一句话:提出极大迁移与预序稳定性,为一系列高效模拟算法奠基,并给出首个兼顾时间与空间复杂度的最粗模拟预序算法。
计算包含于给定初始预序的最粗模拟预序 ℛ_sim 常用于约简 Kripke 结构、标记图、标记迁移系统以及字/树自动机等模型的状态空间。已有算法要么内存高效、要么时间高效,难以兼得。本文提出极大迁移与预序相对于更粗预序的稳定性两个概念,为设计一系列高效模拟算法奠定基础。作为示例,作者给出首个兼具最佳已发表时间复杂度 O(|P_sim|·|→|) 和 bit 空间复杂度 O(|P_sim|^2 log|P_sim| + |Q| log|Q|) 的算法,其中 P_sim 是 ℛ_sim 诱导的划分,从而解决了一个开放问题。
Compute the coarsest simulation preorder included in an initial preorder is used to reduce the resources needed to analyze a given transition system. This technique is applied on many models like Kripke structures, labeled graphs, labeled transition systems or even word and tree automata. Let (Q,→) be a given transition system and ℛ<inf>init</inf> be an initial preorder over Q. Until now, algorithms to compute ℛ<inf>sim</inf>, the coarsest simulation included in ℛ<inf>init</inf>, are either memory efficient or time efficient but not both. In this paper we propose the foundation for a series of efficient simulation algorithms with the introduction of the notion of maximal transitions and the notion of stability of a preorder with respect to a coarser one. As an illustration we solve an open problem by providing the first algorithm with the best published time complexity, O(|P<inf>sim</inf>|.|→|), and a bit space complexity in O(|P<inf>sim</inf>|<sup>2</sup>.log(|P<inf>sim</inf>|)+|Q|.log(|Q|)), with P<inf>sim</inf> the partition induced by ℛ<inf>sim</inf>.