Subwords and Power-Free Words are not Expressible by Word Equations
نویسنده
چکیده
We consider several open problems of Karhum aki, Mignosi, and Plandowski, cf. [KMP], concerning the expressibility of languages and relations as solutions of word equations. We show rst that the (scattered) subword relation is not expressible. Then, we consider the set of k-power free nite words and solve it negativelly for all nontrivial integer values of k. Finally, we consider the Fibonacci nite words. We do not solve the problem of the expressibility of the set of these words but prove that it cannot be given a negative answer (as believed) using the tools in [KMP].
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ورودعنوان ژورنال:
- Fundam. Inform.
دوره 38 شماره
صفحات -
تاریخ انتشار 1999