文章基本信息

标题：The Keys to Decidable HyperLTL Satisfiability: Small Models or Very Simple Formulas
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作者：Corto Mascle ; Martin Zimmermann
期刊名称：LIPIcs : Leibniz International Proceedings in Informatics
电子版ISSN：1868-8969
出版年度：2020
卷号：152
页码：1-16
DOI：10.4230/LIPIcs.CSL.2020.29
出版社：Schloss Dagstuhl -- Leibniz-Zentrum fuer Informatik
摘要：HyperLTL, the extension of Linear Temporal Logic by trace quantifiers, is a uniform framework for expressing information flow policies by relating multiple traces of a security-critical system. HyperLTL has been successfully applied to express fundamental security policies like noninterference and observational determinism, but has also found applications beyond security, e.g., distributed protocols and coding theory. However, HyperLTL satisfiability is undecidable as soon as there are existential quantifiers in the scope of a universal one. To overcome this severe limitation to applicability, we investigate here restricted variants of the satisfiability problem to pinpoint the decidability border. First, we restrict the space of admissible models and show decidability when restricting the search space to models of bounded size or to finitely representable ones. Second, we consider formulas with restricted nesting of temporal operators and show that nesting depth one yields decidability for a slightly larger class of quantifier prefixes. We provide tight complexity bounds in almost all cases.
关键词：Hyperproperties; Linear Temporal Logic; Satisfiability