Incremental Satisfiability Solving and its Applications

Aalto University, P.O. Box 11000, FI-00076 Aalto www.aalto.fi Author Siert Wieringa Name of the doctoral dissertation Incremental Satisfiability Solving and its Applications Publisher School of Science Unit Department of Computer Science and Engineering Series Aalto University publication series DOCTORAL DISSERTATIONS 20/2014 Field of research Computer Science and Engineering Manuscript submitted 1 November 2013 Date of the defence 14 March 2014 Permission to publish granted (date) 17 January 2014 Language English Monograph Article dissertation (summary + original articles) Abstract The propositional logic satisfiability problem (SAT) is a computationally hard decision problem. Despite its theoretical hardness, decision procedures for solving instances of this problem have become surprisingly efficient in recent years. These procedures, known as SAT solvers, are able to solve large instances originating from real-life problem domains, such as artificial intelligence and formal verification. Such real-life applications often require solving several related instances of SAT. Therefore, modern solvers posses an incremental interface that allows the input of sequences of incrementally encoded instances of SAT. When solving these instances sequentially the solver can reuse some of the information it has gathered across related consecutive instances.The propositional logic satisfiability problem (SAT) is a computationally hard decision problem. Despite its theoretical hardness, decision procedures for solving instances of this problem have become surprisingly efficient in recent years. These procedures, known as SAT solvers, are able to solve large instances originating from real-life problem domains, such as artificial intelligence and formal verification. Such real-life applications often require solving several related instances of SAT. Therefore, modern solvers posses an incremental interface that allows the input of sequences of incrementally encoded instances of SAT. When solving these instances sequentially the solver can reuse some of the information it has gathered across related consecutive instances. This dissertation contains six publications. The two focus areas of the combined work are incremental usage of SAT solvers, and the usage of parallelism in applications of SAT solvers. It is shown in this work that these two seemingly contradictory concepts form a natural combination. Moreover, this dissertations unifies, analyzes, and extends the results of the six publications, for example, by studying information propagation in incremental solvers through graphical visualizations. The concrete contributions made by the work in this dissertation include, but are not limited to: Improvements to algorithms for MUS finding, the use of graphical visualizations to understand information propagation in incremental solvers, asynchronous incremental solving, and concurrent clause strengthening.