### Rutgers Discrete Mathematics Seminar

Title: A Reverse Minkowski Theorem

Speaker: **Noah Stephens-Davidowitz**, Princeton/IAS

Date: Monday, October 9, 2017 2:00 pm

Location: Hill Center, Room 705, Rutgers University, Busch Campus, Piscataway, NJ

Abstract:
A classical problem in the geometry of numbers asks us to estimate
how many lattice points lie in some ball around the
origin. Minkowski's celebrated theorem gives us a tight lower bound
for this number that depends only on the determinant of the
lattice. (One can think of the determinant as the limit of the density
of lattice points inside large balls--i.e., the "global density" of
the lattice. So, Minkowski's theorem gives a lower bound on a
lattice's "local density" based on its "global density.") We resolve a
conjecture due to Dadush that gives a nearly tight converse to
Minkowski's theoreman upper bound on the number of lattice points in a
ball that depends only on the determinants of sublattices. This
theorem has numerous applications, from complexity theory, to the
geometry of numbers, to the behavior of Brownian motion on flat
tori. Based on joint work with Oded Regev.

See: http://sites.math.rutgers.edu/~ajr224/DM