Modular Interpretation Of A Non-Reductive Chow Quotient
Proceedings Of The Edinburgh Mathematical Society
The space of n distinct points and adisjoint parametrized hyperplane in projective d-space up to projectivity – equivalently, configurations of n distinct points in affine d-space up to translation and homothety – has a beautiful compactification introduced by Chen, Gibney and Krashen. This variety, constructed inductively using the apparatus of Fulton–MacPherson configuration spaces, is a parameter space of certain pointed rational varieties whose dual intersection complex is a rooted tree. This generalizes and shares many properties with it. In this paper, we prove that the normalization of the Chow quotient of (ℙd)n by the diagonal action of the subgroup of projectivities fixing a hyperplane, pointwise, is isomorphic to this Chen–Gibney–Krashen space Td, n. This is a non-reductive analogue of Kapranov's famous quotient construction of , and indeed as a special case we show that is the Chow quotient of (ℙ1)n−1 by an action of �m ⋊ �a.
Chow quotient, stable trees, non-reductive
P. Gallardo and Noah Giansiracusa.
"Modular Interpretation Of A Non-Reductive Chow Quotient".
Proceedings Of The Edinburgh Mathematical Society.