activity
20212026
most citedProblems, proofs, and disproofs on the inversion number

3 citations · 7 across the 15 of their papers we have counts for

collaborators

17 papers

math.CO2026

Clique Number of Tournaments II

Guillaume Aubian, Samuel Coulomb

The directed clique number of a tournament is the minimum, over all orderings of the vertices of , of the clique number of the graph whose edges are the arcs that…

math.CO2026

(Claw, C_3)-free digraphs with unbounded dichromatic number

Guillaume Aubian, Luis Kuffner

We construct orientations of rook graphs (whose underlying graphs are claw-free) that contain no directed but have unbounded dichromatic number. This disproves a conjecture o…

math.CO2025

Extension of the Gyárfás-Sumner conjecture to signed graphs

Guillaume Aubian, Allen Ibiapina, Luis Kuffner +4

The balanced chromatic number of a signed graph G is the minimum number of balanced sets that cover all vertices of G. Studying structural conditions which imply bounds on the bala…

math.CO2025

On cuts of small chromatic number in sparse graphs

Guillaume Aubian, Marthe Bonamy, Romain Bourneuf +2

For a given integer , let denote the supremum such that every sufficiently large graph with average degree less than admits a separator $X \subseteq…

cs.DS2025

Complexity Gaps between Point and Interval Temporal Graphs for some Reachability Problems

Guillaume Aubian, Filippo Brunelli, Feodor F Dragan +4

Temporal graphs arise when modeling interactions that evolve over time. They usually come in several flavors, depending on the number of parameters used to describe the temporal as…

math.CO2024

Finding forest-orderings of tournaments is NP-complete

Pierre Aboulker, Guillaume Aubian, Raul Lopes

Given a class of (undirected) graphs , we say that a Feedback Arc Set (FAS for short) is a -FAS if the graph induced by the edges of (forgetting t…

math.CO2024

Computing the clique number of tournaments

Guillaume Aubian

The clique number of a tournament is the maximum clique number of a graph formed by keeping backwards arcs in an ordering of its vertices. We study the time complexity of computing…

math.CO2023

Clique number of tournaments

Pierre Aboulker, Guillaume Aubian, Pierre Charbit +1

Given a digraph together with an ordering of its vertices, the \emph{backedge graph} of with respect to is the undirected graph with the same ve…

math.CO2023

Colouring Digraphs

Guillaume Aubian

The aim of this thesis is to investigate how the structure of a digraph affects its dichromatic number and to extend various results on undirected colouring to digraphs. In the fir…

math.CO2023

Digraph Colouring and Arc-Connectivity

Pierre Aboulker, Guillaume Aubian, Pierre Charbit

The dichromatic number of a digraph is the minimum size of a partition of its vertices into acyclic induced subgraphs. We denote by the maximum local edge con…

math.CO2023★ 1 cited

(P6, triangle)-free digraphs have bounded dichromatic number

Pierre Aboulker, Guillaume Aubian, Pierre Charbit +1

The dichromatic number of an oriented graph is the minimum size of a partition of its vertices into acyclic induced subdigraphs. We prove that oriented graphs with no induced direc…

math.CO2022★ 3 cited

Problems, proofs, and disproofs on the inversion number

Guillaume Aubian, Frédéric Havet, Florian Hörsch +4

The {\it inversion} of a set of vertices in a digraph consists in reversing the direction of all arcs of . The {\it inversion number} of an oriented grap…

math.CO2022★ 1 cited

Heroes in orientations of chordal graphs

Pierre Aboulker, Guillaume Aubian, Raphael Steiner

We characterize all digraphs such that orientations of chordal graphs with no induced copy of have bounded dichromatic number.

math.CO2022

Vizing's and Shannon's Theorems for defective edge colouring

Pierre Aboulker, Guillaume Aubian, Chien-Chung Huang

We call a multigraph -edge colourable if its edge set can be partitioned into subgraphs of maximum degree at most and denote as the minimum such that…

math.CO2022★ 1 cited

Heroes in oriented complete multipartite graphs

Pierre Aboulker, Guillaume Aubian, Pierre Charbit

The dichromatic number of a digraph is the minimum size of a partition of its vertices into acyclic induced subgraphs. Given a class of digraphs , a digraph is a he…

cs.DM2021

Four proofs of the directed Brooks' Theorem

Pierre Aboulker, Guillaume Aubian

We give four new proofs of the directed version of Brook's Theorem and an NP-completeness result.

math.CO2021★ 1 cited

Decomposing and colouring some locally semicomplete digraphs

Pierre Aboulker, Guillaume Aubian, Pierre Charbit

A digraph is semicomplete if any two vertices are connected by at least one arc and is locally semicomplete if the out-neighbourhood and the in-neighbourhood of any vertex induce a…