English

Subgraphs in random graphs with specified degrees and forbidden edges

Combinatorics 2025-10-29 v1

Abstract

Let GG be a uniformly chosen simple (labelled) random graph with given degree sequence d\boldsymbol{d} and let X,Y,LX,Y,L be edge-disjoint graphs on the same vertex set as GG. We investigate the probability that XGX \subseteq G and that GY=G \cap Y = \emptyset both conditioned on the event GL=G \cap L = \emptyset. We improve upon known bounds of these probabilities and extend them to a wider range of degree sequences through a more precise edge switching argument. Notably, a few vertices of linear degree are permitted provided that the subgraph XX does not have an edge incident with them. Further, the graph LL is permitted to contain many edges (we provide an example where LL is a spanning rr-regular subgraph with r=o(n)r = o(n)). We provide the same analysis when GG is a simple (labelled) bipartite random graph with a given degree sequence (s,t)(\boldsymbol{s},\boldsymbol{t}). Our work extends the results of Gao and Ohapkin (2023) and McKay (1981, 2010).

Keywords

Cite

@article{arxiv.2510.24276,
  title  = {Subgraphs in random graphs with specified degrees and forbidden edges},
  author = {John Larkin and Brendan D. McKay and Fang Tian},
  journal= {arXiv preprint arXiv:2510.24276},
  year   = {2025}
}
R2 v1 2026-07-01T07:09:21.567Z