Structural rule A famous structural rule is known as cut. Considerable effort is spent by proof theorists in showing that cut rules are superfluous in various logics. More precisely, what is shown is that cut is only (in a sense) a tool for abbreviating proofs, and does not add to the theorems that can be proved. The successful 'removal' of cut rules, known as "cut elimination", is directly related to the philosophy of "computation as normalization" (see Curry–Howard correspondence); it often gives a good indication of the complexity of deciding a given logic. Structural rule In proof theory, a structural rule is
Uptick rule on 2009-04-08. A modified form of the rule was adopted on 2010-02-24. In 1938, the U.S. Securities and Exchange Commission (SEC) adopted the uptick rule, more formally known as "rule 10a-1", after conducting an inquiry into the effects of concentrated short selling during the market break of 1937. The original rule was implemented when Joseph P. Kennedy, Sr. was SEC commissioner. In 1994, the NASD and Nasdaq adopted their own short sale price tests, known as NASD Rule 3350, based on the last bid rather than on the last reported sale. In 1978, the purpose of the uptick rule was