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- Marien Abreu, A. A. Diwan, Bill Jackson, Domenico Labbate, John Sheehan
- J. Comb. Theory, Ser. B
- 2008

A graph is pseudo 2–factor isomorphic if the numbers of circuits of length congruent to zero modulo four in each of its 2–factors, have the same parity. We prove that there exist no pseudo 2–factor isomorphic 1 2 Pseudo 2–Factor Isomorphic k–regular bipartite graphs for k ≥ 4. We also propose a characterization for 3-connected pseudo 2–factor isomorphic… (More)

- Marien Abreu, Martin Funk, Domenico Labbate, Vito Napolitano
- Discrete Mathematics
- 2008

- Marien Abreu, Camino Balbuena, Domenico Labbate
- Des. Codes Cryptography
- 2010

- Marien Abreu, Domenico Labbate, John Sheehan
- Des. Codes Cryptography
- 2012

A bipartite graph is pseudo 2–factor isomorphic if all its 2–factors have the same parity of number of circuits. In a previous paper we have proved that pseudo 2–factor isomorphic k–regular bipartite graphs exist only for k ≤ 3, and partially characterized them. In particular we proved that the only essentially 4–edge-connected pseudo 2–factor isomor-phic… (More)

- Marien Abreu, Gabriela Araujo-Pardo, Camino Balbuena, Domenico Labbate, Julián Salas
- Electronic Notes in Discrete Mathematics
- 2012

In this paper we obtain (q + 3)–regular graphs of girth 5 with fewer vertices than previously known ones for q = 13, 17, 19 and for any prime q ≥ 23 performing operations of reductions and amalgams on the Levi graph Bq of an elliptic semiplane of type C. We also obtain a 13–regular graph of girth 5 on 236 vertices from B11 using the same technique.

- Marien Abreu, Robert E. L. Aldred, Martin Funk, Bill Jackson, Domenico Labbate, John Sheehan
- J. Comb. Theory, Ser. B
- 2004

We show that a digraph which contains a directed 2-factor and has minimum in-degree and out-degree at least four has two non-isomorphic directed 2-factors. As a corollary we deduce that every graph which contains a 2-factor and has minimum degree at least eight has two non-isomorphic 2-factors. In addition we construct: an infinite family of strongly… (More)

- Marien Abreu, Martin Funk, Domenico Labbate, Vito Napolitano
- Ars Comb.
- 2008

- Marien Abreu, Robert E. L. Aldred, Martin Funk, Bill Jackson, Domenico Labbate, John Sheehan
- J. Comb. Theory, Ser. B
- 2009

- Marien Abreu, Domenico Labbate, John Sheehan
- Eur. J. Comb.
- 2012

- Marien Abreu, Domenico Labbate, Romeo Rizzi, John Sheehan
- Eur. J. Comb.
- 2014

A snark is a cubic cyclically 4–edge connected graph with edge chromatic number four and girth at least five. We say that a graph G is odd 2–factored if for each 2–factor F of G each cycle of F is odd. In this paper, we present a method for constructing odd 2–factored snarks. In particular, we construct two new odd 2–factored snarks that disprove a… (More)