Semi-free Zp-Actions on Highly-Connected Manifolds.
Four-Manifolds Constructed via Plumbing.
Invariants of branched covering from the work of Serre and Mumford.
Bielliptic Abelian Surfaces.
The principal degenerations of abelian surfaces and their polarisations.
Cohomology of the boundary of Siegel modular varieties of degree two, with applications
Let 𝓐₂(n) = Γ₂(n)∖𝔖₂ be the quotient of Siegel's space of degree 2 by the principal congruence subgroup of level n in Sp(4,ℤ). This is the moduli space of principally polarized abelian surfaces with a level n structure. Let 𝓐₂(n)* denote the Igusa compactification of this space, and ∂𝓐₂(n)* = 𝓐₂(n)* - 𝓐₂(n) its "boundary". This is a divisor with normal crossings. The main result of this paper is the determination of H(∂𝓐₂(n)*) as a module over the finite group Γ₂(1)/Γ₂(n). As an application...
Singularities of the moduli spaces of certain abelian surfaces
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