Dergiler / Turkish Journal of Mathematics / 2014 / Cilt: 38 - Sayı: 4
On Kapranov's description of \overline{M}0,n as a Chow quotient
- Sayfa
- 625–648
- DOI
- —
Özet
We provide a direct proof, valid in arbitrary characteristic, of the result originally proven by Kapranov over C that the Hilbert quotient (P1)n//HPGL2 and Chow quotient (P1)n//ChPGL2 are isomorphic to \overline{M}0,n. In both cases this is done by explicitly constructing the universal family of orbit closures and then showing that the induced morphism is an isomorphism onto its image. The proofs of these results in many ways reduce to the case n = 4; in an appendix we outline a formalism of this phenomenon relating to certain operads.
Abstract
We provide a direct proof, valid in arbitrary characteristic, of the result originally proven by Kapranov over C that the Hilbert quotient (P1)n//HPGL2 and Chow quotient (P1)n//ChPGL2 are isomorphic to \overline{M}0,n. In both cases this is done by explicitly constructing the universal family of orbit closures and then showing that the induced morphism is an isomorphism onto its image. The proofs of these results in many ways reduce to the case n = 4; in an appendix we outline a formalism of this phenomenon relating to certain operads.