ISTI-CNR

Abstract. We consider a general shuing operation for ¯nite and in¯nite words which is not necessarily fair. This means that it may be the case that in a shue of two words, from some point onwards, one of these words prevails ad in¯nitum even though the other word still has letters to contribute. Pre¯xes and limits of shues are investigated, leading to a characterization of general shues in terms of shues of ¯nite words, a result which does not hold for fair shues. Associativity of shuing is an immediate corollary.