一句话:证明 Maslov 类 K 具有指数模型性质,从而确定其可满足性问题是 NExpTime 完全的。
Maslov 类 K 是一阶逻辑中一个表达力较强的片段,其可满足性问题已知可判定,但精确复杂度长期未确定。本文证明 K 具有指数规模模型性质,即若公式可满足则存在指数大小模型,由此得到其可满足性问题是 NExpTime 完全的。方法上,作者使用为 K 定制的可满足性博弈,并新颖地将悖论性锦标赛图应用于复杂度分析。除主结果外,论文还给出文献中若干相关片段的新复杂度结果,并提出无等词的一致一维片段的一个新的可判定扩展。这些结果厘清了一阶逻辑可判定片段的复杂度版图,并展示了博弈与组合图论工具在其中的作用。
Maslov's class K is an expressive fragment of First-Order Logic known to have decidable satisfiability problem, whose exact complexity, however, has not been established so far. We show that K has the exponential-sized model property, and hence its satisfiability problem is NExpTime-complete. Additionally, we get new complexity results on related fragments studied in the literature, and propose a new decidable extension of the uniform one-dimensional fragment (without equality). Our approach involves a use of satisfiability games tailored to K and a novel application of paradoxical tournament graphs.