An Introduction to Virtual Cycles—Via Classical Algebraic Geometry
摘要
One way of counting geometric objects is to construct a virtual cycle of the moduli space parametrising those objects. Then a virtual counting is obtained by an integration over the cycle. In this manuscript, we review the construction of virtual cycles of Li-Tian [LT] and Behrend-Fantechi [BF]. Then we introduce various useful methods for their study.