text
oriented. In line with Stromer-Galley's (2000) discussion of why candidates in
the U.S. avoid online interaction, we also argue that little incentive exists
to motivate parties to engage in any meaningful interaction with voters online.


title:
'Negotiated Liberalization': Stakeholder Politics and Communication
  Sector Reform in South Africa

abstract:
  The paper examines the South African transition from apartheid to democracy
through the lens of the reform of the communication sector. Through a set of
participatory stakeholder consultative processes, the institutions of
broadcasting, telecommunications, print press, and state information agency
underwent reform in a process I refer to as 'negotiated liberalization.'


title:
The Influence of Policy Regimes on the Development and Social
  Implications of Privacy Enhancing Technologies

abstract:
  As privacy issues have gained social salience, entrepreneurs have begun to
offer privacy enhancing technologies (PETs) and the U.S. has begun to enact
privacy legislation.
  But "privacy" is an ambiguous notion. In the liberal tradition, it is an
individualistic value protecting citizens from intrusion into a realm of
autonomy. A feminist critique suggests that the social utility of privacy is to
exclude certain issues from the public realm. Sociologists suggest that privacy
is about identity management, while political economists suggest that the most
salient privacy issue is the use of personal information to normalize and
rationalize populations according to the needs of capital.
  While PETs have been developed for use by individual consumers, recently
developers are focusing on the business to business market, where demand is
stoked by the existence of new privacy regulations. These new laws tend to
operationalize privacy in terms of "personally identifiable information." The
new generation of PETs reflect and reify that definition. This, in turn, has
implications for the everyday understandings of privacy and the constitution of
identity and social life.
  In particular, this socio-technical practice may strengthen the ability of
data holders to rationalize populations and create self-serving social
categories. At the same time, they may permit individuals to negotiate these
categories outside of panoptic vision. They may also encourage public
discussion and awareness of these created social categories.


title: ICANN as Regulator

abstract:
  This paper tells the story leading to ICANN's selection of seven new Internet
top level domains in November 2000. In implementing proposals to expand the
name space, ICANN adopted an approach far different from Jon Postel's
lightweight proposals. ICANN staff, in setting the ground rules for considering
new gTLDs, emphasized that only a few applicants would be allowed in, and
imposed strict threshold requirements. Staff determined that the Board should
pick TLDs by looking at all relevant aspects of every proposal, and deciding
which ones presented the best overall combination of a variety of
incommensurable factors. Aspects of the resulting process were predictable:
Anyone familiar with the FCC comparative hearing process for broadcast licenses
can attest that this sort of ad hoc comparison is necessarily subjective,
lending itself to arbitrariness and biased application. Yet the process had
advantages that appealed to ICANN decision-makers. The Board members would be
free to take their best shots, in a situationally sensitive manner, at
advancing the policies they thought important. The approach allowed ICANN to
maintain the greatest degree of control. The end result, though, was a process
stunning in its arbitrariness, a bad parody of fact-bound, situationally
sensitive (rather than rules-based) decision-making.


title: Comparison of Wireless Standards-Setting --United States Versus Europe

abstract:
  When decisions about developing standards are left to individual firms, there
are many advantages including a flexible response to market evolution,
accommodation to rapid technology change, and avoidance of costly coordination.
However, the market process does not necessarily lead to compatible standards,
especially when there is no clear market dominator. Standards Institutions
generally facilitate better communication among market participants, which may
discourage early and/or primitive incompatible standards to emerge in the
market. However, expenditures on institutional standards-setting can lead to
diminishing returns, or even be counter-productive because institutional
standards usually take longer to produce and are slower to respond to
technology development. Government agencies can specify compulsory standards to
avoid incompatibility. In addition, governments can tie their policy on
standardization closely with their industrial, trade, and/or regulatory
policies. However, many exogenous factors handicap a government's effective
involvement. Government often fails to respond to the dynamics of technology
development and consumer demand, and to pick up the "right technology". This
study first discusses why two different models have emerged in the two regions.
It then examines outcomes and implications of the two models, including impacts
on domestic service deployment, global trade competition, technology
innovations, and strategies of multinational corporations. The goal is to
conduct an empirical comparison between the two contrasting models.


title:
Best Effort versus Spectrum Markets: Best Effort versus Spectrum
  Markets: The Cases of European MVNOs and (Ultra)Wideband Unlicensed Services

abstract:
  This paper compares two models for delivering broadband wireless services:
best effort vs. QoS guaranteed services. The 'best effort' services we refer to
in this paper are more commonly known as unlicensed wireless services, while
the 'Quality of Service guaranteed' services are more commonly referred to as
traditional landline telephony, as well as cellular telephone services of
either the second or third generation.
  This paper highlights the differing 'market' versus 'engineering'
philosophies implicit in alternative wireless service architectures.


title: The Next Frontier for Openness: Wireless Communications

abstract:
  For wireless communications, the FCC has fostered competition rather than
openness. This has permitted the emergence of vertically integrated end-to-end
providers, creating problems of reduced hardware innovation, software
applications, user choice, and content access. To deal with these emerging
issues and create multi-level forms of competition, one policy is likely to
suffice: a Carterfone for wireless, coupled with more unlicensed spectrum.


title: Leveraging Software, Advocating Ideology: Free Software and Open Source

abstract:
  This paper uses the software program Linux and the discourse around it in
order to examine how software programs can be used to articulate and defend
social and economic positions. Although I do not use the term "expression" in a
strict legal sense, I claim that in order to make policy decisions involving
software, it is important to understand how the functionality of software is
expressive. Another way to state this is that software programs like Linux are
socially meaningful through functionality and talk about functionality.
  In section I, I review some recent legal scholarship about software and
explain why understanding how embedded technical expression works is important
given the increasingly large role of software in governance. In section II, I
explore software construction as a combination of social and technical
practices. In section III, I describe some examples of meaning-making around
the software program Linux. In section IV I conclude with a short description
of why such analyses are important.


title:
Universal Service in times of Reform: Affordability and accessibility of
  telecommunication services in Latin America

abstract:
  By surveying the universal service policies in six Latin American countries,
this study explores the evolution of the concept during the rollout of the
telecommunication reform in the last decade. Country profiles and a set of
universal service indicators provide a frame for discussing issues of
accessibility and affordability of telephone service in the region. This study
found that the reconfiguration of national networks fostered by liberalization
policies offered risks and opportunities to achieve universal service goals.
The diversification of access points and services enhanced users choices but
price rebalancing and lack of Universal Service Obligations (USO) to target
groups with special needs depressed the demand and threatened to exclude
significant parts of the population. The situation requires the reformulation
of USO incorporating all technological solutions existing in the market, and
factors from the consumer-demand accounting for the urban-rural continuum, and
different social and economic strata. This study identifies the emergence of a
second generation of USO targeting some of these needs. However, more
competition and special tariff plans for the poor need to be incorporated to
the options available in the market.


title:
Standards and Intellectual Property Rights in the Age of Global
  Communication - A Review of the International Standardization of
  Third-Generation Mobile System

abstract:
  When the European Telecommunications Standards Institute (ETSI) selected a
radio access technology based on Wideband Code-Division Multiple Access
(WCDMA), sponsored by European telecommunications equipment manufactures
Ericsson and Nokia, for its third-generation wireless communications system, a
bitter dispute developed between ETSI and Qualcommm Inc. Qualcomm threatened to
withhold its intellectual property on the CDMA technology unless the Europeans
agreed to make the radio access technology backward compatible with cdmaOne,
Qualcomm's favored version of CDMA. A dispute over intellectual property rights
over key CDMA techniques also erupted between Ericsson and Qualcomm and both
filed patent infringement in US Court. The dispute halted the standards
activity and has troubled operators worldwide as well as the International
Telecommunications Union (ITU).


title:
Bigger May Not Be Better: An Empirical Analysis of Optimal Membership
  Rules in Peer-To-Peer Networks

abstract:
  Peer to peer networks will become an increasingly important distribution
channel for consumer information goods and may play a role in the distribution
of information within corporations. Our research analyzes optimal membership
rules for these networks in light of positive and negative externalities
additional users impose on the network. Using a dataset gathered from the six
largest OpenNap-based networks, we find that users impose a positive network
externality based on the desirability of the content they provide and a
negative network externality based on demands they place on the network.
Further we find that the marginal value of additional users is declining and
the marginal cost is increasing in the number of current users. This suggests
that multiple small networks may serve user communities more efficiently than
single monolithic networks and that network operators may wish to specialize in
their content and restrict membership based on capacity constraints and user
content desirability.


title: Is Patent Law Technology Specific?

abstract:
  Although patent law purports to cover all manner of technologies, we have
noticed recent divergence in the standards applied to biotechnology and to
software patents: the Federal Circuit has applied a very permissive standard of
obviousness in biotechnology, but a highly restrictive disclosure requirement.
The opposite holds true for software patents, which seems to us exactly
contrary to sound policy for either industry. These patent standards are
grounded in the legal fiction of the "person having ordinary skill in the art"
or PHOSITA. We discuss the appropriateness of the PHOSITA standard, concluding
that it properly lends flexibility to the patent system. We then discuss the
difficulty of applying this standard in different industries, offering
suggestions as to how it might be modified to avoid the problems seen in
biotechnology and software patents.


title:
Spectrum auctions, pricing and network expansion in wireless
  telecommunications

abstract:
  This paper examines the effects of licensing conditions, in particular of
spectrum fees, on the pricing and diffusion of mobile communications services.
Seemingly exorbitant sums paid for 3G licenses in the UK, Germany in 2000 and
similarly high fees paid by U.S. carriers in the re-auctioning of PCS licenses
early in 2001 raised concerns as to the impacts of the market entry regime on
the mobile communications market.
  The evidence from the GSM and PCS markets reviewed in this paper suggests
that market entry fees do indeed influence the subsequent development of the
market. We discuss three potential transmission channels by which license fees
can influence the price and quantity of service sold in a wireless market: an
increase in average cost, an increase in incremental costs, and impacts of sunk
costs on the emerging market structure.
  From this conceptual debate, an empirical model is developed and tested using
cross-sectional data for the residential mobile voice market. We utilize a
structural equation approach, modeling the supply and demand relationships
subject to the constraint that supply equals demand. The results confirm the
existence of a positive effect of license fees on the cost of supply. However,
we also find that higher market concentration has a positive effect on the
overall supply in the market, perhaps supporting a Schumpeterian view that a
certain degree of market concentration facilitates efficiency.


title: The Role of Institutions in the Design of Communication Technologies

abstract:
  Communication technologies contain embedded values that affect our society's
fundamental values, such as privacy, freedom of speech, and the protection of
intellectual property. Researchers have shown the design of technologies is not
autonomous but shaped by conflicting social groups. Consequently, communication
technologies contain different values when designed by different social groups.
Continuing in this vein, we show that the institutions where communication
technologies are designed and developed are an important source of the values
of communication technologies. We use the term code to collectively refer to
the hardware and software of communication technologies. Institutions differ in
their motivations, structure, and susceptibility to external influences. First,
we focus on the political, economic, social, and legal influences during the
development of code. The institutional reactions to these influences are
embodied in code. Second, we focus on the decision-making issues in the review
process for code. This process determines the code's content and affects the
dissemination of code through the decision whether to publicly release the
code. We found these factors vary by institution. As a result, institutions
differ in the values that they incorporate into code or communications
technologies.


title:
Efficient Choice, Inefficient Democracy? The Implications of Cable and
  Internet Access for Political Knowledge and Voter Turnout

abstract:
  This paper explains why, despite a marked increase in available political
information on cable television and the Internet, citizens' levels of political
knowledge have, at best, remained stagnant (Delli Carpini & Keeter, 1996).
Since the availability of entertainment content has increased too, the effect
of new media on knowledge and vote likelihood should be determined by people's
relative preferences for entertainment and information. Access to new media
should increase knowledge and vote likelihood among people who prefer news. At
the same time, it is hypothesized to have a negative effect on knowledge and
turnout for people who prefer entertainment content. Hypotheses are tested by
building a measure of Relative Entertainment Preference (REP) from existing NES
and Pew survey data. Results support the predicted interaction effect of media
environment (cable and/or Internet access) and motivation (REP) on political
knowledge and turnout. In particular, people who prefer entertainment to news
and have access to cable television and the Internet are less knowledgeable and
less likely to vote than any other group of people.


title:
Quality of service monitoring: Performance metrics across proprietary
  content domains

abstract:
  We propose a quality of service (QoS) monitoring program for broadband access
to measure the impact of proprietary network spaces. Our paper surveys other
QoS policy initiatives, including those in the airline, and wireless and
wireline telephone industries, to situate broadband in the context of other
markets undergoing regulatory devolution. We illustrate how network
architecture can create impediments to open communications, and how QoS
monitoring can detect such effects. We present data from a field test of
QoS-monitoring software now in development. We suggest QoS metrics to gauge
whether information "walled gardens" represent a real threat for dividing the
Internet into proprietary spaces.
  To demonstrate our proposal, we are placing our software on the computers of
a sample of broadband subscribers. The software periodically conducts a battery
of tests that assess the quality of connections from the subscriber's computer
to various content sites. Any systematic differences in connection quality
between affiliated and non-affiliated content sites would warrant research into
the behavioral implications of those differences.
  QoS monitoring is timely because the potential for the Internet to break into
a loose network of proprietary content domains appears stronger than ever.
Recent court rulings and policy statements suggest a growing trend towards
relaxed scrutiny of mergers and the easing or elimination of content ownership
rules. This policy environment could lead to a market with a small number of
large, vertically integrated network operators, each pushing its proprietary
content on subscribers.


title: Elusive Threats: Security Weaknesses of Commercial Cellular Networks

abstract:
  Commercial cellular telecommunications networks are routinely used as key
means of voice and data transport by both businesses and the Public. Despite
advances in encryption and other security measures, these commercial cellular
networks remain extremely vulnerable to malicious attacks and the loss of user
and data privacy and integrity. Such losses can result not only in mere
inconvenience, but in serious corporate and national security breaches. Because
of the potentially catastrophic nature of such security breaches, it behooves
cellular network operators, distributors, and users to explore these network
risk areas and mitigate them to the extent that current resources allow.


title:
Digital Arroyos: An Examination of State Policy and Regulated Market
  Boundaries in Constructing Rural Internet Access

abstract:
  This focused study on state-level policy and access patterns contributes to a
fuller understanding of how these invisible barriers work to structure access
and define rural communities. Combining both quantitative and qualitative data,
this study examines the role of geo-policy barriers in one of the largest and
most rural states in the nation.
  Expanded Area Service policies are state policies wherein phone customers can
expand their local calling area. Because useful Internet access requires a
flat-price connection, EAS policies can play a crucial role in connecting
citizens to one another. EAS policies (including Texas') tend to vary along
five dimensions (community of interest, customer scope, directionality, pricing
mechanism and policy scope). EAS policies that rely on regulated market
boundaries for definition can generate gross inequities in rural Internet
access. Interviews with Internet Service Providers in a case study of 25 rural
communities reveals that LATA and exchange boundaries, along with
geographically restricted infrastructure investments, curtail service provision
in remote areas. A statistical analysis of 1300 telephone exchanges, including
208 rural telephone exchanges in Texas reveals that the farther a community
lies from a metropolitan area the less likely they are to have reliable
Internet access


title:
The Consumer Product Selection Process in an Internet Age: Obstacles to
  Maximum Effectiveness & Policy Options

abstract:
  Intermediaries, like real estate agents, Consumer Reports, and Zagats, have
long helped buyers to identify their most suitable options. Now, the
combination of databases and the Internet enables them to serve consumers
dramatically more effectively. This article begins by offering a three-part
framework for understanding the evolving forms of selection assistance. It then
focuses on numerous potential obstacles that could prevent shoppers from
enjoying the full benefits of these developing technologies. While concluding
that adjustments to business strategies and the enforcement of existing laws
can effectively overcome most of these impediments, the article identifies
several areas where proactive government action may be desirable, such as to
prevent the emergence of anticompetitive entry barriers.


title: Prospects for Improving Competition in Mobile Roaming

abstract:
  The ability to make international roaming calls is of increasing importance
to customers in Europe. This contrasts with various complaints that retail
prices of roaming calls are rigid and excessive. The focus if the paper is on
wholesale roaming, which is the prime determinant of retail roaming prices. The
paper analyses the structural conditions of wholesale roaming markets that have
impaired incentives to competition, namely high combined market share of the
two leading GSM 900 operators combined with second mover disadvantages for new
entrant GSM 1800 operators, and demand externalities. The paper argues that a
number of developments are under way that are likely to modify this situation
in the future. With the introduction of SIM over-the-air programming, home
mobile operators will be able to direct customers to networks with the lowest
charges. As dual mode handsets become ubiquitous and as new entrant GSM 1800
operators reach nationwide coverage, second-mover disadvantages will disappear.
Given the relatively small roaming volumes that GSM 1800 operators currently
provide, they should have an incentive to lower charges in exchange for
preferred roaming status. On the demand side of wholesale roaming markets, it
will be the larger GSM 900 operators, and in particular those with a
pan-European footprint, that will ask for lower charges in exchange for
preferred roaming status. This could discriminate against mobile operators in
downstream retail markets that do not have a pan-European footprint and that
lack the bargaining power. However, arbitrage by roaming brokers, new entry and
wider geographical markets on the retail roaming level will work against this.


title: Digital Color Imaging

abstract:
  This paper surveys current technology and research in the area of digital
color imaging. In order to establish the background and lay down terminology,
fundamental concepts of color perception and measurement are first presented
us-ing vector-space notation and terminology. Present-day color recording and
reproduction systems are reviewed along with the common mathematical models
used for representing these devices. Algorithms for processing color images for
display and communication are surveyed, and a forecast of research trends is
attempted. An extensive bibliography is provided.


title: Computer Security: Competing Concepts

abstract:
  This paper focuses on a tension we discovered in the philosophical part of
our multidisciplinary project on values in web-browser security. Our project
draws on the methods and perspectives of empirical social science, computer
science, and philosophy to identify values embodied in existing web-browser
security and also to prescribe changes to existing systems (in particular,
Mozilla) so that values relevant to web-browser systems are better served than
presently they are. The tension, which we had not seen explicitly addressed in
any other work on computer security, emerged when we set out to extract from
the concept of security the set values that ought to guide the shape of
web-browser security. We found it impossible to construct an internally
consistent set of values until we realized that two robust -- and in places
competing -- conceptions of computer security were influencing our thinking. We
needed to pry these apart and make a primary commitment to one. One conception
of computer security invokes the ordinary meaning of security. According to it,
computer security should protect people -- computer users -- against dangers,
harms, and threats. Clearly this ordinary conception of security is already
informing much of the work and rhetoric surrounding computer security. But
another, substantively richer conception, also defines the aims and trajectory
of computer security -- computer security as an element of national security.
Although, like the ordinary conception, this one is also concerned with
protection against threats, its primary subject is the state, not the
individual. The two conceptions suggest divergent system-specifications, not
for all mechanisms but a significant few.


title:
Inventing E-Regulation in the US, EU and East Asia: Conflicting Social
  Visions of the Internet & the Information Society

abstract:
  This paper attempts to assess the international approach to Internet policy
in the context of distinctive socio-political frameworks evolving in the US,
the European Union (EU), and East Asia. The comparative review will develop a
set of underlying structural models of the Information Society particular to
each region, along with an analysis of their defining characteristics in
relation to one another. This examination demonstrates how each region, given
its regulatory legacy, has elected a different mix of good and bad
socio-political choices in public policy for the Internet. Despite the range
and diversity of paths to e-regulation suggested in these choices, none
adequately addresses the underlying issue of how to promote an innovative
society that is open to broad social participation. The paper evaluates
principal weaknesses in these regional models of Internet policy and argues the
need for re-conceptualizing the cultural, political and economic approach to
the new information space of the Internet.


title: The temporal calculus of conditional objects and conditional events

abstract:
  We consider the problem of defining conditional objects (a|b), which would
allow one to regard the conditional probability Pr(a|b) as a probability of a
well-defined event rather than as a shorthand for Pr(ab)/Pr(b). The next issue
is to define boolean combinations of conditional objects, and possibly also the
operator of further conditioning. These questions have been investigated at
least since the times of George Boole, leading to a number of formalisms
proposed for conditional objects, mostly of syntactical, proof-theoretic vein.
  We propose a unifying, semantical approach, in which conditional events are
(projections of) Markov chains, definable in the three-valued extension of the
past tense fragment of propositional linear time logic, or, equivalently, by
three-valued counter-free Moore machines. Thus our conditional objects are
indeed stochastic processes, one of the central notions of modern probability
theory.
  Our model fulfills early ideas of Bruno de Finetti and, moreover, as we show
in a separate paper, all the previously proposed algebras of conditional events
can be isomorphically embedded in our model.


title:
Embedding conditional event algebras into temporal calculus of
  conditionals

abstract:
  In this paper we prove that all the existing conditional event algebras embed
into a three-valued extension of temporal logic of discrete past time, which
the authors of this paper have proposed in anothe paper as a general model of
conditional events.
  First of all, we discuss the descriptive incompleteness of the cea's. In this
direction, we show that some important notions, like independence of
conditional events, cannot be properly addressed in the framework of
conditional event algebras, while they can be precisely formulated and analyzed
in the temporal setting.
  We also demonstrate that the embeddings allow one to use Markov chain
algorithms (suitable for the temporal calculus) for computing probabilities of
complex conditional expressions of the embedded conditional event algebras, and
that these algorithms can outperform those previously known.


title: Two-way Quantum One-counter Automata

abstract:
  After the first treatments of quantum finite state automata by Moore and
Crutchfield and by Kondacs and Watrous, a number of papers study the power of
quantum finite state automata and their variants. This paper introduces a model
of two-way quantum one-counter automata (2Q1CAs), combining the model of
two-way quantum finite state automata (2QFAs) by Kondacs and Watrous and the
model of one-way quantum one-counter automata (1Q1CAs) by Kravtsev. We give the
definition of 2Q1CAs with well-formedness conditions. It is proved that 2Q1CAs
are at least as powerful as classical two-way deterministic one-counter
automata (2D1CAs), that is, every language L recognizable by 2D1CAs is
recognized by 2Q1CAs with no error. It is also shown that several
non-context-free languages including {a^n b^{n^2}} and {a^n b^{2^n}} are
recognizable by 2Q1CAs with bounded error.


title: Electronic Commerce, Consumer Search and Retailing Cost Reduction

abstract:
  This paper explains four things in a unified way. First, how e-commerce can
generate price equilibria where physical shops either compete with virtual
shops for consumers with Internet access, or alternatively, sell only to
consumers with no Internet access. Second, how these price equilibria might
involve price dispersion on-line. Third, why prices may be higher on-line.
Fourth, why established firms can, but need not, be more reluctant than newly
created firm to adopt e-commerce. For this purpose we develop a model where
e-commerce reduces consumers' search costs, involves trade-offs for consumers,
and reduces retailing costs.


title:
Variable and Value Ordering When Solving Balanced Academic Curriculum
  Problems

abstract:
  In this paper we present the use of Constraint Programming for solving
balanced academic curriculum problems. We discuss the important role that
heuristics play when solving a problem using a constraint-based approach. We
also show how constraint solving techniques allow to very efficiently solve
combinatorial optimization problems that are too hard for integer programming
techniques.


title: Analyzing Website Choice Using Clickstream Data

abstract:
  This paper uses clickstream data from Plurimus Corp. (formerly Foveon Corp.)
to analyze user choice of Internet portals. It will show that commonly used
econometric models for examining grocery scanner data can be applied to
clickstream data on advertising-based online markets. Developing a framework to
study consumer choices of free websites is an essential step to better
understanding user behavior on the Internet. The main data for this study is a
clickstream data set consisting of every website visited by 2654 users from
December 27 1999 to March 31 2000. Using this data, I construct several
variables including search success, time spent searching, and whether a website
is an individual's starting page. I also have advertising and media mentions
data. This study helps to increase understanding of user behavior on the
Internet. It explores some key determinants of website choice and simulates
market responses to changes in the online environment. By better understanding
website choice, we can better evaluate the implications of policy decisions.


title:
Algorithmic Self-Assembly of DNA Tiles and its Application to
  Cryptanalysis

abstract:
  The early promises of DNA computing to deliver a massively parallel
architecture well-suited to computationally hard problems have so far been
largely unkept. Indeed, it is probably fair to say that only toy problems have
been addressed experimentally. Recent experimental development on algorithmic
self-assembly using DNA tiles seem to offer the most promising path toward a
potentially useful application of the DNA computing concept. In this paper, we
explore new geometries for algorithmic self-assembly, departing from those
previously described in the literature. This enables us to carry out
mathematical operations like binary multiplication or cyclic convolution
product. We then show how to use the latter operation to implement an attack
against the well-known public-key crypto system NTRU.


title:
Pushdown Timed Automata: a Binary Reachability Characterization and
  Safety Verification

abstract:
  We consider pushdown timed automata (PTAs) that are timed automata (with
dense clocks) augmented with a pushdown stack. A configuration of a PTA
includes a control state, dense clock values and a stack word. By using the
pattern technique, we give a decidable characterization of the binary
reachability (i.e., the set of all pairs of configurations such that one can
reach the other) of a PTA. Since a timed automaton can be treated as a PTA
without the pushdown stack, we can show that the binary reachability of a timed
automaton is definable in the additive theory of reals and integers. The
results can be used to verify a class of properties containing linear relations
over both dense variables and unbounded discrete variables. The properties
previously could not be verified using the classic region technique nor
expressed by timed temporal logics for timed automata and CTL$^*$ for pushdown
systems. The results are also extended to other generalizations of timed
automata.


title: The Minimum Expectation Selection Problem

abstract:
  We define the min-min expectation selection problem (resp. max-min
expectation selection problem) to be that of selecting k out of n given
discrete probability distributions, to minimize (resp. maximize) the
expectation of the minimum value resulting when independent random variables
are drawn from the selected distributions. We assume each distribution has
finitely many atoms. Let d be the number of distinct values in the support of
the distributions. We show that if d is a constant greater than 2, the min-min
expectation problem is NP-complete but admits a fully polynomial time
approximation scheme. For d an arbitrary integer, it is NP-hard to approximate
the min-min expectation problem with any constant approximation factor. The
max-min expectation problem is polynomially solvable for constant d; we leave
open its complexity for variable d. We also show similar results for binary
selection problems in which we must choose one distribution from each of n
pairs of distributions.


title:
Proceedings of the 6th Annual Workshop of the ERCIM Working Group on
  Constraints

abstract:
  Homepage of the workshop proceedings, with links to all individually archived
papers


title: A Proposal for Dynamic Access Lists for TCP/IP Packet Filering

abstract:
  The use of IP filtering to improve system security is well established, and
although limited in what it can achieve has proved to be efficient and
effective.
  In the design of a security policy there is always a trade-off between
usability and security. Restricting access means that legitimate use of the
network is prevented; allowing access means illegitimate use may be allowed.
Static access list make finding a balance particularly stark -- we pay the
price of decreased security 100% of the time even if the benefit of increased
usability is only gained 1% of the time.
  Dynamic access lists would allow the rules to change for short periods of
time, and to allow local changes by non-experts. The network administrator can
set basic security guide-lines which allow certain basic services only. All
other services are restricted, but users are able to request temporary
exceptions in order to allow additional access to the network. These exceptions
are granted depending on the privileges of the user.
  This paper covers the following topics: (1) basic introduction to TCP/IP
filtering; (2) semantics for dynamic access lists and; (3) a proposed protocol
for allowing dynamic access; and (4) a method for representing access lists so
that dynamic update and look-up can be done efficiently performed.


title: The Open Language Archives Community and Asian Language Resources

abstract:
  The Open Language Archives Community (OLAC) is a new project to build a
worldwide system of federated language archives based on the Open Archives
Initiative and the Dublin Core Metadata Initiative. This paper aims to
disseminate the OLAC vision to the language resources community in Asia, and to
show language technologists and linguists how they can document their tools and
data in such a way that others can easily discover them. We describe OLAC and
the OLAC Metadata Set, then discuss two key issues in the Asian context:
language classification and multilingual resource classification.


title: Richer Syntactic Dependencies for Structured Language Modeling

abstract:
  The paper investigates the use of richer syntactic dependencies in the
structured language model (SLM). We present two simple methods of enriching the
dependencies in the syntactic parse trees used for intializing the SLM. We
evaluate the impact of both methods on the perplexity (PPL) and
word-error-rate(WER, N-best rescoring) performance of the SLM. We show that the
new model achieves an improvement in PPL and WER over the baseline results
reported using the SLM on the UPenn Treebank and Wall Street Journal (WSJ)
corpora, respectively.


title: Limits To Certainty in QoS Pricing and Bandwidth

abstract:
  Advanced services require more reliable bandwidth than currently provided by
the Internet Protocol, even with the reliability enhancements provided by TCP.
More reliable bandwidth will be provided through QoS (quality of service), as
currently discussed widely. Yet QoS has some implications beyond providing
ubiquitous access to advance Internet service, which are of interest from a
policy perspective. In particular, what are the implications for price of
Internet services? Further, how will these changes impact demand and universal
service for the Internet. This paper explores the relationship between
certainty of bandwidth and certainty of price for Internet services over a
statistically shared network and finds that these are mutually exclusive goals.


title: The Increased Need For FCC Merger Review In A Networked World

abstract:
  Recently, the FCC announced a new standard for review in mergers. Under the
new standard, mass media mergers that comply with existing rules will
automaticly receive approval, while those that do not will receive a more
searching review. Common carrier mergers, however, will continue to receive the
4=part test established in Bell Atlantic/Nynex. The new standard fails to take
into account the complexities of the emerging, converged networked world, and
is essentially obsolete on arrival. Looking to those areas where Congress has
required an additional public interest review of mergers, a pattern emerges.
The emergence of vast, vertically integrated networks of content and conduit
fit the historic pattern of areas requiring piublic interest review and
re-enforce the need for increased, rather than decreased merger review.


title: ENUM: The Collision of Telephony and DNS Policy

abstract:
  ENUM marks either the convergence or collision of the public telephone
network with the Internet. ENUM is an innovation in the domain name system
(DNS). It starts with numerical domain names that are used to query DNS name
servers. The servers respond with address information found in DNS records.
This can be telephone numbers, email addresses, fax numbers, SIP addresses, or
other information. The concept is to use a single number in order to obtain a
plethora of contact information.
  By convention, the Internet Engineering Task Force (IETF) ENUM Working Group
determined that an ENUM number would be the same numerical string as a
telephone number. In addition, the assignee of an ENUM number would be the
assignee of that telephone number. But ENUM could work with any numerical
string or, in fact, any domain name. The IETF is already working on using E.212
numbers with ENUM. [Abridged]


title: New approach for network monitoring and intrusion detection

abstract:
  The approach for a network behavior description in terms of numerical
time-dependant functions of the protocol parameters is suggested. This provides
a basis for application of methods of mathematical and theoretical physics for
information flow analysis on network and for extraction of patterns of typical
network behavior. The information traffic can be described as a trajectory in
multi-dimensional parameter-time space with dimension about 10-12. Based on
this study some algorithms for the proposed intrusion detection system are
discussed.


title:
Structuring Business Metadata in Data Warehouse Systems for Effective
  Business Support

abstract:
  Large organizations today are being served by different types of data
processing and informations systems, ranging from the operational (OLTP)
systems, data warehouse systems, to data mining and business intelligence
applications. It is important to create an integrated repository of what these
systems contain and do in order to use them collectively and effectively. The
repository contains metadata of source systems, data warehouse, and also the
business metadata. Decision support and business analysis require extensive and
in-depth understanding of business entities, tasks, rules and the environment.
The purpose of business metadata is to provide this understanding. Realizing
the importance of metadata, many standardization efforts has been initiated to
define metadata models. In trying to define an integrated metadata and
information systems for a banking application, we discover some important
limitations or inadequacies of the business metadata proposals. They relate to
providing an integrated and flexible inter-operability and navigation between
metadata and data, and to the important issue of systematically handling
temporal characteristics and evolution of the metadata itself.
  In this paper, we study the issue of structuring business metadata so that it
can provide a context for business management and decision support when
integrated with data warehousing. We define temporal object-oriented business
metadata model, and relate it both to the technical metadata and the data
warehouse. We also define ways of accessing and navigating metadata in
conjunction with data.


title: Alife Model of Evolutionary Emergence of Purposeful Adaptive Behavior

abstract:
  The process of evolutionary emergence of purposeful adaptive behavior is
investigated by means of computer simulations. The model proposed implies that
there is an evolving population of simple agents, which have two natural needs:
energy and reproduction. Any need is characterized quantitatively by a
corresponding motivation. Motivations determine goal-directed behavior of
agents. The model demonstrates that purposeful behavior does emerge in the
simulated evolutionary processes. Emergence of purposefulness is accompanied by
origin of a simple hierarchy in the control system of agents.


title: Mixed-Initiative Interaction = Mixed Computation

abstract:
  We show that partial evaluation can be usefully viewed as a programming model
for realizing mixed-initiative functionality in interactive applications.
Mixed-initiative interaction between two participants is one where the parties
can take turns at any time to change and steer the flow of interaction. We
concentrate on the facet of mixed-initiative referred to as `unsolicited
reporting' and demonstrate how out-of-turn interactions by users can be modeled
by `jumping ahead' to nested dialogs (via partial evaluation). Our approach
permits the view of dialog management systems in terms of their native support
for staging and simplifying interactions; we characterize three different
voice-based interaction technologies using this viewpoint. In particular, we
show that the built-in form interpretation algorithm (FIA) in the VoiceXML
dialog management architecture is actually a (well disguised) combination of an
interpreter and a partial evaluator.


title: Set Unification

abstract:
  The unification problem in algebras capable of describing sets has been
tackled, directly or indirectly, by many researchers and it finds important
applications in various research areas--e.g., deductive databases, theorem
proving, static analysis, rapid software prototyping. The various solutions
proposed are spread across a large literature. In this paper we provide a
uniform presentation of unification of sets, formalizing it at the level of set
theory. We address the problem of deciding existence of solutions at an
abstract level. This provides also the ability to classify different types of
set unification problems. Unification algorithms are uniformly proposed to
solve the unification problem in each of such classes.
  The algorithms presented are partly drawn from the literature--and properly
revisited and analyzed--and partly novel proposals. In particular, we present a
new goal-driven algorithm for general ACI1 unification and a new simpler
algorithm for general (Ab)(Cl) unification.


title: Pretty-Simple Password-Authenticated Key-Exchange Protocol

abstract:
  We propose pretty simple password-authenticated key-exchange protocol which
is based on the difficulty of solving DDH problem. It has the following
advantages: (1) Both $y_1$ and $y_2$ in our protocol are independent and thus
they can be pre-computed and can be sent independently. This speeds up the
protocol. (2) Clients and servers can use almost the same algorithm. This
reduces the implementation costs without accepting replay attacks and abuse of
entities as oracles.


title:
Recognizing When Heuristics Can Approximate Minimum Vertex Covers Is
  Complete for Parallel Access to NP

abstract:
  For both the edge deletion heuristic and the maximum-degree greedy heuristic,
we study the problem of recognizing those graphs for which that heuristic can
approximate the size of a minimum vertex cover within a constant factor of r,
where r is a fixed rational number. Our main results are that these problems
are complete for the class of problems solvable via parallel access to NP. To
achieve these main results, we also show that the restriction of the vertex
cover problem to those graphs for which either of these heuristics can find an
optimal solution remains NP-hard.


title: Information retrieval in Current Research Information Systems

abstract:
  In this paper we describe the requirements for research information systems
and problems which arise in the development of such system. Here is shown which
problems could be solved by using of knowledge markup technologies. Ontology
for Research Information System offered. Architecture for collecting research
data and providing access to it is described.


title: Part-of-Speech Tagging with Two Sequential Transducers

abstract:
  We present a method of constructing and using a cascade consisting of a left-
and a right-sequential finite-state transducer (FST), T1 and T2, for
part-of-speech (POS) disambiguation. Compared to an HMM, this FST cascade has
the advantage of significantly higher processing speed, but at the cost of
slightly lower accuracy. Applications such as Information Retrieval, where the
speed can be more important than accuracy, could benefit from this approach.
  In the process of tagging, we first assign every word a unique ambiguity
class c_i that can be looked up in a lexicon encoded by a sequential FST. Every
c_i is denoted by a single symbol, e.g. [ADJ_NOUN], although it represents a
set of alternative tags that a given word can occur with. The sequence of the
c_i of all words of one sentence is the input to our FST cascade. It is mapped
by T1, from left to right, to a sequence of reduced ambiguity classes r_i.
Every r_i is denoted by a single symbol, although it represents a set of
alternative tags. Intuitively, T1 eliminates the less likely tags from c_i,
thus creating r_i. Finally, T2 maps the sequence of r_i, from right to left, to
a sequence of single POS tags t_i. Intuitively, T2 selects the most likely t_i
from every r_i.
  The probabilities of all t_i, r_i, and c_i are used only at compile time, not
at run time. They do not (directly) occur in the FSTs, but are "implicitly
contained" in their structure.


title: On Equivalence and Canonical Forms in the LF Type Theory

abstract:
  Decidability of definitional equality and conversion of terms into canonical
form play a central role in the meta-theory of a type-theoretic logical
framework. Most studies of definitional equality are based on a confluent,
strongly-normalizing notion of reduction. Coquand has considered a different
approach, directly proving the correctness of a practical equivalance algorithm
based on the shape of terms. Neither approach appears to scale well to richer
languages with unit types or subtyping, and neither directly addresses the
problem of conversion to canonical.
  In this paper we present a new, type-directed equivalence algorithm for the
LF type theory that overcomes the weaknesses of previous approaches. The
algorithm is practical, scales to richer languages, and yields a new notion of
canonical form sufficient for adequate encodings of logical systems. The
algorithm is proved complete by a Kripke-style logical relations argument
similar to that suggested by Coquand. Crucially, both the algorithm itself and
the logical relations rely only on the shapes of types, ignoring dependencies
on terms.


title:
How to Commission, Operate and Maintain a Large Future Accelerator
  Complex from Far Remote

abstract:
  A study on future large accelerators [1] has considered a facility, which is
designed, built and operated by a worldwide collaboration of equal partner
institutions, and which is remote from most of these institutions. The full
range of operation was considered including commi-ssioning, machine
development, maintenance, trouble shooting and repair. Experience from existing
accele-rators confirms that most of these activities are already performed
'remotely'. The large high-energy physics ex-periments and astronomy projects,
already involve inter-national collaborations of distant institutions. Based on
this experience, the prospects for a machine operated remotely from far sites
are encouraging. Experts from each laboratory would remain at their home
institution but continue to participate in the operation of the machine after
construction. Experts are required to be on site only during initial
commissioning and for par-ticularly difficult problems. Repairs require an
on-site non-expert maintenance crew. Most of the interventions can be made
without an expert and many of the rest resolved with remote assistance. There
appears to be no technical obstacle to controlling an accelerator from a
distance. The major challenge is to solve the complex management and
communication problems.


title: Dense point sets have sparse Delaunay triangulations

abstract:
  The spread of a finite set of points is the ratio between the longest and
shortest pairwise distances. We prove that the Delaunay triangulation of any
set of n points in R^3 with spread D has complexity O(D^3). This bound is tight
in the worst case for all D = O(sqrt{n}). In particular, the Delaunay
triangulation of any dense point set has linear complexity. We also generalize
this upper bound to regular triangulations of k-ply systems of balls, unions of
several dense point sets, and uniform samples of smooth surfaces. On the other
hand, for any n and D=O(n), we construct a regular triangulation of complexity
Omega(nD) whose n vertices have spread D.


title:
Depth-3 Arithmetic Circuits for S^2_n(X) and Extensions of the
  Graham-Pollack Theorem

abstract:
  We consider the problem of computing the second elementary symmetric
polynomial S^2_n(X) using depth-three arithmetic circuits of the form "sum of
products of linear forms". We consider this problem over several fields and
determine EXACTLY the number of multiplication gates required. The lower bounds
are proved for inhomogeneous circuits where the linear forms are allowed to
have constants; the upper bounds are proved in the homogeneous model. For reals
and rationals, the number of multiplication gates required is exactly n-1; in
most other cases, it is \ceil{n/2}. This problem is related to the
Graham-Pollack theorem in algebraic graph theory. In particular, our results
answer the following question of Babai and Frankl: what is the minimum number
of complete bipartite graphs required to cover each edge of a complete graph an
odd number of times? We show that for infinitely many n, the answer is
\ceil{n/2}.


title: A logic-based approach to data integration

abstract:
  An important aspect of data integration involves answering queries using
various resources rather than by accessing database relations. The process of
transforming a query from the database relations to the resources is often
referred to as query folding or answering queries using views, where the views
are the resources. We present a uniform approach that includes as special cases
much of the previous work on this subject. Our approach is logic-based using
resolution. We deal with integrity constraints, negation, and recursion also
within this framework.


title: Inference of termination conditions for numerical loops in Prolog

abstract:
  We present a new approach to termination analysis of numerical computations
in logic programs. Traditional approaches fail to analyse them due to non
well-foundedness of the integers. We present a technique that allows overcoming
these difficulties. Our approach is based on transforming a program in a way
that allows integrating and extending techniques originally developed for
analysis of numerical computations in the framework of query-mapping pairs with
the well-known framework of acceptability. Such an integration not only
contributes to the understanding of termination behaviour of numerical
computations, but also allows us to perform a correct analysis of such
computations automatically, by extending previous work on a constraint-based
approach to termination. Finally, we discuss possible extensions of the
technique, including incorporating general term orderings.


title: On termination of meta-programs

abstract:
  The term {\em meta-programming} refers to the ability of writing programs
that have other programs as data and exploit their semantics.
  The aim of this paper is presenting a methodology allowing us to perform a
correct termination analysis for a broad class of practical meta-interpreters,
including negation and performing different tasks during the execution. It is
based on combining the power of general orderings, used in proving termination
of term-rewrite systems and programs, and on the well-known acceptability
condition, used in proving termination of logic programs.
  The methodology establishes a relationship between the ordering needed to
prove termination of the interpreted program and the ordering needed to prove
termination of the meta-interpreter together with this interpreted program. If
such a relationship is established, termination of one of those implies
termination of the other one, i.e., the meta-interpreter preserves termination.
  Among the meta-interpreters that are analysed correctly are a proof trees
constructing meta-interpreter, different kinds of tracers and reasoners.
  To appear without appendix in Theory and Practice of Logic Programming.


title: Efficient algorithms for decision tree cross-validation

abstract:
  Cross-validation is a useful and generally applicable technique often
employed in machine learning, including decision tree induction. An important
disadvantage of straightforward implementation of the technique is its
computational overhead. In this paper we show that, for decision trees, the
computational overhead of cross-validation can be reduced significantly by
integrating the cross-validation with the normal decision tree induction
process. We discuss how existing decision tree algorithms can be adapted to
this aim, and provide an analysis of the speedups these adaptations may yield.
The analysis is supported by experimental results.


title:
Practical Aspects for a Working Compile Time Garbage Collection System
  for Mercury

abstract:
  Compile-time garbage collection (CTGC) is still a very uncommon feature
within compilers. In previous work we have developed a compile-time structure
reuse system for Mercury, a logic programming language. This system indicates
which datastructures can safely be reused at run-time. As preliminary
experiments were promising, we have continued this work and have now a working
and well performing near-to-ship CTGC-system built into the Melbourne Mercury
Compiler (MMC).
  In this paper we present the multiple design decisions leading to this
system, we report the results of using CTGC for a set of benchmarks, including
a real-world program, and finally we discuss further possible improvements.
Benchmarks show substantial memory savings and a noticeable reduction in
execution time.


title: Counting is Easy

abstract:
  For any fixed $k$, a remarkably simple single-tape Turing machine can
simulate $k$ independent counters in real time. Informally, a counter is a
storage unit that maintains a single integer (initially 0), incrementing it,
decrementing it, or reporting its sign (positive, negative, or zero) on
command. Any automaton that responds to each successive command as a counter
would is said to simulate a counter. (Only for a sign inquiry is the response
of interest, of course. And zeroness is the only real issue, since a simulator
can readily use zero detection to keep track of positivity and negativity in
finite-state control. In this paper we describe a remarkably simple real-time
simulation, based on just five simple rewriting rules, of any fixed number $k$
of independent counters. On a Turing machine with a single, binary work tape,
the simulation runs in real time, handling an arbitrary counter command at each
step. The space used by the simulation can be held to $(k+\epsilon) \log_2 n$
bits for the first $n$ commands, for any specified $\epsilon > 0$.


title: Two heads are better than two tapes

abstract:
  We show that a Turing machine with two single-head one-dimensional tapes
cannot recognize the set {x2x'| x \in {0,1}^* and x' is a prefix of x} in real
time, although it can do so with three tapes, two two-dimensional tapes, or one
two-head tape, or in linear time with just one tape. In particular, this
settles the longstanding conjecture that a two-head Turing machine can
recognize more languages in real time if its heads are on the same
one-dimensional tape than if they are on separate one-dimensional tapes.