Dead Problem of Program Nets

Shingo YAMAGUCHI  Kousuke YAMADA  Qi-Wei GE  Minoru TANAKA  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E89-A   No.4   pp.887-894
Publication Date: 2006/04/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e89-a.4.887
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Selected Papers from the 18th Workshop on Circuits and Systems in Karuizawa)
program nets,  dead,  dead problem,  computation complexity,  NP-completeness,  

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In this paper, we discuss a new property, named dead, of (dataflow) program nets. We say that a node of a program net is dead iff the node cannot fire once in any possible firing sequence, and furthermore the program net is partially dead. We tackle a problem of deciding whether a given program net is partially dead, named dead problem. Program nets can be classified into four subclasses: general, acyclic, SWITCH-less, and acyclic SWITCH-less nets. For each subclass, we give a method of solving dead problem and its computation complexity. Our results show that (i) acyclic SWITCH-less nets are not partially dead; (ii) for SWITCH-less nets, dead problem can be solved in polynomial time; (iii) for acyclic nets and general nets, dead problem is intractable.