如果两个符号图中的一个与另一个的交换同构,则称这两个符号图是交换同构的。轮$W_n$是循环$C_n$和顶点的连接。对于$0 \leq p \leq n$,$ψ_{p}(n)$被定义为在$C_n$上具有恰好$p$负边缘的交换非同构有符号$W_n$的数目。交换非同构带符号$W_n$的数目由$ψ(n)$表示。本文计算了$p=0,1,2,3,4,n-4,n-3,n-2,n-1,n$的$ψ_{p}(n)$值和$n=4,5,...,10$的$ψ(n)$值。我们的方法获得$ψ_{p}(n)$不仅计数开关非同构符号轮,但也产生他们。
英文摘要:
Two signed graphs are called switching isomorphic to each other if one is isomorphic to a switching of the other. The wheel $W_n$ is the join of the cycle $C_n$ and a vertex. For $0 \leq p \leq n$, $ψ_{p}(n)$ is defined to be the number of switching non-isomorphic signed $W_n$ with exactly $p$ negative edges on $C_n$. The number of switching non-isomorphic signed $W_n$ is denoted by $ψ(n)$. In this paper, we compute the values of $ψ_{p}(n)$ for $p=0,1,2,3,4,n-4,n-3,n-2,n-1,n$ and of $ψ(n)$ for $n=4,5,...,10$. Our method of obtaining $ψ_{p}(n)$ not only count the switching non-isomorphic signed wheels but also generates them.
Signed Counting on Restricted Partitions and Combinatorial Proofs of Three Identities
College of Mathematics and Statistics & Center for Discrete Mathematics, Chongqing University(重庆大学数学与统计学院与离散数学中心);College of Mathematics and Statistics, Chongqing University(重庆大学数学与统计学院)
Small Ramsey numbers for books, wheels, and generalizations
Iowa State University(爱荷华州立大学);Center for Communications Research, La Jolla(拉霍亚通信研究中心);University of Colorado Denver(科罗拉多大学丹佛分校);Ghent University(根特大学)