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
Chatham House Rule so that better international relations may be achieved. The rule is now used internationally as an aid to free discussion. The original rule of 1927 was refined in October 1992 and again in 2002. Chatham House has translated the rule into Arabic, Chinese, French, German, Portuguese, Spanish and Russian. The rule is a contrast (or a compromise) between private meetings, where revealing what was said in the meeting is forbidden, and "on the record" events where the discussion is completely public and attributed. Generally, the Chatham House Rule is imposed as a condition of being allowed to attend a meeting