  An edit distance is a metric between words that quantifies how two words
differ by counting the number of edit operations needed to transform one word
into the other one. A word f is said isometric with respect to an edit distance
if, for any pair of f-free words u and v, there exists a transformation of
minimal length from u to v via the related edit operations such that all the
intermediate words are also f-free. The adjective 'isometric' comes from the
fact that, if the Hamming distance is considered (i.e., only mismatches), then
isometric words are connected with definitions of isometric subgraphs of
hypercubes. We consider the case of edit distance with swap and mismatch. We
compare it with the case of mismatch only and prove some properties of
isometric words that are related to particular features of their overlaps.
