


From: patrick hayes <phayes@ai.uwf.edu>
Date: Wed, 12 Jun 2002 16:55:18 -0500
Message-Id: <p05111a10b92d5cc6d2b3@[]>
To: "Jonathan Borden" <jonathan@openhealth.org>, Jim Hendler <hendler@cs.umd.edu>
Cc: www-rdf-logic@w3.org

>Peter Crowther wrote:
>>... I believe humans can, with sufficient
>>  effort, make *some* stuff work well enough to trust without having the
>>  formal semantics.  In particular, the following aspects make it easy:
>>  1) Bilateral communications rather than peer-to-peer, allowing effective
>>  communication between producer and consumer of specification;
>>  common understanding to start with;
>>  3) Restricted problem domains, such as a credit card application, giving a
>>  limited scope for any such communication;
>>  4) Past experience of similar problems, giving a history of known
>>  5) Shared language between producer and consumer of specification;
>Certainly this is important. But what about "shared language" on the
>semantic web ... how does one really define what the semantics of a given
>URI is, in a formal sense.

Easy. A URI is an individual name. In any interpretation, it refers 
to an entity in the universe of the interpretation.

There may be more to say, of course, but this much enables us to at 
least get started.

>It seems that unless this is done in an
>unambiguous fashion, any formal infrastructure built on top is sort of like
>rearranging, err straightening, deck chairs ...

than each deck chair having its own compass.

>>  6) Limited scope of implementation, for example a single banking system
>>  communicating with a central card issuer system;
>>  7) Limited variation of environment, for example a credit card system that
>>  deploys particular card swipe hardware and software.
>>  All of these simplifying factors were present in your example.  None of
>>  these simplifying factors are present on the semantic web.  I consider the
>>  comparison between the two cases to be specious for that reason.
>I wonder if the semantic web can meaningfully work without some of these
>assumptions. An actual example of a working semantic web application that
>doesn't make some of these would be helpful in convincing me otherwise.

I think everyone agrees that we will need to rely on such assumptions 
for the forseeable future.

the SW content exchange languages having a clear semantics is somehow 
taking a stance against the existence of social conventions. (This 
weird idea seems to arise from some equally weird flaw in Jim 
Hendler's education.) The point is, rather, how to have some 
confidence that these social conventions are preserved when the 
people aren't in the room, when innumerable pieces of software are 
exchanging information with each other on a large variety of topics, 
drawing conclusions (using techniques, and other information, unknown 
to the people who wrote the original content) and then passing those 
conclusions on to other pieces of software, all this happening so 
rapidly and on such a scale that it is completely impossible for 
human beings to check it all. (And of COURSE the code was *written* 
by people. Sigh.) That is the problem that requires us, as designers 
of the protocols that these pieces of software will use, to make 
every effort to ensure that the meanings that are finally produced, 
or the actions that are finally taken, do in fact still conform to 
the social conventions used by the people who originally composed the 
content and who write the code which is manipulating it; and that 
this is true no matter how long the chain of inferences, or how 
varied the processes and processors that produced them, as long as 
they all conform to the specs we write. This isn't easy to do in any 
large network of systems. The SW, if it ever exists, will be a system 
on a scale hitherto unimaginable.

I'm not asking for cast-iron guarantees that it will all work 
properly (still less for machine-checkable proofs that it will, which 
is why Jim's reference to Millo et al is completely beside the point 
here) and of course Im not arguing that things like 404 errors will 
never happen, or that the world is not a scruffy, untidy, place. I 
know it is; that is the point. And for the record, I never, ever, use 
the phrase 'pure logic'.


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Received on Wednesday, 12 June 2002 17:55:21 GMT
