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
No-impeachment rule No-impeachment rule The no-impeachment rule (also known as the non-impeachment rule) is a rule in the procedural law of many jurisdictions. It says testimony from jurors about what occurred during jury deliberations may not be used to impeach a verdict during an appeal. The rule originated in common law and has been codified into statute in many jurisdictions. The United States Federal Rules of Evidence, section 606(b) defines it as: (1) Prohibited Testimony or Other Evidence. During an inquiry into the validity of a verdict or indictment, a juror may not testify about any statement made or incident that occurred