The symmetry rule in propositional logic
The addition of the symmetry rule to the resolution proof system sometimes allows considerable shortening in the length of refutations. An exponential lower bound on the size of resolution refutations using two forms of a global symmetry rule is shown. The paper also discusses the relationship of symmetry rules to the extension rule that allows the use of abbreviative definitions in proofs. Also, symmetry of random clause sets is considered.
exponential lower bound on the size of resolution refutations
scientific article; zbMATH DE number 1389870