MathDB
set finding

Source: Romanian IMO Team Selection Test TST 2002, problem 1

July 4, 2005
inductionnumber theory unsolvednumber theory

Problem Statement

Find all sets AA and BB that satisfy the following conditions: a) AB=ZA \cup B= \mathbb{Z}; b) if xAx \in A then x1Bx-1 \in B; c) if x,yBx,y \in B then x+yAx+y \in A. Laurentiu Panaitopol