Cvm. Vandermee et al., CLASSES OF PLUS MATRICES IN FINITE-DIMENSIONAL INDEFINITE SCALAR PRODUCT-SPACES, Integral equations and operator theory, 30(4), 1998, pp. 432-451
We describe in terms of canonical forms various classes of plus matric
es in real and complex finite dimensional spaces with indefinite scala
r product and study their topological structures (such as closure and
interior).