Niklas Sörensson

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We present a simple but novel algorithm for checking liveness properties of finite-state systems, called k-LIVENESS, which is based on counting and bounding the number of times a fairness constraint can become true. Our implementation of the algorithm is completely SAT-based, works fairly well in practice, and is competitive in performance with alternative(More)
Minimizing learned clauses is an effective technique to reduce memory usage and also speed up solving time. It has been implemented in MINISAT since 2005 and is now adopted by most modern SAT solvers in academia, even though it has not been described in the literature properly yet. With this paper we intend to close this gap and also provide a thorough(More)
SAT solvers are often challenged with very hard problems that remain unsolved after hours of CPU time. The research community meets the challenge in two ways: (1) by improving the SAT solver technology, for example, perfecting heuristics for variable ordering, and (2) by inventing new ways of constructing simpler SAT problems, either using domain specific(More)
Satisfiability solving, the problem of deciding whether the variables of a propositional formula can be assigned in such a way that the formula evaluates to true, is one of the classic problems in computer science. It is of theoretical interest because it is the canonical NP-complete problem. It is of practical interest because modern SAT-solvers can be(More)
The BDDand SAT-based model checking and verification methods normally require an initial state. Here we are concerned with sequential hardware verification, where an initial state must be one of the reset states. In practice, a reset state is not always given by the designer, and computing a reset state of a circuit is a hard problem. In this paper we(More)
Constraint merging tableaux maintain a system of all closing substitutions of all subtableau up to a certain depth, which is incrementally increased. This avoids backtracking as necessary in destructive first order free variable tableaux. The first successful implementation of this paradigm was given in an object-oriented style. We analyse the reasons why(More)