A. S. Razafimahatratra

activity

20182026

most citedOn triangles in derangement graphs

1 citations · 2 across the 23 of their papers we have counts for

collaborators

26 papers

math.CO2026

The automorphism group of the derangement graph of $PGL_{2} (q)$ acting on the projective line

Andriaherimanana Sarobidy Razafimahatratra

Given a finite transitive group $G \leq Sym (Ω)$ , the derangement graph $Γ_{G}$ is the graph whose vertex set is $G$ , and two vertices $g$ and $h$ are adjacent if the ra…

math.CO2025

The intersection densities of transitive actions of $PSL_{2} (q)$ with cyclic point stabilizers

Angelot Behajaina, Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Given a finite transitive group $G \leq Sym Ω$ , the {intersection density} of $G$ is defined as the ratio between the size of the largest subsets of $G$ in which any t…

math.CO2025

On the Terwilliger algebras of quasi-thin Schurian association schemes

Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

An association scheme is triply transitive if its automorphism group is transitive, and the centralizer algebra of a point stabilizer of its automorphism group coincides with the T…

math.CO2025

Perfect and multiple state transfer in oriented Cayley graphs

Ada Chan, Venkata Raghu Tej Pantangi, Andriaherimanana Sarobidy Razafimahatratra +1

We study perfect state transfer and multiple state transfer in oriented normal Cayley graphs. We construct examples in a variety of groups, ranging from abelian to nonsolvable, and…

math.CO2025

The intersection density of cubic arc-transitive graphs with $2$ -arc-regular full automorphism group equal to $PGL_{2} (q)$

Karen Meagher, Andriaherimanana Sarobidy Razafimahatratra

The \emph{intersection density} of a transitive permutation group $G \leq Sym (Ω)$ is the ratio between the largest size of a subset of $G$ in which any two agree on a…

math.CO2024

On the Terwilliger algebra of the group association scheme of the symmetric group $sym (7)$

Allen Herman, Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Terwilliger algebras are finite-dimensional semisimple algebras that were first introduced by Paul Terwilliger in 1992 in studies of association schemes and distance-regular graphs…

math.CO2024

On the maximum intersecting sets of the general semilinear group of degree $2$

Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Let $p$ be a prime and $q = p^{k}$ . A subset $F \subset ΓL_{2} (q)$ is intersecting if any two semilinear transformations in $F$ agree on some non-z…

math.CO2023

The Erdős-Ko-Rado Theorem for non-quasiprimitive groups of degree $3 p$

Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

The \emph{intersection density} of a finite transitive group $G \leq Sym (Ω)$ is the rational number $ρ (G)$ given by the ratio between the maximum size of a subset of…

math.CO2023

On cocliques in commutative Schurian association schemes of the symmetric group

Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Given the symmetric group $G = Sym (n)$ and a multiplicity-free subgroup $H \leq G$ , the orbitals of the action of $G$ on $G / H$ by left multiplication induce a commuta…

math.CO2023

On the intersection spectrum of $PSL_{2} (q)$

Angelot Behajaina, Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Given a group $G$ and a subgroup $H \leq G$ , a set $F \subset G$ is called $H$ \emph{-intersecting} if for any $g, g^{'} \in F$ , there exists $x H \in G / H$ such that $…

math.CO2023

The $q$ -Analogue of Zero Forcing for Certain Families of Graphs

Shaun Fallat, Neha Joshi, Roghayeh Maleki +6

Zero forcing is a combinatorial game played on a graph with the ultimate goal of changing the colour of all the vertices at minimal cost. Originally this game was conceived as a on…

math.CO2023

Infinite families of vertex-transitive graphs with prescribed Hamilton compression

Klavdija Kutnar, Dragan Marušič, Andriaherimanana Sarobidy Razafimahatratra

Given a graph $X$ with a Hamilton cycle $C$ , the {\em compression factor $κ (X, C)$ of $C$ } is the order of the largest cyclic subgroup of $\operatorname{Aut}(C)\cap\operatorname{Aut…

math.CO2022

On closed distance magic circulants of valency up to $5$

Blas Fernández, Roghayeh Maleki, Štefko Miklavič +1

Let $Γ = (V, E)$ be a graph of order $n$ . A {\em closed distance magic labeling} of $Γ$ is a bijection $ℓ : V \to {1, 2, \dots, n}$ for which there exists a positive integer $r$ …

math.CO2022

Intersection density of imprimitive groups of degree $pq$

Angelot Behajaina, Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

A subset $F$ of a finite transitive group $G \leq Sym (Ω)$ is \emph{intersecting} if any two elements of $F$ agree on an element of $Ω$ . The \emph{…

math.CO2022

On the intersection density of the Kneser Graph $K (n, 3)$

Karen Meagher, Andriaherimanana Sarobidy Razafimahatratra

A set $F \subset Sym (V)$ is \textsl{intersecting} if any two of its elements agree on some element of $V$ . Given a finite transitive permutation group $G\l…

math.CO2022

On the intersection density of the symmetric group acting on uniform subsets of small size

Angelot Behajaina, Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Given a finite transitive group $G \leq Sym (Ω)$ , a subset $F$ of $G$ is \emph{intersecting} if any two elements of $F$ agree on some element of $Ω…

math.CO2021

No Hilton-Milner type results for linear groups of degree two

Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

A set of permutations $F$ of a finite transitive permutation group $G \leq Sym (Ω)$ is \emph{intersecting} if any pair of elements of $F$ agree on…

math.CO2021

Erdős-Ko-Rado results for the general linear group, the special linear group and the affine general linear group

Karen Meagher, A. Sarobidy Razafimahatratra

In this paper, we show that both the general linear group $\gl{q}$ and the special linear group $\slg{q}$ have both the EKR property and the EKR-module property. This is done using…

math.CO2021

On non-normal subgroup perfect codes

Angelot Behajaina, Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

Let $X = (V, E)$ be a graph. A subset $C \subseteq V (X)$ is a \emph{perfect code} of $X$ if $C$ is a coclique of $X$ with the property that any vertex in $V (X) ∖ C$ is adjace…

math.CO2021

On the intersection density of primitive groups of degree a product of two odd primes

Andriaherimanana Sarobidy Razafimahatratra

A subset $F$ of a finite transitive group $G \leq Sym (Ω)$ is intersecting if for any $g, h \in F$ there exists $ω \in Ω$ such that $ω^{g} = ω^{h}$ . The \…

math.CO2021

On the second eigenvalue of a Cayley graph of the symmetric group

Roghayeh Maleki, Andriaherimanana Sarobidy Razafimahatratra

In 2020, Siemons and Zalesski [On the second eigenvalue of some Cayley graphs of the symmetric group. {\it arXiv preprint arXiv:2012.12460}, 2020] determined the second eigenvalue…

math.CO2021

On multipartite derangement graphs

Andriaherimanana Sarobidy Razafimahatratra

Given a finite transitive permutation group $G \leq Sym (Ω)$ , with $∣Ω∣ \geq 2$ , the derangement graph $Γ_{G}$ of $G$ is the Cayley graph $\operatorname{Cay}(G,\operatorn…

math.CO2020

$3$ -setwise intersecting families of the symmetric group

Angelot Behajaina, Roghayeh Maleki, Aina Toky Rasoamanana +1

Given two positive integers $n \geq 3$ and $t \leq n$ , the permutations $σ, π \in Sym (n)$ are $t$ -setwise intersecting if they agree (setwise) on a $t$ -subset of $\{1,2,…

math.CO2020★ 1 cited

On triangles in derangement graphs

Andriaherimanana Sarobidy Razafimahatratra, Karen Meagher, Pablo Spiga

Given a permutation group $G$ , the derangement graph $Γ_{G}$ of $G$ is the Cayley graph with connection set the set of all derangements of $G$ . We prove that, when $G$ is transitive…

The automorphism group of the derangement graph of PGL2​(q) acting on the projective line

The intersection densities of transitive actions of PSL2​(q) with cyclic point stabilizers

On the Terwilliger algebras of quasi-thin Schurian association schemes

Perfect and multiple state transfer in oriented Cayley graphs

The intersection density of cubic arc-transitive graphs with 2-arc-regular full automorphism group equal to PGL2​(q)

On the Terwilliger algebra of the group association scheme of the symmetric group sym(7)

On the maximum intersecting sets of the general semilinear group of degree 2

The Erdős-Ko-Rado Theorem for non-quasiprimitive groups of degree 3p

On cocliques in commutative Schurian association schemes of the symmetric group

On the intersection spectrum of PSL2​(q)

The q-Analogue of Zero Forcing for Certain Families of Graphs

Infinite families of vertex-transitive graphs with prescribed Hamilton compression

On closed distance magic circulants of valency up to 5

Intersection density of imprimitive groups of degree pq

On the intersection density of the Kneser Graph K(n,3)

On the intersection density of the symmetric group acting on uniform subsets of small size

No Hilton-Milner type results for linear groups of degree two

Erdős-Ko-Rado results for the general linear group, the special linear group and the affine general linear group

On non-normal subgroup perfect codes

On the intersection density of primitive groups of degree a product of two odd primes

On the second eigenvalue of a Cayley graph of the symmetric group

On multipartite derangement graphs

3-setwise intersecting families of the symmetric group

On triangles in derangement graphs

The automorphism group of the derangement graph of $PGL_{2} (q)$ acting on the projective line

The intersection densities of transitive actions of $PSL_{2} (q)$ with cyclic point stabilizers

The intersection density of cubic arc-transitive graphs with $2$ -arc-regular full automorphism group equal to $PGL_{2} (q)$

On the Terwilliger algebra of the group association scheme of the symmetric group $sym (7)$

On the maximum intersecting sets of the general semilinear group of degree $2$

The Erdős-Ko-Rado Theorem for non-quasiprimitive groups of degree $3 p$

On the intersection spectrum of $PSL_{2} (q)$

The $q$ -Analogue of Zero Forcing for Certain Families of Graphs

On closed distance magic circulants of valency up to $5$

Intersection density of imprimitive groups of degree $pq$

On the intersection density of the Kneser Graph $K (n, 3)$

$3$ -setwise intersecting families of the symmetric group