MathDB

Square matrices A and B

Source: Putnam 1990 A5

July 12, 2013

Putnamcollege contests

Problem Statement

\mathbf{A}

and

\mathbf{B}

are square matrices of the same size such that

\mathbf{ABAB}=\mathbf{0}

, does it follow that

\mathbf{BABA}=\mathbf{0}