ON SUBWORD SYMMETRY OF WORDS
Anton Černý · International Journal of Foundations of Computer Science · 2008
We call a word L-symmetric with respect to a finite language L if it contains the same number of scattered subwords u as of uR for every word u from L. We show that increasing the size of the language L may lead to an unlimited refinement of the language of L-symmetric words. Further we prove that if a long enough initial segment of a D0L-sequence consists entirely of L-symmetric words, then all words in the sequence are L-symmetric.