Jeffrey Ward

• Doctor of Philosophy
• Professor (Associate) at Northern Kentucky University

Chessboard separation problems are modifications to classic chessboard problems, such as the N queens problem, in which obstacles are placed on the chessboard. The N + k queens problem requires placements of k pawns and N + k mutually non-attacking queens on an N -by-N chessboard. Here we examine centrosymmetric (half-turn symmetric) and doubly cen...

Abstract Chessboard separation problems are modiflcations to classic chess- board problems, such as the N Queens Problem, in which obstacles are placed on the chessboard. This paper focuses on a variation known as the N + k Queens Problem, in which k Pawns and N + k mutually non-attacking Queens are to be placed on an N-by-N chess- board. Results a...

A conflict clause represents a backtracking solver's analysis of why a conflict occurred. This analysis can be used to further prune the search space and to direct the search heuristic. The use of such clauses has been very important in improving the efficiency of satisfiability (SAT) solvers over the past few years, especially on structured proble...

We present a new approach to SAT solvers, supporting efficient implementation of highly sophisticated search heuristics over a range of propositional inputs, including CNF formulas, but particularly sets of arbitrary boolean constraints, represented as BDDs. The approach preprocesses the BDDs into state machines to allow for fast inferences based u...