Phase transitions of PP-complete satisfiability problems
The complexity class PP consists of all decision problems solvable by polynomial-time probabilistic Turing machines. It is well known that PP is a highly intractable complexity class and that PP-complete problems are in all likelihood harder than NP-complete problems. We investigate the existence of...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2007 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:10230/36324 |
| Acceso en línea: | http://hdl.handle.net/10230/36324 http://dx.doi.org/10.1016/j.dam.2006.09.014 |
| Access Level: | acceso abierto |
| Palabra clave: | Phase transitions Satisfiability PP-complete |
| Sumario: | The complexity class PP consists of all decision problems solvable by polynomial-time probabilistic Turing machines. It is well known that PP is a highly intractable complexity class and that PP-complete problems are in all likelihood harder than NP-complete problems. We investigate the existence of phase transitions for a family of PP-complete Boolean satisfiability problems under the fixed clauses-to-variables ratio model. A typical member of this family is the decision problem # 3SAT: given a 3CNF-formula, is it satisfied by at least the square-root of the total number of possible truth assignments? We provide evidence to the effect that there is a critical ratio at which the asymptotic probability of # 3SAT undergoes a phase transition from 1 to 0. We obtain upper and lower bounds for by showing that . We also carry out a set of experiments on random instances of # 3SAT using a natural modification of the Davis–Putnam–Logemann–Loveland (DPLL) procedure. Our experimental results suggest that . Moreover, the average number of recursive calls of this modified DPLL procedure reaches a peak around 2.5 as well. |
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