2 papers
math.AG2026
Tautological modular forms of level two and degree two
Fabien Cléry, Gerard van der Geer
We show how to use divisors on the projectivized Hodge bundle to construct special vector-valued modular forms and then apply invariant theory to construct all vector-valued Siegel…
math.AG2025
On the number of real forms of a complex variety
Gerard van der Geer, Xun Yu
We give a bound on the number of weighted real forms of a complex variety with finite automorphism group, where the weight is the inverse of the number of automorphisms of the real…