,
Aliaume Lopez
Creative Commons Attribution 4.0 International license
We study classes of graphs with bounded clique-width that are well-quasi-ordered by the induced subgraph relation, in the presence of labels on the vertices. We prove that, given a finite presentation of a class of graphs, one can decide whether the class is labelled-well-quasi-ordered. This answers positively to two conjectures of Pouzet in the restricted case of bounded clique-width classes. Namely, we prove that being labelled-well-quasi-ordered by a set of size 2 or by a well-quasi-ordered infinite set are equivalent conditions, and that in such cases, one can freely assume that the graphs are equipped with a total ordering on their vertices. Finally, we provide a structural characterization of those classes as those that are of bounded clique-width and do not existentially transduce the class of all finite paths.
@InProceedings{dumas_et_al:LIPIcs.LICS.2026.38,
author = {Dumas, Ma\"{e}l and Lopez, Aliaume},
title = {{Well-Quasi-Ordered Classes of Bounded Clique-Width}},
booktitle = {41st Annual Symposium on Logic in Computer Science (LICS 2026)},
pages = {38:1--38:24},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-434-5},
ISSN = {1868-8969},
year = {2026},
volume = {380},
editor = {Faggian, Claudia and Katoen, Joost-Pieter},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.LICS.2026.38},
URN = {urn:nbn:de:0030-drops-268257},
doi = {10.4230/LIPIcs.LICS.2026.38},
annote = {Keywords: well-quasi-ordering, clique-width, automata theory, monoids, factorization forests, gap embedding}
}