07401 Abstracts Collection -- Deduction and Decision Procedures

From 01.10. to 05.10.2007, the Dagstuhl Seminar 07401 ``Deduction and Decision Procedures\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper

Context-Bounded Analysis For Concurrent Programs With Dynamic Creation of Threads

Context-bounded analysis has been shown to be both efficient and effective at finding bugs in concurrent programs. According to its original definition, context-bounded analysis explores all behaviors of a concurrent program up to some fixed number of context switches between threads. This definition is inadequate for programs that create threads dynamically because bounding the number of context switches in a computation also bounds the number of threads involved in the computation. In this paper, we propose a more general definition of context-bounded analysis useful for programs with dynamic thread creation. The idea is to bound the number of context switches for each thread instead of bounding the number of switches of all threads. We consider several variants based on this new definition, and we establish decidability and complexity results for the analysis induced by them

Drug target optimization in chronic myeloid leukemia using innovative computational platform.

Chronic Myeloid Leukemia (CML) represents a paradigm for the wider cancer field. Despite the fact that tyrosine kinase inhibitors have established targeted molecular therapy in CML, patients often face the risk of developing drug resistance, caused by mutations and/or activation of alternative cellular pathways. To optimize drug development, one needs to systematically test all possible combinations of drug targets within the genetic network that regulates the disease. The BioModelAnalyzer (BMA) is a user-friendly computational tool that allows us to do exactly that. We used BMA to build a CML network-model composed of 54 nodes linked by 104 interactions that encapsulates experimental data collected from 160 publications. While previous studies were limited by their focus on a single pathway or cellular process, our executable model allowed us to probe dynamic interactions between multiple pathways and cellular outcomes, suggest new combinatorial therapeutic targets, and highlight previously unexplored sensitivities to Interleukin-3.We would like to thank the members of the Fisher laboratory, in particular to Gavin Smyth and Caroline Dahl for their help with the BMA development, and Alex Hajnal for valuable comments on the manuscript and insightful discussions. Research in BG laboratory is supported by the Medical Research Council, Leukaemia and Lymphoma Research, The Leukemia and Lymphoma Society, Microsoft Research and core support grants by the Wellcome Trust to the Cambridge Institute for Medical Research and Wellcome Trust-MRC Cambridge Stem Cell Institute.This is the final published version. It was originally published in Scientific Reports 5: 8190. DOI: 10.1038/srep08190

Development of a disease-specific health utility score for Chronic Obstructive Pulmonary Disease from a Discrete Choice Experiment patient preference study

Acknowledgements; We wish to acknowledge the support of Katie Mycock, Tom Gardner, Phil Mellor, Pam Hallworth, Kate Sully, Sophi Tatlock, Beyza Klein, Gerard Criner, Pierre-Régis Burgel, Olivier Le Rouzic, Kip Adams, Kirsten Phillips, Mike McKevitt, and Kazuko Toyama for their involvement and contributions to the design, conduct and analysis of this patient preference study, and Kevin Marsh for comments and suggestions for further analyses based on a manuscript draft. Funding statement: The study was funded in full by Novartis Pharma AG. Byron Jones and Nigel Cook are employees of Novartis Pharma AG. At the time of writing, Florian Gutzwiller was an employee of Novartis Pharma AG.Peer reviewe

Partitioning Strategies for Distributed SMT Solving

For many users of Satisfiability Modulo Theories (SMT) solvers, the solver's performance is the main bottleneck in their application. One promising approach for improving performance is to leverage the increasing availability of parallel and cloud computing. However, despite many efforts, the best parallel approach to date consists of running a portfolio of solvers, meaning that performance is still limited by the best possible sequential performance. In this paper, we revisit divide-and-conquer approaches to parallel SMT, in which a challenging problem is partitioned into several subproblems. We introduce several new partitioning strategies and evaluate their performance, both alone as well as within portfolios, on a large set of difficult SMT benchmarks. We show that hybrid portfolios that include our new strategies can significantly outperform traditional portfolios for parallel SMT.Comment: Submitted to FMCAD 202

Symbolic Model Checking for Asynchronous Boolean Programs

Abstract. Software model checking problems generally contain two differ-ent types of non-determinism: 1) non-deterministically chosen values; 2) the choice of interleaving among threads. Most modern software model check-ers can handle only one source of non-determinism efficiently, but not both. This paper describes a SAT-based model checker for asynchronous Boolean programs that handles both sources effectively. We address the first type of non-determinism with a form of symbolic execution and fix-point detection. We address the second source of non-determinism using a symbolic and dy-namic partial-order reduction, which is implemented inside the SAT-solver’s case-splitting algorithm. The preliminary experimental results show that the new algorithm outperforms the existing software model checkers on large benchmarks.

Ranking function synthesis for bit-vector relations

Abstract. Ranking function synthesis is a key aspect to the success of modern termination provers for imperative programs. While it is wellknown how to generate linear ranking functions for relations over (mathematical) integers or rationals, efficient synthesis of ranking functions for machine-level integers (bit-vectors) is an open problem. This is particularly relevant for the verification of low-level code. We propose several novel algorithms to generate ranking functions for relations over machine integers: a complete method based on a reduction to Presburger arithmetic, and a template-matching approach for predefined classes of ranking functions based on reduction to SAT-and QBF-solving. The utility of our algorithms is demonstrated on examples drawn from Windows device drivers