On the cone of effective 2-cycles on $\overline{M}_{0,7}$
Algebraic Geometry
2015-09-04 v3
Abstract
Fulton's question about effective -cycles on for can be answered negatively by appropriately lifting to the Keel-Vermeire divisors on . In this paper we focus on the case of -cycles on , and we prove that the -dimensional boundary strata together with the lifts of the Keel-Vermeire divisors are not enough to generate the cone of effective -cycles. We do this by providing examples of effective -cycles on that cannot be written as an effective combination of the aforementioned -cycles. These examples are inspired by a blow up construction of Castravet and Tevelev.
Keywords
Cite
@article{arxiv.1501.01736,
title = {On the cone of effective 2-cycles on $\overline{M}_{0,7}$},
author = {Luca Schaffler},
journal= {arXiv preprint arXiv:1501.01736},
year = {2015}
}
Comments
22 pages, 4 figures. Final version. Minor corrections. To appear in the European Journal of Mathematics