Abstract
Solving a quantified constraint satisfaction problem (QCSP) is usually a hard task due to its computational complexity. Exact algorithms play an important role in solving this problem, among which backtrack algorithms are effective. In a backtrack algorithm, an important step is assigning a variable by a chosen value when exploiting a branch, and thus a good value selection rule may speed up greatly. In this paper, we propose two value selection rules for existentially and universally quantified variables, respectively, to avoid unnecessary searching. The rule for universally quantified variables is prior to trying failure values in previous branches, and the rule for existentially quantified variables selects the promising values first. Two rules are integrated into the state-of-the-art QCSP solver, i.e., QCSP-Solve, which is an exact solver based on backtracking. We perform a number of experiments to evaluate improvements brought by our rules. From computational results, we can conclude that the new value selection rules speed up the solver by 5 times on average and 30 times at most. We also show both rules perform well particularly on instances with existentially and universally quantified variables occurring alternatively.
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Acknowledgements
We would like to thank Dr. Peter Nightingale for the source code of QCSP-Solve. The work described in this paper was supported by the National Natural Science Foundation of China (Granted Nos. 61972063, 61763003, 61672122, 61602077, 61402070), and the Fundamental Research Funds for the Central Universities (3132019029, 3132019355).
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Jian Gao received the PhD degree in Computer Application Technology from Dalian Maritime University, China. He is currently an associate professor of software engineering in Dalian Maritime University, China. His research interests include constraint programming and automatic reasoning.
Jinyan Wang received the MS and PhD degrees in Computer Application Technology and Operational Research and Cybernetics from Northeast Normal University, China, respectively. She is currently an associate professor of College of Computer Science and Information Technology in Guangxi Normal University, China. Her research interests include data security, uncertainty theory, and automatic reasoning.
Kuixian Wu is currently pursuing the MS degree in Computer Science and Technology from Dalian Maritime University, China. His research interest is combinatorial optimization.
Rong Chen received the MS and PhD degrees in Computer Software and Theory from Jilin University, China in 1997 and 2000. He is currently a professor of Dalian Maritime University, and has previously held position at Sun Yat-sen University, China. His research interests are in software diagnosis, collective intelligence, activity recognition, Internet and mobile computing.
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Gao, J., Wang, J., Wu, K. et al. Solving quantified constraint satisfaction problems with value selection rules. Front. Comput. Sci. 14, 145317 (2020). https://doi.org/10.1007/s11704-019-9179-9
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DOI: https://doi.org/10.1007/s11704-019-9179-9