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arXiv 1004.1845cs.LOmath.LO
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嵌套序列

Nested Sequents

Kai Brünnler

摘要:

我们看到如何嵌套序列,超序列的自然概括,使我们能够开发一个系统的模态逻辑证明理论。与其他突出的形式主义,如显示演算和标记序列相反,嵌套序列留在模态语言中,并允许在字面意义上享受子公式属性的证明系统。在第一部分中,我们研究了一套系统的嵌套系统的所有正常模态逻辑形成的一些组合的公理的序列性,自反性,对称性,传递性和欧几里德。我们建立健全性和完整性和他们的一些良好的性质,如可逆的所有规则,结构规则的可接受性,终止证明搜索,以及句法切割消除。在第二部分中,我们研究了常识逻辑,一种具有不动点模态的模态逻辑。我们期待在两个无穷证明系统,这种逻辑:现有的一个普通序列的基础上,没有语法切割消除程序是已知的,和一个新的嵌套序列的基础上。我们看到如何嵌套的序列,在普通的序列相比,允许句法削减消除,从而使我们能够获得一个序数上限的长度证明。

英文摘要:

We see how nested sequents, a natural generalisation of hypersequents, allow us to develop a systematic proof theory for modal logics. As opposed to other prominent formalisms, such as the display calculus and labelled sequents, nested sequents stay inside the modal language and allow for proof systems which enjoy the subformula property in the literal sense. In the first part we study a systematic set of nested sequent systems for all normal modal logics formed by some combination of the axioms for seriality, reflexivity, symmetry, transitivity and euclideanness. We establish soundness and completeness and some of their good properties, such as invertibility of all rules, admissibility of the structural rules, termination of proof-search, as well as syntactic cut-elimination. In the second part we study the logic of common knowledge, a modal logic with a fixpoint modality. We look at two infinitary proof systems for this logic: an existing one based on ordinary sequents, for which no syntactic cut-elimination procedure is known, and a new one based on nested sequents. We see how nested sequents, in contrast to ordinary sequents, allow for syntactic cut-elimination and thus allow us to obtain an ordinal upper bound on the length of proofs.

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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