Published online by Cambridge University Press: 18 May 2009
Let A = (aij) be an n × n complex matrix. The permanent of this matrix is
where the sum is taken over all permutations p of the set {1, …, n}.
In a recent paper [1] E. H. Lieb proved an interesting theorem (see below) which he applied to verify some conjectures of M. Marcus and M. Newman. The purpose of this note is to give a simple proof of Lieb's theorem.