文章基本信息

标题：Bidirectional Nested Weighted Automata
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作者：Krishnendu Chatterjee ; Thomas A. Henzinger ; Jan Otop 等
期刊名称：LIPIcs : Leibniz International Proceedings in Informatics
电子版ISSN：1868-8969
出版年度：2017
卷号：85
页码：5:1-5:16
DOI：10.4230/LIPIcs.CONCUR.2017.5
出版社：Schloss Dagstuhl -- Leibniz-Zentrum fuer Informatik
摘要：Nested weighted automata (NWA) present a robust and convenient automata-theoretic formalism for quantitative specifications. Previous works have considered NWA that processed input words only in the forward direction. It is natural to allow the automata to process input words backwards as well, for example, to measure the maximal or average time between a response and the preceding request. We therefore introduce and study bidirectional NWA that can process input words in both directions. First, we show that bidirectional NWA can express interesting quantitative properties that are not expressible by forward-only NWA. Second, for the fundamental decision problems of emptiness and universality, we establish decidability and complexity results for the new framework which match the best-known results for the special case of forward-only NWA. Thus, for NWA, the increased expressiveness of bidirectionality is achieved at no additional computational complexity. This is in stark contrast to the unweighted case, where bidirectional finite automata are no more expressive but exponentially more succinct than their forward-only counterparts.
关键词：weighted automata; nested weighted automata; complexity; bidirectional