English

Perfect divisibility and 2-divisibility

Combinatorics 2017-04-25 v1

Abstract

A graph GG is said to be 22-divisible if for all (nonempty) induced subgraphs HH of GG, V(H)V(H) can be partitioned into two sets A,BA,B such that ω(A)<ω(H)\omega(A) < \omega(H) and ω(B)<ω(H)\omega(B) < \omega(H). A graph GG is said to be perfectly divisible if for all induced subgraphs HH of GG, V(H)V(H) can be partitioned into two sets A,BA,B such that H[A]H[A] is perfect and ω(B)<ω(H)\omega(B) < \omega(H). We prove that if a graph is (P5,C5)(P_5,C_5)-free, then it is 22-divisible. We also prove that if a graph is bull-free and either odd-hole-free or P5P_5-free, then it is perfectly divisible.

Keywords

Cite

@article{arxiv.1704.06667,
  title  = {Perfect divisibility and 2-divisibility},
  author = {Maria Chudnovsky and Vaidy Sivaraman},
  journal= {arXiv preprint arXiv:1704.06667},
  year   = {2017}
}
R2 v1 2026-06-22T19:24:10.784Z