(1) Department of Mathematics, Faculty of Science, Hokkaido University, 060 Sapporo, Japan;(2) Instituto de Ciências Matemáticas de São Carlos, Universidade de São Paulo, Caixa Postal 668, 13560 São Carlos (SP), Brazil
Abstract:
A formula for the Euler number of a generic singular surface in a 3-manifold is given. We also give an estimate of the number of connected components of the complement of such a surface.