Covering Problems from a Formal Language Point of View
We consider the formal language of all words that are ‘covered’ by words in a given language. This language is said cov-free when any word has at most one minimal covering over it. We study the notion of cov-freeness in relation with its counterpart in classical monoids and in monoids of zig-zag factorizations. In particular cov-freeness is characterized by the here introduced notion of cov-stability. Some more properties are obtained using this characterization. We also show that the series counting the minimal coverings of a word over a regular language is rational.
KeywordsCovering Problem Regular Language Minimal Covering Classical Stability Covering Code
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