On the multiplicities of eigenvalues of a Hermitian matrix whose graph is a tree
A different approach is given to recent results due mainly to R.C. Johnson and A. Leal Duarte on the multiplicities of eigenvalues of a Hermitian matrix whose graph is a tree. The technics developed are based on some results of matchings polynomials and use a work by O.L. Heilmann and E.H. Lieb on an apparently unrelated topic.
Pré-publicações do Departamento de Matemática da Universidade de Coimbra