Abstract

. In this article, we describe a set of procedures and strategies for searching for proofs in logical systems based on the inference rule condensed detachment. The procedures and strategies rely on the derivation of proof sketches|sequences of formulas that are used as hints to guide the search for sound proofs. In the simplest case, a proof sketch consists of a subproof|key lemmas to prove, for example|and the proof is completed by lling in the missing steps. In the more general case, a proof sketch consists of a sequence of formulas sucient to nd a proof, but it may include formulas that are not provable in the current theory. We nd that even in this more general case, proof sketches can provide valuable guidance in nding sound proofs. Proof sketches have been used successfully for numerous problems coming from a variety of problem areas. We have, for example, used proof sketches to nd several new two-axiom systems for Boolean algebra using the Sheer stroke. Keywords: proof sk...

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