MathDB
Balanced set

Source: Indian TST Day 1 problem 3.

July 2, 2011
combinatorics unsolvedcombinatorics

Problem Statement

A set of nn distinct integer weights w1,w2,,wnw_1,w_2,\ldots, w_n is said to be balanced if after removing any one of weights, the remaining (n1)(n-1) weights can be split into two subcollections (not necessarily with equal size)with equal sum.
a)a) Prove that if there exist balanced sets of sizes k,jk,j then also a balanced set of size k+j1k+j-1. b)b) Prove that for all odd n7n\geq 7 there exist a balanced set of size nn.