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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…

Combinatorics · Mathematics 2026-05-29 Maël Dumas , Aliaume Lopez

We are interested in characterizing which classes of finite graphs are well-quasi-ordered by the induced subgraph relation. To that end, we devise an algorithm to decide whether a class of finite graphs well-quasi-ordered by the induced…

Logic in Computer Science · Computer Science 2024-07-02 Aliaume Lopez

We consider well-quasi-order for classes of permutation graphs which omit both a path and a clique. Our principle result is that the class of permutation graphs omitting $P_5$ and a clique of any size is well-quasi-ordered. This is proved…

Combinatorics · Mathematics 2015-04-28 Aistis Atminas , Robert Brignall , Nicholas Korpelainen , Vadim Lozin , Vincent Vatter

A well-quasi-order is an order which contains no infinite decreasing sequence and no infinite collection of incomparable elements. In this paper, we consider graph classes defined by excluding one graph as contraction. More precisely, we…

Combinatorics · Mathematics 2016-12-20 Marcin Kamiński , Jean-Florent Raymond , Théophile Trunck

The juxtaposition of permutation classes $\mathcal{C}$ and $\mathcal{D}$ is the class of all permutations formed by concatenations $\sigma\tau$, such that $\sigma$ is order isomorphic to a permutation in $\mathcal{C}$, and $\tau$ to a…

Combinatorics · Mathematics 2023-12-20 Robert Brignall

In this paper we consider the question of well quasi-order for classes defined by a single obstruction within the classes of all graphs, digraphs and tournaments, under the homomorphic image ordering (in both its standard and strong forms).…

Combinatorics · Mathematics 2017-03-17 N. Ruskuc , Sophie Huczynska

We present a hereditary class of graphs of unbounded clique-width which is well-quasi-ordered by the induced subgraph relation. This result provides a negative answer to the question asked by Daligault, Rao and Thomass\'e in…

Discrete Mathematics · Computer Science 2015-03-03 Vadim Lozin , Igor Razgon , Viktor Zamaraev

The well-quasi-orders (WQO) play an important role in various fields such as Computer Science, Logic or Graph Theory. Since the class of WQOs lacks closure under some important operations, the proof that a certain quasi-order is WQO…

Logic · Mathematics 2024-10-18 Yann Pequignot

Korpelainen, Lozin, and Razgon conjectured that a hereditary property of graphs which is well-quasi-ordered by the induced subgraph order and defined by only finitely many minimal forbidden induced subgraphs is labelled well-quasi-ordered,…

Combinatorics · Mathematics 2018-10-08 Robert Brignall , Michael Engen , Vincent Vatter

Daligault, Rao and Thomass\'e asked whether a hereditary class of graphs well-quasi-ordered by the induced subgraph relation has bounded clique-width. Lozin, Razgon and Zamaraev recently showed that this is not true for classes defined by…

Combinatorics · Mathematics 2016-11-14 Konrad K. Dabrowski , Vadim V. Lozin , Daniël Paulusma

The central theorem of topological graph theory states that the graph minor relation is a well-quasi-order on graphs. It has far-reaching consequences, in particular in the study of graph structures and the design of (parameterized)…

Computational Geometry · Computer Science 2025-12-04 Corentin Lunel , Clément Maria

We study bipartite graphs partially ordered by the induced subgraph relation. Our goal is to distinguish classes of bipartite graphs which are or are not well-quasi-ordered (wqo) by this relation. Answering an open question from…

Combinatorics · Mathematics 2010-05-11 Nicholas Korpelainen , Vadim V. Lozin

Well-quasi orders such as homeomorphic embedding are commonly used to ensure termination of program analysis and program transformation, in particular supercompilation. We compare eight well-quasi orders on how discriminative they are and…

Programming Languages · Computer Science 2013-09-23 Torben Æ. Mogensen

It is known that the set of permutations, under the pattern containment ordering, is not a partial well-order. Characterizing the partially well-ordered closed sets (equivalently: down sets or ideals) in this poset remains a wide-open…

Combinatorics · Mathematics 2007-05-23 Maximillian Murphy , Vincent Vatter

Balogh, Bollobas and Weinreich showed that a parameter that has since been termed the distinguishing number can be used to identify a jump in the possible speeds of hereditary classes of graphs at the sequence of Bell numbers. We prove that…

Combinatorics · Mathematics 2019-05-13 Aistis Atminas , Robert Brignall

Every better quasi-order codifies a Borel graph that does not contain a copy of the shift graph. It is known that there is a better quasi-order that codes a Borel graph with infinite Borel chromatic number, though one has yet to be…

Logic · Mathematics 2021-01-15 Keegan Dasilva Barbosa

The class of quasi-chain graphs is an extension of the well-studied class of chain graphs. This latter class enjoys many nice and important properties, such as bounded clique-width, implicit representation, well-quasi-ordering by induced…

Combinatorics · Mathematics 2021-04-12 Bogdan Alecu , Aistis Atminas , Vadim Lozin , Dmitriy Malyshev

Here it is shown that standard set theory can be interpreted in a theory about order. The ordering here is about non-extensional flat classes, i.e. classes that are not elements of classes. So, stipulating a nearly well order over all those…

Logic · Mathematics 2023-12-20 Zuhair Al-Johar

We consider partially ordered sets of combinatorial structures under consecutive orders, meaning that two structures are related when one embeds in the other such that `consecutive' elements remain consecutive in the image. Given such a…

Combinatorics · Mathematics 2026-04-22 Victoria Ironmonger , Nik Ruškuc

In this work, we improve the accuracy of several known algorithms to address the classification of large datasets when few labels are available. Our framework lies in the realm of graph-based semi-supervised learning. With novel…

Machine Learning · Computer Science 2024-07-02 Farid Bozorgnia
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