English

Partition of a Subset into Two Directed Cycles with Partial Degrees

Combinatorics 2019-07-29 v1

Abstract

Let D=(V,A)D=(V,A) be a directed graph of order n6n\geq 6. Let WW be a subset of VV with W6|W|\geq 6. Suppose that every vertex of WW has degree at least (3n3)/2(3n-3)/2 in DD. Then for any integer partition W=n1+n2|W|=n_1+n_2 with n13n_1\geq 3 and n23n_2\geq 3, DD contains two disjoint directed cycles C1C_1 and C2C_2 such that V(C1)W=n1|V(C_1)\cap W|=n_1 and V(C2)W=n2|V(C_2)\cap W|=n_2. We conjecture that for any integer partition W=n1+n2++nk|W|=n_1+n_2+\cdots +n_k with k3k\geq 3 and ni3(1ik)n_i\geq 3(1\leq i\leq k), DD contains kk disjoint directed cycles C1,C2,,CkC_1,C_2,\ldots , C_k such that V(Ci)W=ni|V(C_i)\cap W|=n_i for all 1ik1\leq i\leq k. The degree condition is sharp in general.

Keywords

Cite

@article{arxiv.1907.11668,
  title  = {Partition of a Subset into Two Directed Cycles with Partial Degrees},
  author = {Hong Wang},
  journal= {arXiv preprint arXiv:1907.11668},
  year   = {2019}
}
R2 v1 2026-06-23T10:32:11.480Z