MathDB
A has property P iff A is a field

Source: Romanian MO 2010 Grade 12

August 6, 2012
algebrapolynomialRing Theorysuperior algebrasuperior algebra unsolved

Problem Statement

We say that a ring AA has property (P)(P) if any non-zero element can be written uniquely as the sum of an invertible element and a non-invertible element. a) If in AA, 1+1=01+1=0, prove that AA has property (P)(P) if and only if AA is a field. b) Give an example of a ring that is not a field, containing at least two elements, and having property (P)(P).
Dan Schwarz