Generalization of the cover pebbling number on trees

Abstract

A pebbling move on a graph consists of taking two pebbles off from one vertex and add one pebble on an adjacent vertex, the $t$-pebbling number of a graph $G$ is the minimum number of pebbles so that we can move $t$ pebbles on any vertex on $G$ regardless the original distribution of pebbles. Let $\omega$ be a positive function on $V(G)$, the $\omega$-cover pebbling number of a graph $G$ is the minimum number of pebbles so that we can reach a distribution with at least $\omega(v)$ pebbles on $v$ for all $v\in V(G)$. In this paper, we give the $\omega$-cover pebbling number of trees for nonnegative function $\omega$, which generalized the $t$-pebbling number and the traditional weighted cover pebbling number of trees.