English

On a series of Gorenstein cyclic quotient singularities admitting a unique projective crepant resolution

Algebraic Geometry 2007-05-23 v1

Abstract

In this paper we prove that the Gorenstein cyclic quotient singularities of type \frac 1l (1,..., 1,l-(r-1)) with lr2l\geq r\geq 2, have a \textit{unique}torus-equivariant projective, crepant, partial resolution, which is ``full'' iff either l0l\equiv 0 mod % (r-1) or l1l\equiv 1 mod (r1)(r-1) . As it turns out, if one of these two conditions is fulfilled, then the exceptional locus of the full desingularization consists of lr1\lfloor \frac{l}{r-1} \rfloor prime divisors, lr11\lfloor \frac{l}{r-1}\rfloor - 1 of which are isomorphic to the total spaces of PC1\Bbb{P}_{\Bbb{C}}^1-bundles over \Bbb{P}_{\Bbb{C}%}^{r-2}. Moreover, it is shown that intersection numbers are computable explicitly and that the resolution morphism can be viewed as a composite of successive (normalized) blow-ups. Obviously, the monoparametrized singularity-series of the above type contains (as its ``first member'') the well-known Gorenstein singularity defined by the origin of the affine cone which lies over the rr-tuple Veronese embedding of PCr1\Bbb{P}_{\Bbb{C}}^{r-1}.

Keywords

Cite

@article{arxiv.math/9803094,
  title  = {On a series of Gorenstein cyclic quotient singularities admitting a unique projective crepant resolution},
  author = {Dimitrios I. Dais and Martin Henk},
  journal= {arXiv preprint arXiv:math/9803094},
  year   = {2007}
}

Comments

96 pages. 14 Figures. LaTeX 2e with AMS and epsfig macros. This is the revised version of the ZIB preprint SC-97-39. To appear in the DMV-Seminar-Volume "Combinatorial Convex Geometry and Toric Varieties", Birkhaeuser. (For correct placement of figures we would recommend the use of the LaTeX sources instead of the direct PostScript link)