English

Realizing degree sequences as $Z_3$-connected graphs

Combinatorics 2014-07-15 v1

Abstract

An integer-valued sequence π=(d1,,dn)\pi=(d_1, \ldots, d_n) is {\em graphic} if there is a simple graph GG with degree sequence of π\pi. We say the π\pi has a realization GG. Let Z3Z_3 be a cyclic group of order three. A graph GG is {\em Z3Z_3-connected} if for every mapping b:V(G)Z3b:V(G)\to Z_3 such that vV(G)b(v)=0\sum_{v\in V(G)}b(v)=0, there is an orientation of GG and a mapping f:E(G)Z3{0}f: E(G)\to Z_3-\{0\} such that for each vertex vV(G)v\in V(G), the sum of the values of ff on all the edges leaving from vv minus the sum of the values of ff on the all edges coming to vv is equal to b(v)b(v). If an integer-valued sequence π\pi has a realization GG which is Z3Z_3-connected, then π\pi has a {\em Z3Z_3-connected realization} GG. Let π=(d1,,dn)\pi=(d_1, \ldots, d_n) be a graphic sequence with d1dn3d_1\ge \ldots \ge d_n\ge 3. We prove in this paper that if d1n3d_1\ge n-3, then either π\pi has a Z3Z_3-connected realization unless the sequence is (n3,3n1)(n-3, 3^{n-1}) or is (k,3k)(k, 3^k) or (k2,3k1)(k^2, 3^{k-1}) where k=n1k=n-1 and nn is even; if dn54d_{n-5}\ge 4, then either π\pi has a Z3Z_3-connected realization unless the sequence is (52,34)(5^2, 3^4) or (5,35)(5, 3^5).

Keywords

Cite

@article{arxiv.1407.3531,
  title  = {Realizing degree sequences as $Z_3$-connected graphs},
  author = {Fan Yang and Xiangwen Li and Hong -Jian Lai},
  journal= {arXiv preprint arXiv:1407.3531},
  year   = {2014}
}
R2 v1 2026-06-22T05:03:04.607Z