English

Some criteria for integer sequences pair being realizable by a graph

Combinatorics 2022-09-15 v1

Abstract

Let A=(a1,,an)A=(a_1,\ldots,a_n) and B=(b1,,bn)B=(b_1,\ldots,b_n) be two sequences of nonnegative integers with aibia_i \le b_i for 1in1\le i\le n. The pair (A;B)(A;B) is said to be realizable by a graph if there exists a simple graph GG with vertices v1,,vnv_1,\ldots, v_n such that aidG(vi)bia_i\le d_G(v_i)\le b_i for 1in1\le i\le n. Let \preceq denote the lexicographic ordering on Z×Z:Z\times Z: (ai+1,bi+1)(ai,bi)[(ai+1<ai)((ai+1=ai)&(bi+1bi))](a_{i+1},b_{i+1})\preceq (a_i,b_i)\Longleftrightarrow [(a_{i+1}<a_i)\vee ((a_{i+1}=a_i)\&(b_{i+1}\le b_i))]. We say that the sequences AA and BB are in good order if (ai+1,bi+1)(ai,bi)(a_{i+1},b_{i+1})\preceq (a_i,b_i). In this paper, we consider the generalizations of six classical characterizations on sequences pair due to Berge, Ryser et al. and present related results.

Keywords

Cite

@article{arxiv.2209.06379,
  title  = {Some criteria for integer sequences pair being realizable by a graph},
  author = {Jiyun Guo and Miao Fu and Jun Wang},
  journal= {arXiv preprint arXiv:2209.06379},
  year   = {2022}
}
R2 v1 2026-06-28T01:15:21.972Z