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arXiv 1802.04708cs.FLcs.CC
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不确定有限自动机可接受词的分类

Lengths of Words Accepted by Nondeterministic Finite Automata

Aaron Potechin, Jeffrey Shallit

摘要:

我们考虑了两个关于非确定有限自动机的自然问题。首先,给定这样一个有n个状态的自动机M,长度为l,M是否接受长度为l的字?我们证明了经典的无三角形图识别问题可归结为无三角形图识别问题,并给出了一个O(n^ω(log n)^{1+ε} log l)时间的算法来解决它,其中ω是矩阵乘法的最优指数.第二,假设L(M)是有限的,我们考虑列出M所接受的所有字的长度的问题。虽然这个问题看起来可能要困难得多,但我们证明了这个问题可以在O(n^ω(log n)^{2+ε})时间内解决。最后,我们给出了NFA接受和强指数时间假设之间的联系。

英文摘要:

We consider two natural problems about nondeterministic finite automata. First, given such an automaton M of n states, and a length l, does M accept a word of length l? We show that the classic problem of triangle-free graph recognition reduces to this problem, and give an O(n^ω (log n)^{1+ε} log l)-time algorithm to solve it, where ω is the optimal exponent for matrix multiplication. Second, provided L(M) is finite, we consider the problem of listing the lengths of all words accepted by M. Although this problem seems like it might be significantly harder, we show that this problem can be solved in O(n^ω(log n)^{2+ε}) time. Finally, we give a connection between NFA acceptance and the strong exponential-time hypothesis.

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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