Marién Abreu

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6ranked-venue papers
6as first author
3since 2021 · last 2026
0000-0003-3992-1029ORCID · verified

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Security and privacy · 3 · 3 first-author · 1 since 2021Theory of computation · 3 · 3 first-author · 2 since 2021
YearPublicationVenuePosition
2026 The Gray graph is pseudo 2-factor isomorphic
abstract
A graph is pseudo 2-factor isomorphic if all of its 2-factors have the same parity of number of cycles. Abreu et al. (2008) conjectured that K3,3 , the Heawood graph and the Pappus graph are the only essentially 4-edge-connected pseudo 2-factor isomorphic cubic bipartite graphs. This conjecture was disproved by Goedgebeur (2015) who constructed a coun- terexample G (of girth 6) on 30 vertices. Using a computer search, he also showed that this is the only counterexample up to at least 40 vertices and that there are no counterexamples of girth greater than 6 up to at least 48 vertices. In this manuscript, we show that the Gray graph – which has 54 vertices and girth 8 – is also a counterexample to the pseudo 2-factor isomorphic graph conjecture. Next to the graph G, this is the only other known counterexample. Using a computer search, we show that there are no smaller counterexamples of girth 8 and show that there are no other counterexamples up to at least 42 vertices of any girth. Moreover, we also verified that there are no further counterexamples among the known censuses of symmetrical graphs. Recall that a graph is 2-factor Hamiltonian if all of its 2-factors are Hamiltonian cycles. As a by-product of the computer searches performed for this paper, we have verified that the 2-factor Hamiltonian conjecture of Funk et al. (2003), which is still open, holds for cubic bipartite graphs of girth at least 8 up to 52 vertices, and up to 42 vertices for any girth.
Marién Abreu, Jan Goedgebeur, Jorik Jooken, Federico Romaniello, Tibo Van den Eede
Discret. Appl. Math.1
2023 A construction for a counterexample to the pseudo 2-factor isomorphic graph conjecture
Marién Abreu, Martin Funk, Domenico Labbate, Federico Romaniello
Discret. Appl. Math.1
2022 Strongly regular configurations
Marién Abreu, Martin Funk, Vedran Krcadinac, Domenico Labbate
Des. Codes Cryptogr.1
2018 A note on 2-bisections of claw-free cubic graphs
Marién Abreu, Jan Goedgebeur, Domenico Labbate, Giuseppe Mazzuoccolo
Discret. Appl. Math.1
2012 Irreducible pseudo 2-factor isomorphic cubic bipartite graphs
Marién Abreu, Domenico Labbate, John Sheehan
Des. Codes Cryptogr.1
2010 Adjacency matrices of polarity graphs and of other C4-free graphs of large size
Marién Abreu, Camino Balbuena, Domenico Labbate
Des. Codes Cryptogr.1