arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.13601cs.LO
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整数上非线性公式的不完全SMT技巧

Incomplete SMT Techniques for Solving Non-Linear Formulas over the Integers

Cristina Borralleras, Daniel Larraz, Albert Oliveras, Enric Rodriguez-Carbonell, Albert Rubio

摘要:

本文提出了一种新的方法来解决可满足性模理论问题,该方法是在无量词非线性代数算法SMT(QF-NIA)理论的基础上,对整数多项式约束下的基公式的可满足性进行判定.根据以前的工作,我们建议解决SMT(QF-NIA)的情况下,通过减少他们的线性算术:非线性单项式线性化,通过抽象他们与新鲜的变量和执行情况分裂的整数变量与有限域。对于没有有限域的变量,我们可以人为地通过施加一个下限和一个上限来引入一个,并迭代地扩大它,直到找到一个解(或过程超时)。该方法成功的关键是在每次迭代中确定哪些域必须扩展。以前,不可满足的核心被用来识别要改变的域,但没有得到关于新域应该有多大的线索。在这里,我们解释了两种新的方法来指导这个过程,通过分析优化问题的解决方案:(i)最大限度地减少违反人工域边界的数量,通过Max-SMT求解器解决,以及(ii)最小化相对于人工域的距离,通过优化模理论(OMT)求解器解决。使用这种基于SMT的优化技术允许平滑地扩展该方法,也可以通过非线性整数运算来解决Max-SMT问题。最后,我们利用得到的最大SMT(QF-NIA)技术来解决$\exists \forall$公式的量化的非线性算术的一个片段,通常出现在验证和合成应用。

英文摘要:

We present new methods for solving the Satisfiability Modulo Theories problem over the theory of Quantifier-Free Non-linear Integer Arithmetic, SMT(QF-NIA), which consists in deciding the satisfiability of ground formulas with integer polynomial constraints. Following previous work, we propose to solve SMT(QF-NIA) instances by reducing them to linear arithmetic: non-linear monomials are linearized by abstracting them with fresh variables and by performing case splitting on integer variables with finite domain. For variables that do not have a finite domain, we can artificially introduce one by imposing a lower and an upper bound, and iteratively enlarge it until a solution is found (or the procedure times out). The key for the success of the approach is to determine, at each iteration, which domains have to be enlarged. Previously, unsatisfiable cores were used to identify the domains to be changed, but no clue was obtained as to how large the new domains should be. Here we explain two novel ways to guide this process by analyzing solutions to optimization problems: (i) to minimize the number of violated artificial domain bounds, solved via a Max-SMT solver, and (ii) to minimize the distance with respect to the artificial domains, solved via an Optimization Modulo Theories (OMT) solver. Using this SMT-based optimization technology allows smoothly extending the method to also solve Max-SMT problems over non-linear integer arithmetic. Finally we leverage the resulting Max-SMT(QF-NIA) techniques to solve $\exists \forall$ formulas in a fragment of quantified non-linear arithmetic that appears commonly in verification and synthesis applications.

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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