MathDB
Graph

Source: Iran TST 2004

August 10, 2006
combinatorics proposedcombinatorics

Problem Statement

This problem is generalization of [url=http://www.mathlinks.ro/Forum/viewtopic.php?t=5918]this one. Suppose GG is a graph and SV(G)S\subset V(G). Suppose we have arbitrarily assign real numbers to each element of SS. Prove that we can assign numbers to each vertex in G\SG\backslash S that for each vG\Sv\in G\backslash S number assigned to vv is average of its neighbors.