Resolution theorem proving provides a useful paradigm for the exploration of question answering. A partition of the clauses generated during resolution refutation based on their syntactic structure is presented. The three classes comprising this partition correspond to semantically intuitive types of answers. This work encompasses and expands upon previous work on question answering in a theore...

A paper published in 1925 reported that human fetuses with anencephaly have arms that are longer than normal. This finding was accepted as true through the early 1990s. An analysis of body dimensions done in 1996 and enlarged and updated here shows that the arms of human fetuses with anencephaly are appropriate for gestational age and normal in proportion to their leg lengths. A subtle differen...

The Maryland Refutation Proof Procedure Systems (MRPPS) is an interactil perimental system intended for studying deductive search methods. Although the work is oriented towards question answering, MRPPS provides a general problem solving capability. There are three major components within MRPPS. These are: (1) an inference system, (2) a search strategy, and S (3) a base clause selection strateg...

We develop a proof technique for dealing with narrowing and refutational theorem proving in a uniform way, clarifying the exact relationship between the existing results in both elds and allowing us to obtain several new results. Reenements of narrowing (basic, LSE, etc.) are instances of the technique, but are also deened here for arbitrary (possibly ordering and/or equality constrained or not...

Aslam presents an algorithm he claims will count the number of perfect matchings in any incomplete bipartite graph with an algorithm in the function-computing version of NC, which is itself a subset of FP. Counting perfect matchings is known to be #P-complete; therefore if Aslam's algorithm is correct, then NP=P. However, we show that Aslam's algorithm does not correctly count the number of per...

We report initial results on shortening propositional resolution refutation proofs. This has an application in speeding up deductive reconstruction (in theorem provers) of large propositional refutations, such as those produced by SAT-solvers.

This paper develops and compares two tableaux-style proof systems for Peirce algebras. One is a tableau refutation proof system, the other is a proof system in the style of Rasiowa-Sikorski.

In this note we provide a short and elementary proof for the well known fact that first order resulution extended with paramodulation is a sound and refutation complete calculus.