2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/164498Let X be an orbifold with crepant resolution Y. The Crepant Resolution Conjectures of Ruan and Bryan-Graber assert, roughly speaking, that the quantum cohomology of X becomes isomorphic to the quantum cohomology of Y after analytic continuation in certain parameters followed by the specialization of some of these parameters to roots of unity. We prove these conjectures in the case where X is a surface singularity of type A. The key ingredient is mirror symmetry for toric orbifolds.19 pages. v2: references updated; corrected our description of the work of Davesh Maulik. v3: please note that this preprint has been superseded by arXiv:math/0702234v3. The material here, with various typos corrected, appears as Appendix A thereAlgebraic GeometryMathematical Physics14N35 (Primary); 14A20, 53D45 (Secondary)text