Carmen Amarra

activity

20162026

most citedThe girth, odd girth, distance function, and diameter of generalized Johnson graphs

21 citations · 22 across the 9 of their papers we have counts for

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10 papers · 1 filter

math.CO2026

Recursive constructions for block-transitive, poset-imprimitive two-designs

Carmen Amarra, Alice Devillers, Cheryl E. Praeger

We give two general constructions for $2$ -designs, that can be used recursively, and interchangeably, to produce new infinite families of $2$ -designs admitting block-transitive gro…

math.CO2024

Higher-dimensional grid-imprimitive block-transitive designs

Seyed Hassan Alavi, Carmen Amarra, Ashraf Daneshkhah +2

It was shown in 1989 by Delandtsheer and Doyen that, for a $2$ -design with $v$ points and block size $k$ , a block-transitive group of automorphisms can be point-imprimitive (that i…

math.CO2024

Chain-imprimitive, flag-transitive 2-designs

Carmen Amarra, Alice Devillers, Cheryl E. Praeger

We consider $2$ -designs which admit a group of automorphisms that is flag-transitive and leaves invariant a chain of nontrivial point-partitions. We build on our recent work on $2$ …

math.CO2023★ 21 cited

The girth, odd girth, distance function, and diameter of generalized Johnson graphs

John S. Caughman, Ari J. Herman, Taiyo S. Terada

For any non-negative integers $v > k > i$ , the {\em generalized Johnson graph}, $J (v, k, i)$ , is the undirected simple graph whose vertices are the $k$ -subsets of a $v$ -set, and wher…

math.CO2023

Block-transitive 2-designs with a chain of imprimitive partitions

Carmen Amarra, Alice Devillers, Cheryl E. Praeger

More than $30$ years ago, Delandtsheer and Doyen showed that the automorphism group of a block-transitive $2$ -design, with blocks of size $k$ , could leave invariant a nontrivial po…

math.CO2021

Multiple contractions of permutation arrays

Carmen Amarra, Dom Vito A. Briones, Manuel Joseph C. Loquias

Given a permutation $σ$ on $n$ symbols ${0, 1, \dots, n - 1}$ and an integer $1 \leq m \leq n - 1$ , the $m$ th contraction of $σ$ is the permutation $σ^{CT^{m}}$ on $n - m$ symbols…

math.CO2020

Delandtsheer--Doyen parameters for block-transitive point-imprimitive 2-designs

Carmen Amarra, Alice Devillers, Cheryl E. Praeger

Delandtsheer and Doyen bounded, in terms of the block size, the number of points of a point-imprimitive, block-transitive 2-design. To do this they introduced two integer parameter…

math.CO2019★ 1 cited

On locally $n \times n$ grid graphs

Carmen Amarra, Wei Jin, Cheryl E. Praeger

We investigate locally $n \times n$ grid graphs, that is, graphs in which the neighbourhood of any vertex is the Cartesian product of two complete graphs on $n$ vertices. We consid…

math.CO2017

Quotient-complete arc-transitive latin square graphs from groups

Carmen Amarra

We consider latin square graphs $Γ = LSG (H)$ of the Cayley table of a given finite group $H$ . We characterize all pairs $(Γ, G)$ , where $G$ is a subgroup of autoparatopisms of t…

math.CO2016

Affine primitive symmetric graphs of diameter two

Carmen Amarra, Michael Giudici, Cheryl E. Praeger

Let $n$ be a positive integer, $q$ be a prime power, and $V$ be a vector space of dimension $n$ over $F_{q}$ . Let $G := V ⋊ G_{0}$ , where $G_{0}$ is an irreducible subgrou…

Recursive constructions for block-transitive, poset-imprimitive two-designs

Higher-dimensional grid-imprimitive block-transitive designs

Chain-imprimitive, flag-transitive 2-designs

The girth, odd girth, distance function, and diameter of generalized Johnson graphs

Block-transitive 2-designs with a chain of imprimitive partitions

Multiple contractions of permutation arrays

Delandtsheer--Doyen parameters for block-transitive point-imprimitive 2-designs

On locally n×n grid graphs

Quotient-complete arc-transitive latin square graphs from groups

Affine primitive symmetric graphs of diameter two

On locally $n \times n$ grid graphs