On the regularity of languages on a binary alphabet generated by copying systems
Information Processing Letters
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
Finiteness and Regularity in Semigroups and Formal Languages
Finiteness and Regularity in Semigroups and Formal Languages
Some Regularity Conditions Based on Well Quasi-Orders
LATIN '92 Proceedings of the 1st Latin American Symposium on Theoretical Informatics
Well quasi-orders generated by a word-shuffle rewriting
Theoretical Computer Science
Well Quasi-orders in Formal Language Theory
DLT '08 Proceedings of the 12th international conference on Developments in Language Theory
A characterization of (regular) circular languages generated by monotone complete splicing systems
Theoretical Computer Science
Avoidable sets and well quasi-orders
DLT'04 Proceedings of the 8th international conference on Developments in Language Theory
Well quasi orders and the shuffle closure of finite sets
DLT'06 Proceedings of the 10th international conference on Developments in Language Theory
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Let G be a context-free grammar and let L be the language of all the words derived from any variable of G. We prove the following generalization of Higman's theorem: any division order on L is a well quasi-order on L. We also give applications of this result to some quasi-orders associated with unitary grammars.