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arXiv 2203.09261math.CO
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具有$k>λ\left(λ-3 \right)/2$的标志传递点非本原对称$2$设计

Flag-transitive, point-imprimitive symmetric $2$-$(v,k,λ)$ designs with $k>λ\left(λ-3 \right)/2$

Alessandro Montinaro

摘要:

令$\mathcal{D}=\left(\mathcal{P},\mathcal{B} \right)$为对称$2$-$(v,k,λ)$设计,允许标志传递、点非本原自同构群$G$,该群使$\mathcal{P}$的非平凡分区$Σ$保持不变。Praeger和Zhou \cite{PZ}已经表明,存在一个恒定的$k_{0}$,使得对于每个$B \in \mathcal{B}$和$Δ\in Σ$,$\left\vert B \cap Δ\right \vert$的大小是$0$或$k_{0}$。本文证明了,如果$k>λ\left(λ-3 \right)/2$和$k_{0} \geq 3$,则$\mathcal{D}$同构于一个已知的带参数$(45,12,3)$或$(96,20,4)$的标志传递点非本原对称$2$ -设计.

英文摘要:

Let $\mathcal{D}=\left(\mathcal{P},\mathcal{B} \right)$ be a symmetric $2$-$(v,k,λ)$ design admitting a flag-transitive, point-imprimitive automorphism group $G$ that leaves invariant a non-trivial partition $Σ$ of $\mathcal{P}$. Praeger and Zhou \cite{PZ} have shown that, there is a constant $k_{0}$ such that, for each $B \in \mathcal{B}$ and $Δ\in Σ$, the size of $\left\vert B \cap Δ\right \vert$ is either $0$ or $k_{0}$. In the present paper we show that, if $k>λ\left(λ-3 \right)/2$ and $k_{0} \geq 3$, $\mathcal{D}$ is isomorphic to one of the known flag-transitive, point-imprimitive symmetric $2$-designs with parameters $(45,12,3)$ or $(96,20,4)$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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