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Detecting State Coding Conflicts in STG Unfoldings Using SAT

Lookup NU author(s): Dr Victor Khomenko, Professor Maciej KoutnyORCiD, Professor Alex Yakovlev


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The behaviour of asynchronous circuits is often described by Signal Transition Graphs (STGs), which are Petri nets whose transitions are interpreted as rising and falling edges of signals. One of the crucial problems in the synthesis of such circuits is that of identifying whether an STG satisfies the Complete State Coding (CSC), Unique State Coding (USC), or normalcy (a necessary condition for their implementability using gates without input invertors) requirements, e.g. by using model checking based on the reachability graph of an STG. In this paper, we avoid constructing the reachability graph of an STG, which can lead to state space explosion, and instead use only the information about causality and structural conflicts between the events involved in a finite and complete prefix of its unfolding. The model checking algorithm is derived by adopting the Boolean Satisfiability (SAT) approach. Following the basic formulation of the state coding conflict relationship, we present some problem-specific optimization rules. This technique leads not only to huge memory savings when compared to the CSC/USC/normalcy violation detection methods based on reachability graphs, but also to significant speedups in many cases.

Publication metadata

Author(s): Khomenko V, Koutny M, Yakovlev A

Publication type: Report

Publication status: Published

Series Title: Department of Computing Science Technical Report Series

Year: 2002

Pages: 20

Print publication date: 01/09/2002

Source Publication Date: September 2002

Report Number: 778

Institution: Department of Computing Science, University of Newcastle upon Tyne

Place Published: Newcastle upon Tyne