samplePaper - Using SNARK as a Propositional...

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Using SNARK as a Propositional Knowledge-Based System for CarPool World A Sample Project Report for CSE 4/563 Knowledge Representation Stuart C. Shapiro Department of Computer Science and Engineering 201 Bell Hall University at Buffalo, The State University of New York Buffalo, NY 14260-2000 shapiro@cse.buffalo.edu December 19, 2007 1 Introduction This paper is a report on the use of SNARK (SRI’s New Automated Reasoning Kit) [1, 2] and the query function of the Ask Interface for SNARK [4] as a propositional knowledge-based system for CarPool World [3]. SNARK is a resolution refutation theorem prover that may be given a knowledge base (KB) as a set of assertions, and then may be asked to prove that a well-formed proposition (wfp) is logically implied by that KB. SNARK either produces a refutation proof by deriving the empty clause, or reports that the empty clause cannot be derived. The query function of the Ask Interface assumes that the KB has been loaded, and then is given a comment in the form of a string and a query in the form of a wfp. The query function prints the comment, passes the wfp to the ask function, and prints the answer that ask returns. If SNARK can show that the KB logically implies the query, ask returns True ; if SNARK can show that the KB logically implies the negation of the query, ask returns False ; if neither, ask returns Unknown . In Section 2 of this paper, the CarPool World domain is described. In Section 3, the syntax and semantics of the formalization is presented, along with the formalization of the domain rules and the specific data and questions of the demonstration run. Section 5 contains a transcript of the demonstration run, while the Appendix contains a listing of the file that is used for the demonstration run. 2 The Domain The CarPool World domain is about two people, Tom and Betty, who drive to work together. It is described in [3] as: “Tom and Betty carpool to work. On any day, either Tom drives Betty or Betty drives Tom. In the former case, Tom is the driver and Betty is the passenger. In the latter case, Betty is the driver and Tom is the passenger.” [3, p. 18] 1
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Each day in CarPool World can be characterized completely by which of the following propositions are true, and which are false. Betty drives Tom to work.
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samplePaper - Using SNARK as a Propositional...

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