A Model of Random Industrial SAT
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One of the most studied models of SAT is random SAT. In this model, instances are composed from clauses chosen uniformly randomly and independently of each other. This model may be unsatisfactory in that it fails to describe various features of SAT instances, arising in real-world applications. Various modifications have been suggested to define models of industrial SAT. Here, we focus on community-structured SAT. Namely, the set of variables consists of a number of disjoint communities, and clauses tend to consist of variables from the same community. Thus, we suggest a model of random community-structured SAT. There has been a lot of work on the satisfiability threshold of random k-SAT, starting with the calculation of the threshold of 2-SAT, up to the recent result that the threshold exists for sufficiently large k. In this paper, we endeavor to study the satisfiability threshold for random industrial SAT. Our main result is that the threshold of random community-structured SAT tends to be smaller than its counterpart for random SAT. Moreover, under some conditions, this threshold even vanishes.
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