정보처리학회논문지A (The KIPS Transactions:PartA)

한국정보처리학회 (Korea Information Processing Society)
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OPKFDD 최소화를 위한 노드의 확장형 결정

Decision of the Node Decomposition Type for the Minimization of OPKFDDs

  • 정미경 (전남대학교 대학원 전산통계학과) ;
  • 황민 (전남대학교 대학원 전산통계학과) ;
  • 이귀상 (전남대학교 정보통신연구소 전산학과) ;
  • 김영철 (전남대학교 전자공학과)
  • 발행 : 2002.09.01
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초록

OPKFDD(Ordered Pseudo-Kronecker Functional Decision Diagram)는 각 노드에서 다양한 확장방법(decomposition)을 취할 수 있는 Ordered-DD(Decision Diagram)의 한 종류로서 각 노드마다 Shannon, positive Davio, 그리고 negative Davio 확장중의 하나를 사용하도록 하며 다른 종류의 DD와 비교해서 작은 수의 노드로 함수를 표현할 수 있다. 그러나 각 노드마다 각기 다른 확장 방법을 선택할 수 있는 특징 때문에 입력 노드에 대한 확장 방법의 결정에 의해서 OPKFDD의 크기가 좌우되며 최소의 노드 수를 갖는 OPKFDD의 구성은 매우 어려운 문제로 알려져 있다. 본 논문에서는 DD 크기의 기준을 노드 수로 하여 기존의 OBDD(Ordered Binary Decision Diagram) 자료구조에서 각 노드의 확장방법을 결정하는 직관적(heuristic)인 방법을 제시하고, 주어진 입력변수 순서에 대해서 각 노드의 확장 방법을 결정하는 알고리즘을 제안하고 실험 결과를 제시한다.

OPKFDD (Ordered Pseudo-Kronecker Functional Decision Diagram) is one of ordered-DDs (Decision Diagrams) in which each node can take one of three decomposition types : Shannon, positive Davio and negative Davio decompositions. Whereas OBDD (Ordered Binary Decision Diagram) uses only the Shannon decomposition in each node, OPKFDD uses the three decompositions and generates representations of functions with smaller number of nodes than other DDs. However, this leads to the extreme difficulty of getting an optimal solution for the minimization of OPKFDD. Since an appropriate decomposition type has to be chosen for each node, the size of the representation is decided by the selection of the decomposition type. We propose a heuristic method to generate OPKFDD efficiently from the OBDD of the given function and the algorithm of the decision of decomposition type for a given variable ordering. Experimental results demonstrate the performance of the algorithm.

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참고문헌

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