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Computer Science, Discrete Mathematics, cs.DM
Abstract:
Suppose you are given a graph $G=(V,E)$ with a weight assignment
$w:V\rightarrow\mathbb{Z}$ and that your objective is to modify $w$ using legal
steps such that all vertices will have the same weight, where in each legal
step you are allowed to choose an edge and increment the weights of its end
points by $1$.
In this paper we study several variants of this problem for graphs and
hypergraphs. On the combinatorial side we show connections with fundamental
results from matching theory such as Hall's Theorem and Tutte's Theorem. On the
algorithmic side we study the computational complexity of associated decision
problems.
Our main results are a characterization of the graphs for which any initial
assignment can be balanced by edge-increments and a strongly polynomial-time
algorithm that computes a balancing sequence of increments if one exists.