Composition of Reduced Ordered Binary Decision Diagrams
نویسنده
چکیده
A widely accepted opinion is that, under a certain ordering restriction, the class of Reduced Ordered Binary Decision Diagrams (ROBDDs) is closed under composition. However, in this paper we show that this is not correct. We formulate necessary and sufficient conditions for the composition of two ROBDDs to result in a non-reduced OBDD. Ignoring these conditions may lead to an incorrect conclusion about the canonicity of the composed graph or to an inaccurate estimation of its size. We also prove that, on the other hand, under a certain ordering restriction, the class of ROBDDs with complemented edges is indeed closed under composition.
منابع مشابه
A Comment on 'Graph-Based Algorithm for Boolean Function Manipulation'
ÐIn this paper, a slight error in the paper of Bryant [1] is corrected. It was stated in [1] that, under a certain ordering restriction, composition of two Reduced Ordered Binary Decision Diagrams (ROBDDs) results in a reduced OBDD. We show a counterexample and explore under which conditions this statement is incorrect. Index TermsÐBoolean function, Binary Decision Diagram, composition.
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