Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Flag-transitive, point-imprimitive symmetric $2$-$(v,k,\lambda )$
  designs with $k>\lambda \left(\lambda-3 \right)/2$   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 $\mathcal{P}$. Praeger and Zhou \cite{PZ} have shown that, there is a
constant $k_{0}$ such that, for each $B \in \mathcal{B}$ and $\Delta \in
\Sigma$, the size of $\left\vert B \cap \Delta \right \vert$ is either $0$ or
$k_{0}$. In the present paper we show that, if $k>\lambda \left(\lambda-3
\right)/2$ 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 $(96,20,4)$.

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The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph