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Abduction is inference to the best explanation. In the TACITUS project at SRI we have developed an approach to abductive inference, called "weighted abduction", that has resulted in a significant simplification of how the problem of interpreting texts is conceptualized. The interpretation of a text is the minimal explanation of why the text would be true.(More)
Theory resolution constitutes a set of complete procedures for incorporating theories into a resolution theorem-proving program, thereby making it unnecessary to resolve directly upon axioms of the theory. This can greatly reduce the length of proofs and the size of the search space. Theory resolution eeects a beneecial division of labor, improving the(More)
FASTUS is a system for extracting information from natural language text for entry into a database and for other applications. It works essentially as a cascaded, nondeterministic nite-state automaton. There are ve stages in the operation of FASTUS. In Stage 1, names and other xed form expressions are recognized. In Stage 2, basic noun groups, verb groups,(More)
An extenston of the Knuth-Bendix algorithm for finding complete sets of reductions is described. The extension is intended to handle equational theories which can be split into two parts, R and T, such that each equation m R can be construed as a reduction and T represents an equational theory for which a finite, complete umficat~on algorithm ~s known. The(More)
Automated deduction techniques are being used in a system called Amphion to derive, from graphical speciications, programs composed from a subroutine library. The system has been applied to construct software for the planning and analysis of interplanetary missions. The library for that application is a collection of subroutines written in FORTRAN-77 at JPL(More)
A Prolog technology theorem prover (PTTP) is an extension of Prolog that is complete for the full rst-order predicate calculus. It diiers from Prolog in its use of uniication with the occurs check for soundness, the model-elimination reduction rule that is added to Prolog inferences to make the inference system complete, and depth-rst iterative-deepening(More)
The method proposed by Davis, Putnam, Logemann, and Loveland for propositional reasoning, often referred to as the Davis–Putnam method, is one of the major practical methods for the satisfiability (SAT) problem of propositional logic. We show how to implement the Davis–Putnam method efficiently using the trie data structure for propositional clauses. A new(More)
New methods to generate hard random problem instances have driven progress on algorithms for deduction and constraint satisfaction. Recently Achlioptas et al. (AAAI 2000) introduced a new generator based on Latin squares that creates only satisfiable problems, and so can be used to accurately test incomplete (one sided) solvers. We investigate how this and(More)