Hisayuki Tatsumi

Game-theoretic approach to placement problems of rectilinear blocks solution of rectilinear jigsaw puzzle

In this paper, a rectilinear jigsaw puzzle is taken up as a specialized placement problem such that it has at least one solution of placement, but not so many in general. In order to solve this problem, instead of adopting the well known iterative method, a new game-theoretic algorithm is developed by translating the problem to a checkmate problem of a game analogous to chess or shogi. It is proved by numerical experiments that this works well with good efficiency.

Logic circuit diagnosis by using neural networks

This paper presents a new method of logic diagnosis for combinatorial logic circuits. First, for each type of circuit gates, an equivalent neural network gate is constructed. Then, by replacing circuit gate elements with corresponding neural network gates, an equivalent neural network circuit is constructed to the fault-free sample circuit. The testing procedure is to feed random patterns to both the neural network circuit and the fault-prone test circuit at the same time, and comparing, analyzing both outputs, the former circuit generates diagnostic data for the test circuit. Thus, the neural network circuit behaves like a diagnostic engine, and needs basically no preparation of special test patterns nor fault dictionary before diagnosing.

Minimization of NAND circuits by rewriting-rules heuristic

A method is given for further minimizing the multilevel NAND gate circuit having single-rail inputs obtained by applying the inhibiting-loop method of K. Goto (1989) to the given function. Using several theorems proposed by the authors several rules are used to determine whether the same input exists in the preceding and succeeding gate levels, and to determine whether the common input exists at the same first level of some parallel multilevel NAND gates, or other conditions. The Lisp language program utilizing this method was run on the microVAX-II computer for three-variable P-equivalence classes and four-variable functions. As a result, the coincidences for the three-variable functions and four-variable functions between the ideal results and the obtained results were 40% and 11%, respectively, when using the inhibiting-loop method alone. However, the results improved to 90% and 64%, respectively, by the addition of this reducing method.<<ETX>>