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arXiv 1706.01668cs.FLcs.LO
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双向词转换器的一向可定义性

One-way definability of two-way word transducers

Félix Baschenis, Olivier Gauwin, Anca Muscholl, Gabriele Puppis

AI总结:

本文针对双向词转换器是否可由单向转换器实现的问题,提出一种双指数空间复杂度的新算法,并在扫描转换器情形下将复杂度降低一个指数,同时给出最优构造。

摘要:

由双向转换器(或等价地,由流式转换器或MSO转换)实现的功能性转换,是从词到词的“正则”映射的自然且标准的概念。2013年已证明,判断这种转换是否可由某个单向转换器实现是可判定的,但所给出的算法具有非初等复杂度。我们提供了一种不同风格的算法来解决上述问题,其空间复杂度为双指数。在扫描转换器的特殊情况下,复杂度降低一个指数。我们还展示了如何构造一个等价的双向转换器(若存在),其时间复杂度为双指数或三指数,具体取决于输入转换器是扫描式还是双向式。在扫描情况下,我们的构造被证明是最优的。

英文摘要:

Functional transductions realized by two-way transducers (or, equally, by streaming transducers or MSO transductions) are the natural and standard notion of "regular" mappings from words to words. It was shown in 2013 that it is decidable if such a transduction can be implemented by some one-way transducer, but the given algorithm has non-elementary complexity. We provide an algorithm of different flavor solving the above question, that has doubly exponential space complexity. In the special case of sweeping transducers the complexity is one exponential less. We also show how to construct an equivalent one-way transducer, whenever it exists, in doubly or triply exponential time, again depending on whether the input transducer is sweeping or two-way. In the sweeping case our construction is shown to be optimal.

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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