A Continuous-Discontinuous Second-Order Transition in the Satisfiability of Random Horn-SAT Formulas

Research paper by Cristopher Moore, Gabriel Istrate, Demetrios Demopoulos, Moshe Y. Vardi

Indexed on: 02 May '05Published on: 02 May '05Published in: Mathematics - Probability


We compute the probability of satisfiability of a class of random Horn-SAT formulae, motivated by a connection with the nonemptiness problem of finite tree automata. In particular, when the maximum clause length is 3, this model displays a curve in its parameter space along which the probability of satisfiability is discontinuous, ending in a second-order phase transition where it becomes continuous. This is the first case in which a phase transition of this type has been rigorously established for a random constraint satisfaction problem.