Well quasi-orders and the shuffle closure of finite sets
<|reference_start|>Well quasi-orders and the shuffle closure of finite sets: Given a set I of word, the set of all words obtained by the shuffle of (copies of) words of I is naturally provided with a partial order. In [FS05], the authors have opened the problem of the characterization of the finite sets I such that the order is a well quasi-order . In this paper we give an answer in the case when I consists of a single word w.<|reference_end|>
@article{d'alessandro2006well,
    title={Well quasi-orders and the shuffle closure of finite sets},
    author={Flavio D'Alessandro, Gw'ena"el Richomme (LaRIA), Stefano Varrichio},
    journal={arXiv preprint arXiv:cs/0607082},
    year={2006},
    archivePrefix={arXiv},
    eprint={cs/0607082},
    primaryClass={cs.DM}
}