| Popis: |
A vertex-edge perfect Roman dominating function on a graph $ G = (V, E) $ (denoted by ve-PRDF) is a function $ f:V\left(G\right)\longrightarrow\{0, 1, 2\} $ such that for every edge $ uv\in E $, $ \max\{f(u), f(v)\}\neq0 $, or $ u $ is adjacent to exactly one neighbor $ w $ such that $ f(w) = 2 $, or $ v $ is adjacent to exactly one neighbor $ w $ such that $ f(w) = 2 $. The weight of a ve-PRDF on $ G $ is the sum $ w(f) = \sum_{v\in V}f(v) $. The vertex-edge perfect Roman domination number of $ G $ (denoted by $ \gamma_{veR}^{p}(G) $) is the minimum weight of a ve-PRDF on $ G $. In this paper, we first show that vertex-edge perfect Roman dominating is NP-complete for bipartite graphs. Also, for a tree $ T $, we give upper and lower bounds for $ \gamma_{veR}^{p}(T) $ in terms of the order $ n $, $ l $ leaves and $ s $ support vertices. Lastly, we determine $ \gamma_{veR}^{p}(G) $ for Petersen, cycle and Flower snark graphs. |
