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In this article, we study flag-transitive automorphism groups of non-trivial symmetric $(v, k, \lambda)$ designs, where $\lambda$ divides $k$ and $k\geq \lambda^2$. We show that such an automorphism group is either point-primitive of affine…

Group Theory · Mathematics 2019-01-15 Seyed Hassan Alavi , Ashraf Daneshkhah , Narges Okhovat

In this article, we study $2$-designs with $\gcd(r,\lambda)=1$ admitting a flag-transitive almost simple automorphism group with socle a finite simple exceptional group of Lie type. We obtain four infinite families of such designs and…

Group Theory · Mathematics 2020-04-06 Seyed Hassan Alavi

The classification of the $2$-designs with $\lambda=2$ admitting a flag-transitive automorphism groups with socle $PSL(2,q)$ is completed by settling the two open cases in \cite{ABDT}. The result is achieved by using conics and hyperovals…

Combinatorics · Mathematics 2024-05-01 Alessandro Montinaro , Yanwei Zhao , Zhilin Zhang , Shenglin Zhou

In this paper, we completely classify the non-trivial 2-(v,k,3) designs admitting an almost simple, flag-transitive automorphism group with socle PSL(2,q).

Combinatorics · Mathematics 2025-12-25 Hongxue Liang , Zhihui Liu , Alessandro Montinaro

This paper determined all pairs $(\mathcal{D},G)$ where $\mathcal{D}$ is a non-symmetric 2-$(v,k,\lambda)$ design with $(r,\lambda)=1$ and $G$ is the almost simple flag-transitive automorphism group of $\mathcal{D}$ with an exceptional…

Combinatorics · Mathematics 2019-07-16 Yongli Zhang , Shenglin Zhou

In this article, we investigate symmetric designs admitting a flag-transitive and point-primitive affine automorphism group. We prove that if an automorphism group $G$ of a symmetric $(v,k,\lambda)$ design with $\lambda$ prime is…

Group Theory · Mathematics 2024-10-15 Seyed Hassan Alavi , Mohsen Bayat , Ashraf Daneshkhah , Alessandro Montinaro

In this article, we study $2$-designs with prime replication number admitting a flag-transitive automorphism group. The automorphism groups of these designs are point-primitive of almost simple or affine type. We determine $2$-designs with…

Group Theory · Mathematics 2019-08-16 Seyed Hassan Alavi , Mohsen Bayat , Jalal Choulaki , Asharf Daneshkhah

In this article, we study $2$-$(v,k,\lambda)$ designs $\mathcal{D}$ with $\lambda$ prime admitting flag-transitive and point-primitive almost simple automorphism groups $G$ with socle $T$ a finite exceptional simple group or a sporadic…

Group Theory · Mathematics 2025-05-09 Seyed Hassan Alavi , Ashraf Daneshkhah , Alessandro Montinaro

Let $\mathcal{D}=\left(\mathcal{P},\mathcal{B} \right)$ be a symmetric $2$-$(v,k,\lambda )$ design admitting a flag-transitive, point-imprimitive automorphism group $G$ that leaves invariant a non-trivial partition $\Sigma$ of…

Combinatorics · Mathematics 2022-06-15 Alessandro Montinaro

Non-trivial $2$-$(k^{2},k,\lambda )$ designs, with $\lambda \mid k$, admitting a flag-transitive almost simple automorphism group are classified.

Group Theory · Mathematics 2022-03-18 Alessandro Montinaro

Let $\mathcal{D}$ be a nontrivial $3$-$(v,k,1)$ design admitting a block-transitive group $G$ of automorphisms. A recent work of Gan and the second author asserts that $G$ is either affine or almost simple. In this paper, it is proved that…

Group Theory · Mathematics 2023-05-17 Ting Lan , Weijun Liu , Fu-Gang Yin

The Kramer-Mesner method for constructing designs with a prescribed automorphism group $G$ has proven effective many times. In the special case of Steiner designs, the task reduces to solving an exact cover problem, with the advantage that…

This paper deals with block-transitive $t$-$(v,k,\lambda)$ designs in affine spaces for large $t$, with a focus on the important index $\lambda=1$ case. We prove that there are no non-trivial 5-$(v,k,1)$ designs admitting a block-transitive…

Combinatorics · Mathematics 2018-07-03 Michael Huber

In this article, we study symmetric designs admitting flag-transitive, point-imprimitive almost simple automorphism groups with socle sporadic simple groups. As a corollary, we present a classification of symmetric designs admitting…

Group Theory · Mathematics 2023-07-12 Seyed Hassan Alavi , Ashraf Daneshkhah

This paper studies the long-standing open problem of the reduction of Steiner 3-designs admitting a block-transitive automorphism group. We prove that if G acts as a point-primitive, block-transitive automorphism group of a nontrivial…

Combinatorics · Mathematics 2024-08-28 Yunsong Gan , Weijun Liu

This paper studies flag-transitive point-primitive non-symmetric $2$-($v,k,2$) designs. We prove that if $\mathcal{D}$ is a non-trivial non-symmetric $2$-$(v,k,2)$ design admitting a flag-transitive point-primitive automorphism group $G$…

Combinatorics · Mathematics 2016-03-03 Hongxue Liang , Shenglin Zhou

Coding theory and combinatorial $t$-designs have close connections and interesting interplay. One of the major approaches to the construction of combinatorial t-designs is the employment of error-correcting codes. As we all known, some…

Information Theory · Computer Science 2021-10-11 Can Xiang , Chunming Tang , Qi Liu

This paper considers flag-transitive $4$-$(q+1,k,\lambda)$ designs with $\lambda\geq5$ and $q+1>k>4$. Let the automorphism group of a design $\cal D$ be a simple group $G=PSL(2,q)$. Depend on the fact that the setwise stabilizer $G_B$ must…

Combinatorics · Mathematics 2019-10-24 Huili Dong

A $3$-$(v,\{4,6\},1)$ design is a configuration of $v$ points and a collection of $4$- and $6$-element subsets called blocks, that jointly contain every 3-element subset exactly once. Using an exhaustive computer search on $v\leq 28$ points…

Combinatorics · Mathematics 2023-05-09 M. Epstein , D. L. Kreher , S. S. Magliveras

In this article, we study symmetric $(v, k, \lambda)$ designs admitting a flag-transitive and point-primitive automorphism group $G$ whose socle is a projective special unitary group of dimension at most five. We, in particular, determine…

Group Theory · Mathematics 2019-12-04 Ashraf Daneshkhah