Z. Taoqiu

activity

20192022

collaborators

5 papers

math.CO2022

Weak-odd chromatic index of special digraph classes

Ruijuan Gu, Hui Lei, Xiaopan Lian +1

Give a digraph $D = (V (D), A (D))$ , let $\partial_{D}^{+} (v) = {v w ∣ w \in N_{D}^{+} (v)}$ and $\partial_{D}^{-} (v) = {uv ∣ u \in N_{D}^{-} (v)}$ be semi-cuts of $v$ . A mapping $φ : A (D) \to [k]$ is call…

math.CO2020

The smallest number of vertices in a 2-arc-strong digraph which has no good pair

Ran Gu, Gregory Gutin, Shasha Li +2

Bang-Jensen, Bessy, Havet and Yeo showed that every digraph of independence number at most 2 and arc-connectivity at least 2 has an out-branching $B^{+}$ and an in-branching $B^{-}$ wh…

math.CO2020

Note on semi-proper orientations of outerplanar graphs

Ruijuan Gu, Gregory Gutin, Yongtang Shi +1

A semi-proper orientation of a given graph $G$ , denoted by $(D, w)$ , is an orientation $D$ with a weight function $w : A (D) \to Z_{+}$ , such that the in-weight of any a…

math.CO2019

A note on rainbow saturation number of paths

Shujuan Cao, Yuede Ma, Zhenyu Taoqiu

For a fixed graph $F$ and an integer $t$ , the \dfn{rainbow saturation number} of $F$ , denoted by $s a t_{t} (n, R (F))$ , is defined as the minimum number of edges in a $t$ -edge…

math.CO2019

Sharp upper bounds on the $k$ -independence number in graphs with given minimum and maximum degree

Zhenyu Taoqiu, Suil O, Yongtang Shi

The $k$ -independence number of a graph $G$ is the maximum size of a set of vertices at pairwise distance greater than $k$ . In this paper, for each positive integer $k$ , we prove sh…