Proof of a conjectured exponential formula
Robert C. Thompson · Linear and Multilinear Algebra · 1986
A proof is outlined for the conjecture that, if A and B are Hermitian matrices, unitary matrices U and V exist such that . The proof uses results announced by B. V. Lidskii for the eigenvalues of a sum of Hermitian matrices, a theorem of A. Nudel'man and P. Svarcman on the eigenvalues of a product of unitary matrices, and certain facts from perturbation theory.