5 citations · 11 across the 9 of their papers we have counts for
10 papers
A framework for Tate modules of abelian varieties under isogeny
Sarah Frei, Katrina Honigs, John Voight
We explain the linear algebraic framework provided by Tate modules of isogenous abelian varieties in a category-theoretic way.
Conic bundle threefolds differing by a constant Brauer class and connections to rationality
Sarah Frei, Lena Ji, Soumya Sankar +2
A double cover of ramified over a general -divisor will have the structure of a geometrically standard conic bundle ramified over a sm…
On abelian varieties whose torsion is not self-dual
Sarah Frei, Katrina Honigs, John Voight
We construct infinitely many abelian surfaces A defined over the rational numbers such that, for a prime ell <= 7, the ell-torsion subgroup of A is not isomorphic as a Galois modul…
A threefold violating a local-to-global principle for rationality
Sarah Frei, Lena Ji
In this note we construct an example of a smooth projective threefold that is irrational over but is rational at all places. Our example is a complete intersection of t…
Groups of symplectic involutions on symplectic varieties of Kummer type and their fixed loci
Sarah Frei, Katrina Honigs
We describe the Galois action on the middle -adic cohomology of smooth, projective fourfolds that occur as a fiber of the Albanese morphism on moduli spaces of sheav…
Curve classes on conic bundle threefolds and applications to rationality
Sarah Frei, Lena Ji, Soumya Sankar +2
We undertake a study of conic bundle threefolds over geometrically rational surfaces whose associated discriminant covers are smooth and geo…
Reduction of Brauer classes on K3 surfaces, rationality and derived equivalence
Sarah Frei, Brendan Hassett, Anthony Várilly-Alvarado
We consider the reduction of Brauer classes on surfaces over number fields, with a view toward applications to rationality and derived equivalence. We show that a Brauer class on a…
Rational points and derived equivalence
Nicolas Addington, Benjamin Antieau, Sarah Frei +1
We give the first examples of derived equivalences between varieties defined over non-closed fields where one has a rational point and the other does not. We begin with torsors ove…
Moduli spaces of sheaves on K3 surfaces and Galois representations
Sarah Frei
We consider two K3 surfaces defined over an arbitrary field, together with a smooth proper moduli space of stable sheaves on each. When the moduli spaces have the same dimension, w…
The a-number of hyperelliptic curves
Sarah Frei
It is known that for a smooth hyperelliptic curve to have a large -number, the genus must be small relative to the characteristic of the field, , over which the curve is de…