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Mathematical Problems in Engineering
Volume 2017, Article ID 1567378, 8 pages
Research Article

Time-Free Solution to SAT Problem by Tissue P Systems

1College of Computer Science, Chongqing University, Chongqing 400030, China
2College of Computer Engineering, Yangtze Normal University, Chongqing 408100, China

Correspondence should be addressed to Yueguo Luo; nc.ude.uqc@oulgy

Received 15 December 2016; Revised 15 January 2017; Accepted 19 January 2017; Published 23 February 2017

Academic Editor: Nicolas Hudon

Copyright © 2017 Yueguo Luo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Tissue P systems are a class of computing models inspired by intercellular communication, where the rules are used in the nondeterministic maximally parallel manner. As we know, the execution time of each rule is the same in the system. However, the execution time of biochemical reactions is hard to control from a biochemical point of view. In this work, we construct a uniform and efficient solution to the problem with tissue P systems in a time-free way for the first time. With the P systems constructed from the sizes of instances, the execution time of the rules has no influence on the computation results. As a result, we prove that such system is shown to be highly effective for NP-complete problem even in a time-free manner with communication rules of length at most 3.