Paul Walton Purdom

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For a simple parameterized model of conjunctive normal form predicates, we show that a simplified version of the Davis-Putnam procedure can, for many values of the parameters, solve the satisfiability problem in polynomial average time. Let v be the number of variables, t(v) the number of clauses in a predicate, and p(v) the probability that a given literal(More)
Abstract. Backtracking algorithms solve problemsby selecting a variable and assigning each possible value to the variable. The resulting subproblems are simplified and solved recursively. Simple backtracking selects variables in a fixed order. Clause order backtracking selects variables from the first nontrivial clause that has not yet been satisfied.(More)
We assume a directed graph whose nodes are labeled by integers between 1 and <italic>n</italic>. The arcs of this graph correspond to the flow of control between blocks of a computer program. The initial node of this graph (corresponding to the entry point of the program) is labeled by the integer 1. For optimizing the object code generated by a compiler,(More)
An extended LR(k) (ELR(k)) grammar is a context free grammar in which the right sides of the productions are regular expressions and which can be parsed from left to right with k symbol look-ahead. We present a practical algorithm for producing small fast parsers directly from certain ELR(k) grammars, and an algorithm for converting the remaining ELR(k)(More)