Zebra Factorizations in Free Semigroups
نویسندگان
چکیده
Let be a semigroup of words over an alphabet . Let consist of those elements of for which every prefix and suffix of belongs to . We show that is a free semigroup. Moreover, is called separative if also the complement is a semigroup. There are uncountably many separative semigroups over , if has at least two letters. We prove that if is separative, then every word has a unique minimum factorization with respect to and , where and is as small as possible.
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