English

The stability of independence polynomials of complete bipartite graphs

Combinatorics 2025-06-02 v1

Abstract

The independence polynomial of a graph is termed {\it stable} if all its roots are located in the left half-plane {zC:Re(z)0}\{z \in \mathbb{C} : \mathrm{Re}(z) \leq 0\}, and the graph itself is also referred to as stable. Brown and Cameron (Electron. J. Combin. 25(1) (2018) \#P1.46) proved that the complete bipartite graph K1,nK_{1,n} is stable and posed the question: \textbf{Are all complete bipartite graphs stable?} We answer this question by establishing the following results: \begin{itemize} \item The complete bipartite graphs K2,nK_{2,n} and K3,nK_{3,n} are stable. \item For any integer k0k\geq0, there exists an integer N(k)NN(k)\in \mathbb{N} such that Km,m+kK_{m,m+k} is stable for all m>N(k)m>N(k). \item For any rational >1\ell> 1, there exists an integer N()NN(\ell) \in \mathbb{N} such that whenever m>N()m >N(\ell) and m\ell \cdot m is an integer, Km,mK_{m, \ell \cdot m} is \textbf{not} stable. \end{itemize}

Keywords

Cite

@article{arxiv.2505.24381,
  title  = {The stability of independence polynomials of complete bipartite graphs},
  author = {Guo Chen and Bo Ning and Jianhua Tu},
  journal= {arXiv preprint arXiv:2505.24381},
  year   = {2025}
}