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arXiv 2203.14217math.CO
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有限交换环的零因子图作为阈值图的实现

Realization of zero-divisor graphs of finite commutative rings as threshold graphs

Rameez Raja, Samir Ahmad Wagay

摘要:

设R是一个有单位元的有限交换环,G =(V,E)是一个简单图.零因子图,记为Γ(R),是一个顶点集为R的简单图,两个顶点x,y \in R在Γ(R)中相邻当且仅当$xy = 0$ .在[10]中,作者研究了图Γ(Z_n)的Laplacian特征值,对于n的不同真因子d_1,d_2,\dots,d_k,定义了如下集合:A_{d_i} = {x \in Zn:(x,n)= d_i},其中(x,n)表示x和n的最大公因数。本文证明了集合A_{d_i},1 \leq i \leq k实际上是群作用的轨道:Aut(Γ(R))\times R \longrightarrow R,其中Aut(Γ(R))表示Γ(R)的自同构群.我们的主要目标是确定新的阈值图类,因为这些图在几个应用领域中发挥着重要作用。对于约化环R,我们证明了Γ(R)是连通阈值图当且仅当R = F_q或R = F_2 \times F_q.我们提供了几类局部环实现的阈值图。最后,我们刻画了所有零因子图不是阈值的具有单位元的有限交换环。

英文摘要:

Let R be a finite commutative ring with unity, and let G = (V, E) be a simple graph. The zero-divisor graph, denoted by Γ(R) is a simple graph with vertex set as R, and two vertices x, y \in R are adjacent in Γ(R) if and only if $xy = 0$. In [10], the authors have studied the Laplacian eigenvalues of the graph Γ(Z_n) and for distinct proper divisors d_1, d_2, \dots, d_k of n, they defined the sets as, A_{d_i} = {x \in Zn : (x, n) = d_i}, where (x, n) denotes the greatest common divisor of x and n. In this paper, we show that the sets A_{d_i}, 1 \leq i \leq k are actually orbits of the group action: Aut(Γ(R)) \times R \longrightarrow R, where Aut(Γ(R)) denotes the automorphism group of Γ(R). Our main objective is to determine new classes of threshold graphs, since these graphs play an important role in several applied areas. For a reduced ring R, we prove that Γ(R) is a connected threshold graph if and only if R = F_q or R = F_2 \times F_q. We provide classes of threshold graphs realized by some classes of local rings. Finally, we characterize all finite commutative rings with unity of which zero-divisor graphs are not threshold.

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