Symmetry in gardens of Eden

Conway's Game of Life has inspired enthusiasts to search for a wide range of patterns for this classic cellular automaton. One important challenge in this context is finding the smallest Garden of Eden (GoE), a state without a predecessor. We take up this challenge by applying two techniques. First, we focus on GoEs that contain a symmetry. This...

Reusing the Assignment Trail in CDCL Solvers: System description

We present the solver RestartSAT which includes a novel technique to reduce the cost to perform a restart in CDCL SAT solvers. This technique, called ReusedTrail, exploits the observation that CDCL solvers often reassign the same variables to the same truth values after a restart. It computes a partial restart level for which it is guaranteed...

Whose side are you on?: Finding solutions in a biased search-tree

We introduce a new jump strategy for look-ahead based satisfiability (Sat) solvers that aims to boost their performance on satisfiable formulae, while maintaining their behavior on unsatisfiable instances. Direction heuristics select which Boolean value to assign to a decision variable. They are used in various state-of-the-art Sat solvers and...

Parallel SAT Solving using Bit-level Operations

We show how to exploit the 32/64 bit architecture of modern computers to accelerate some of the algorithms used in satisfiability solving by modifying assignments to variables in parallel on a single processor. Techniques such as random sampling demonstrate that while using bit vectors instead of Boolean values solutions to satisfiable formulae...

March dl: Adding Adaptive Heuristics and a New Branching Strategy

We introduce the march dl satisability (SAT) solver, a successor of march eq. The latter was awarded state-of-the-art in two categories during the Sat 2004 competition. The focus lies on presenting those features that are new in march dl. Besides a description, each of these features is illustrated with some experimental results. By extending...