English

Deranged Perfect Matchings on complete graph and balanced complete r-partite graph

Combinatorics 2026-03-24 v3

Abstract

We proved that for any finite collection of sparse subgraphs (Dm)m=1(D_m)_{m=1}^\ell of the complete graph K2nK_{2n}, and a uniformly chosen perfect matching RR in K2nK_{2n}, the random vector (E(RDm))m=1(|E(R \cap D_m)|)_{m=1}^\ell jointly converges to a vector of independent Poisson random variables with mean E(Dm)/(2n)|E(D_m)|/(2n). We also showed a similar result when K2nK_{2n} is replaced by the balanced complete rr-partite graph Kr×2n/rK_{r \times 2n/r} for fixed rr and determined the asymptotic joint distribution. The proofs rely on elementary tools of the Principle of Inclusion-Exclusion and generating functions. These results extend recent works of Johnston, Kayll and Palmer, Spiro and Surya, and Granet and Joos from the univariate to the multivariate setting.

Keywords

Cite

@article{arxiv.2505.13799,
  title  = {Deranged Perfect Matchings on complete graph and balanced complete r-partite graph},
  author = {Boqing Deng},
  journal= {arXiv preprint arXiv:2505.13799},
  year   = {2026}
}
R2 v1 2026-07-01T02:23:39.453Z