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arXiv 1604.00536cs.LOcs.AI
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利用分块子句分解改进SAT求解器

Improving SAT Solvers via Blocked Clause Decomposition

Donghua University(东华大学)

Jingchao Chen

摘要:

最具竞争力的CDCL(基于条件驱动的子句学习)SAT求解器使用的决策变量选择策略是VSIDS(可变状态独立衰减和)或其变体,如指数版本EVSIDS。VSIDS及其变体的共同特点是在求解过程中利用了统计信息,而忽略了问题的结构信息。为此,本文对决策变量选择策略进行了改进,提出了一种基于BCD(Blocked Clause Decomposition)的SAT求解技术。其基本思想是一部分决策变量由VSIDS启发式算法选择,另一部分决策变量由BCD算法得到的分块集选择。与现有的基于BCD码的方法相比,该方法简单,不需要对CNF公式进行重新编码。经过认证的UNSAT轨道的SAT解算器也可以应用我们基于BCD的技术。我们的应用程序基准测试的实验表明,新的变量选择策略的基础上BCD可以提高SAT求解器,如abcdSAT的性能。带有BCD的求解器解决了SAT Race 2015中的一个实例,该实例迄今为止尚未被任何求解器解决。这表明在某些情况下,基于结构信息的启发式算法比基于统计信息的启发式算法更有效。

英文摘要:

The decision variable selection policy used by the most competitive CDCL (Conflict-Driven Clause Learning) SAT solvers is either VSIDS (Variable State Independent Decaying Sum) or its variants such as exponential version EVSIDS. The common characteristic of VSIDS and its variants is to make use of statistical information in the solving process, but ignore structure information of the problem. For this reason, this paper modifies the decision variable selection policy, and presents a SAT solving technique based on BCD (Blocked Clause Decomposition). Its basic idea is that a part of decision variables are selected by VSIDS heuristic, while another part of decision variables are selected by blocked sets that are obtained by BCD. Compared with the existing BCD-based technique, our technique is simple, and need not to reencode CNF formulas. SAT solvers for certified UNSAT track can apply also our BCD-based technique. Our experiments on application benchmarks demonstrate that the new variables selection policy based on BCD can increase the performance of SAT solvers such as abcdSAT. The solver with BCD solved an instance from the SAT Race 2015 that was not solved by any solver so far. This shows that in some cases, the heuristic based on structure information is more efficient than that based on statistical information.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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