English

Total $2$-cut complexes of powers of cycle graphs and Cartesian products of certain graphs

Combinatorics 2025-12-05 v1

Abstract

For a positive integer kk, the \emph{ total kk-cut complex} of a graph GG, denoted as Δkt(G)\Delta_k^t(G), is the simplicial complex whose facets are σV(G)\sigma \subseteq V(G) such that σ=V(G)k|\sigma| = |V(G)|-k and the induced subgraph G[V(G)σ]G[V(G) \setminus \sigma] does not contain any edge. These complexes were introduced by Bayer et al.\ in \cite{Bayer2024TotalCutcomplex} in connection with commutative algebra. In the same paper, they studied the homotopy types of these complexes for various families of graphs, including cycle graphs CnC_n, squared cycle graphs Cn2C_n^2, and Cartesian products of complete graphs and path graphs KmP2K_m \square P_2 and K2PnK_2 \square P_n. In this article, we extend the work of Bayer et al.\ for these families of graphs. We focus on the complexes Δ2t(G)\Delta_2^t(G) and determine the homotopy types of these complexes for three classes of graphs: (i) pp-th powers of cycle graphs CnpC_n^p (ii) KmPnK_m \square P_n and (iii) KmCnK_m \square C_n. Using discrete Morse theory, we show that these complexes are homotopy equivalent to wedges of spheres. We also give the number and dimension of spheres appearing in the homotopy type. Our result on powers of cycle graphs CnpC_n^p proves a conjecture of Shen et al.\ about the homotopy type of the complexes Δ2t(Cnp)\Delta_2^t(C_n^p).

Keywords

Cite

@article{arxiv.2512.04486,
  title  = {Total $2$-cut complexes of powers of cycle graphs and Cartesian products of certain graphs},
  author = {Pratiksha Chauhan and Samir Shukla and Kumar Vinayak},
  journal= {arXiv preprint arXiv:2512.04486},
  year   = {2025}
}

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16 pages