Observed Lower Bounds for Random 3-SAT Phase Transition Density Using Linear Programming

Marijn Heule

(TU Delft)

We introduce two incomplete polynomial time algorithms to solve satisfiability problems which both use Linear Programming (LP) techniques. First, the FlipFlop LP attempts to simulate a Quadratic Program which would solve the CNF at hand. Second, the Weighted Linear Autarky LP is an extended variant of the Linear Autarky LP as defined by Kullmann and iteratively updates its weights to find autarkies in a given formula. Besides solving satisfiability problems, this LP could also be used to study the existence of autark assignments in formulas. Results within the experimental domain (up to 1000 variables) show a considerably sharper lower bound for the uniform random 3-Sat phase transition density than the proved lower bound of the myopic algorithm (> 3.26) by Achlioptas and even than that of the greedy algorithm (> 3.52) proposed by Kaporis.
Thursday 7th July 2005, 14:00
Robert Recorde Room
Department of Computer Science