On contractible curves on normal surfaces
arXiv:math/9911119
Abstract
We characterize contractible curves on proper normal algebraic surfaces in terms of complementary Weil divisors. Using this we generalize the classical criteria of Castelnuovo and Artin. As application we derive a finiteness result on homogeneous spectra defined by Weil divisors on surfaces.
20 pages, submitted to J. Reine Angew. Math