On certain reduction problems concerning Abelian surfaces.
On special values of theta functions of genus two
We study a certain finitely generated multiplicative subgroup of the Hilbert class field of a quartic CM field. It consists of special values of certain theta functions of genus 2 and is analogous to the group of Siegel units. Questions of integrality of these specials values are related to the arithmetic of the Siegel moduli space.
Class Invariants for Quartic CM Fields
One can define class invariants for a quartic primitive CM field as special values of certain Siegel (or Hilbert) modular functions at CM points corresponding to . Such constructions were given by de Shalit-Goren and Lauter. We provide explicit bounds on the primes appearing in the denominators of these algebraic numbers. This allows us, in particular, to construct -units in certain abelian extensions of a reflex field of , where is effectively determined by , and to bound the primes appearing...
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