A. Boussairi

activity

20112024

most citedPrime bound of a graph

2 citations · 2 across the 9 of their papers we have counts for

collaborators

11 papers

math.CO2024

Quasi-orthogonal extension of symmetric matrices

Abderrahim Boussaïri, Brahim Chergui, Zaineb Sarir +1

An $n \times n$ real matrix $Q$ is quasi-orthogonal if $Q^{⊤} Q = q I_{n}$ for some positive real number $q$ . If $M$ is a principal sub-matrix of a quasi-orthogonal matrix $Q$ , we sa…

math.CO2024

Quasi-orthogonal extension of skew-symmetric matrices

Abderrahim Boussaïri, Brahim Chergui, Zaineb Sarir +1

A real matrix $Q$ is quasi-orthogonal if $Q^{⊤} Q = q I$ , for some positive real number $q$ . We prove that any $n \times n$ skew-symmetric matrix $S$ is a principal sub-matrix of a s…

math.CO2020

Critical 3-hypergraphs (detailed version)

Abderrahim Boussairi, Brahim Chergui, Pierre Ille +1

Given a 3-hypergraph $H$ , a subset $M$ of $V (H)$ is a module of $H$ if for each $e \in E (H)$ such that $e \cap M \neq = \emptyset$ and $e ∖ M \neq = \emptyset$ , there exists $m \in M$ …

math.CO2019

On the spectral reconstruction problem for digraphs

Edward Bankoussou-mabiala, Abderrahim Boussaïri, Abdelhak Chaïchaâ +2

The idiosyncratic polynomial of a graph $G$ with adjacency matrix $A$ is the characteristic polynomial of the matrix $A + y (J - A - I)$ , where $I$ is the identity matrix and $J$ is th…

math.CO2019

The simplicity index of tournaments

Abderrahim Boussaïri, Soufiane Lakhlifi, Imane Talbaoui

An $n$ -tournament $T$ with vertex set $V$ is simple if there is no subset $M$ of $V$ such that $2 \leq ∣ M ∣ \leq n - 1$ and for every $x \in V ∖ M$ , either…

math.CO2018

An exact extremal result for tournaments and 4-uniform hypergraphs

Wiam Belkouche, Abderrahim Boussaïri, Soufiane Lakhlifi +1

In this paper, we address the following problem due to Frankl and Füredi (1984). What is the maximum number of hyperedges in an $r$ -uniform hypergraph with $n$ vertices, such that…

math.CO2016

A matrix description of weakly bipartitive and bipartitive families

Edward Bankoussou-mabiala, Abderrahim Boussaïri, Abdelhak Chaïchaâ +1

The notions of weakly bipartitive and bipartitive families were introduced by Montgolfier (2003) as a general tool for studying some decomposition of graphs and other combinatorial…

math.CO2016

A transformation that preserves principal minors of skew-symmetric matrices

Abderrahim Boussaïri, Brahim Chergui

Our motivation comes from the work of Engel and Schneider (1980). Their main theorem implies that two symmetric matrices have equal corresponding principal minors of all orders if…

math.CO2015

About the spectra of a real nonnegative matrix and its signings

Kawtar Attas, Abderrahim Boussaïri, Mohamed Zaidi

For a real matrix $M$ , we denote by $s p (M)$ the spectrum of $M$ and by $∣ M ∣$ its absolute value, that is the matrix obtained from $M$ by replacing each entry…

math.CO2014

Skew-symmetric matrices and their principal minors

A. Boussairi, B. Chergui

Let $V$ be a nonempty finite set and $A = (a_{ij})_{i, j \in V}$ be a matrix with entries in a field $K$ . For a subset $X$ of $V$ , we denote by $A [X]$ the submatrix of $A$ hav…

math.CO2011★ 2 cited

Prime bound of a graph

Abderrahim Boussaïri, Pierre Ille

Given a graph G, a subset M of V (G) is a module of G if for each v \in V (G) \diagdownM, v is adjacent to all the elements of M or to none of them. For instance, V(G), \varnothing…