Compactifications of Hurwitz spaces
arXiv:1206.4535
Abstract
We construct several modular compactifications of the Hurwitz space of genus curves expressed as -sheeted, simply branched covers of genus curves. These compactifications are obtained by allowing the branch points of the covers to collide to a variable extent. They are very well-behaved if , or if relatively few collisions are allowed. We recover as special cases the spaces of twisted admissible covers of Abramovich, Corti and Vistoli and the spaces of hyperelliptic curves of Fedorchuk.