Quivers, long exact sequences and Horn type inequalities II

Abstract

We study the set of all m-tuples $(\lambda (1),...,\lambda (m))$ of possible types of finite abelian p-groups $M_{\lambda (1)},...,M_{\lambda (m)}$ for which there exists a long exact sequence $M_{\lambda (1)}\to ...\to M_{\lambda (m)}$. When m=3, we recover Fulton's results on the possible eigenvalues of majorized Hermitian matrices.