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arXiv 1206.3902cs.LOcs.AIcs.CC
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论势正函数的复杂性

On the Complexity of Existential Positive Queries

Universitat Pompeu Fabra(庞培法布拉大学)

Hubie Chen

摘要:

系统地研究了一阶逻辑存在性正片段的模型检验的复杂性。特别是,对于一组存在的肯定句,我们考虑模型检验的句子被限制到落在一组,一个自然的问题,然后分类哪些句子集是易处理的,哪些是难处理的。关于固定参数的易处理性,我们给出了一个一般定理,该定理将此分类问题简化为原始正逻辑的相应问题,用于各种结构的表示。这个一般定理允许我们推导出具有有界元的存在肯定句集是固定参数易处理的当且仅当每个句子等价于有界变量逻辑中的句子。然后,我们使用经典的复杂性的镜头来研究这些固定参数听话的句子集。我们表明,这样的一组可以是NP-完全的,并考虑从这样的一组句子的有界变量逻辑的翻译所需的长度,我们证明了这个长度的超多项式下界使用可编译性理论,获得一个有趣的类型的公式大小下界。总的来说,本文的工具、概念和结果为将来考虑在表达性更强的逻辑上进行模型检验的复杂性奠定了基础。

英文摘要:

We systematically investigate the complexity of model checking the existential positive fragment of first-order logic. In particular, for a set of existential positive sentences, we consider model checking where the sentence is restricted to fall into the set; a natural question is then to classify which sentence sets are tractable and which are intractable. With respect to fixed-parameter tractability, we give a general theorem that reduces this classification question to the corresponding question for primitive positive logic, for a variety of representations of structures. This general theorem allows us to deduce that an existential positive sentence set having bounded arity is fixed-parameter tractable if and only if each sentence is equivalent to one in bounded-variable logic. We then use the lens of classical complexity to study these fixed-parameter tractable sentence sets. We show that such a set can be NP-complete, and consider the length needed by a translation from sentences in such a set to bounded-variable logic; we prove superpolynomial lower bounds on this length using the theory of compilability, obtaining an interesting type of formula size lower bound. Overall, the tools, concepts, and results of this article set the stage for the future consideration of the complexity of model checking on more expressive logics.

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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