Subword balance, position indices and power sums
In this paper, we investigate various ways of characterizing words, mainly over a binary alphabet, using information about the positions of occurrences of letters in words. We introduce two new measures associated with words, the position index and sum of position indices. We establish some characterizations, connections with Parikh matrices, and connections with power sums. One particular emphasis concerns the effect of morphisms and iterated morphisms on words. (C) 2010 Elsevier Inc. All rights reserved.
subword power sum iterated morphism position of letter parikh matrix thue morphism fibonacci morphism