Counting the number of solutions for instances of satisfiability
Theoretical Computer Science
Information Processing Letters
On the hardness of approximate reasoning
Artificial Intelligence
The Complexity of Counting in Sparse, Regular, and Planar Graphs
SIAM Journal on Computing
Counting models for 2SAT and 3SAT formulae
Theoretical Computer Science
A tighter bound for counting max-weight solutions to 2SAT instances
IWPEC'08 Proceedings of the 3rd international conference on Parameterized and exact computation
A Threshold for a Polynomial Solution of #2SAT
Fundamenta Informaticae - Latin American Workshop on Logic Languages, Algorithms and New Methods of Reasoning (LANMR)
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We present some results about the parametric complexity of #2SAT and #2UNSAT, which consist on counting the number of models and falsifying assignments, respectively, for two Conjunctive Forms (2-CF's) . Firstly, we show some cases where given a formula F, #2SAT(F) can be bounded above by considering a binary pattern analysis over its set of clauses. Secondly, since #2SAT(F)=2n-#2UNSAT(F) we show that, by considering the constrained graph GF of F, if GF represents an acyclic graph then, #UNSAT(F) can be computed in polynomial time. To the best of our knowledge, this is the first time where #2UNSAT is computed through its constrained graph, since the inclusion-exclusion formula has been commonly used for computing #UNSAT(F).