Using unavoidable set of trees to generalize Kruskal's theorem
Journal of Symbolic Computation
Well quasi-orders and regular languages
Acta Informatica
On quasi orders of words and the confluence property
Theoretical Computer Science
On well quasi orders of free monoids
Theoretical Computer Science - Special issue: papers dedicated to the memory of Marcel-Paul Schützenberger
Shuffle and scattered deletion closure of languages
Theoretical Computer Science
Well quasi-orders and context-free grammars
Theoretical Computer Science - Developments in language theory
Regular solutions of language inequalities and well quasi-orders
Theoretical Computer Science - Automata, languages and programming: Algorithms and complexity (ICALP-A 2004)
On well quasi-orders on languages
DLT'03 Proceedings of the 7th international conference on Developments in language theory
The power of commuting with finite sets of words
STACS'05 Proceedings of the 22nd annual conference on Theoretical Aspects of Computer Science
| Hi-index | 5.23 |
Given a set I of words, the set L"@?"""I^@e of all words obtained by the shuffle of (copies of) words of I is naturally provided with a partial order: for u,v in L"@?"""I^@e, u@?"I^*v if and only if v is the shuffle of u and another word of L"@?"""I^@e. In [F. D'Alessandro, S. Varricchio, Well quasi-orders, unavoidable sets and derivation systems, in: Word Avoidability Complexity and Morphisms (WACAM), RAIRO Theoretical Informatics and Applications 40 (3) (2006) 407-426 (special issue)], the authors have opened the problem of the characterization of the finite sets I such that @?"I^* is a well quasi-order on L"@?"""I^@e. In this paper we give an answer in the case when I consists of a single word w.