3 papers
math.AG2008
Abelianisation of orthogonal groups and the fundamental group of modular varieties
V. Gritsenko, K. Hulek, G. K. Sankaran
We study the commutator subgroup of integral orthogonal groups belonging to indefinite quadratic forms. We show that the index of this commutator is 2 for many groups that occur in…
math.AG2008
The moduli space of étale double covers of genus 5 curves is unirational
E. Izadi, M. Lo Giudice, G. K. Sankaran
We show that the coarse moduli space $\cR_5$ of étale double covers of curves of genus~5 over the complex numbers is unirational. We give two slightly different arguments, one pure…
math.AG2007
Numerical obstructions to abelian surfaces in toric Fano 4-folds
G. K. Sankaran
Some of the 124 toric Fano 4-folds contain abelian surfaces but most do not: in a few cases it is not known whether they do or not. By elementary methods, with a little computer he…