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On the class of languages recognizable by 1-way quantum finite automata

Andris Ambainis·Arnolds Kikusts·Maris Valdats
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Abstract

It is an open problem to characterize the class of languages recognized by quantum finite automata (QFA). We examine some necessary and some sufficient conditions for a (regular) language to be recognizable by a QFA. For a subclass of regular languages we get a condition which is necessary and sufficient. Also, we prove that the class of languages recognizable by a QFA is not closed under union or any other binary Boolean operation where both arguments are significant.

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Andris Ambainis, Arnolds Kikusts, Maris Valdats. 2000-09-01. On the class of languages recognizable by 1-way quantum finite automata. https://arxiv.org/abs/quant-ph/0009004

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