11 citations · 19 across the 8 of their papers we have counts for
10 papers
Symmetries of Fano varieties
Louis Esser, Lena Ji, Joaquín Moraga
We study Fano varieties endowed with a faithful action of a symmetric group, as well as analogous results for Calabi--Yau varieties, and log terminal singularities. We show the exi…
The fibering genus of Fano hypersurfaces
Nathan Chen, Benjamin Church, Lena Ji +1
Kollár proved that a very general -dimensional complex hypersurface of degree at least is not birational to a fibration in rational curves. This is most…
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…
Fano hypersurfaces with no finite order birational automorphisms
Nathan Chen, Lena Ji, David Stapleton
We use the specialization homomorphism for the birational automorphism group to study finite order birational automorphisms. For a family of varieties over a DVR, we prove that a b…
Rationality of real conic bundles with quartic discriminant curve
Lena Ji, Mattie Ji
We study real double covers of branched over a -divisor, which have the structure of a conic bundle threefold with smooth quartic discriminant…
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…
The Noether--Lefschetz theorem in arbitrary characteristic
Lena Ji
We show that if is a normal variety of dimension and a very general hypersurface of degree or , then the rest…
Structure of geometrically non-reduced varieties
Lena Ji, Joe Waldron
We prove a structural result for geometrically non-reduced varieties and give applications to Fano varieties. For example, we show that if is the generic fibre of a Mori fibre…
Completely Controlling the Dimensions of Formal Fiber Rings at Prime Ideals of Small Height
Sarah M. Fleming, Lena Ji, S. Loepp +3
Let be a complete equicharacteristic local (Noetherian) UFD of dimension or greater. Assuming that , where is the maximal ideal of , we construct a loca…
Controlling the Dimensions of Formal Fibers of a Unique Factorization Domain at the Height One Prime Ideals
Sarah M. Fleming, Lena Ji, S. Loepp +3
Let T be a complete local (Noetherian) equidimensional ring with maximal ideal m such that the Krull dimension of T is at least two and the depth of T is at least two. Suppose that…