Past Seminars- Number Theory

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  • Travis Scholl
    Thu Oct 11, 2018
    3:00 pm
    In this talk we will focus on constructing "super-isolated abelian varieties". These are abelian varieties that have isogeny class which contains a single isomorphism class. Their motivation comes from security concerns in elliptic and hyperelliptic curve cryptography. Using a theorem of Honda and Tate, we transfer the problem of finding...
  • Jacob Tsimerman
    Thu Oct 4, 2018
    3:00 pm
    The class group is a natural abelian group one can associate to a number field, and it is natural to ask how it varies in families. Cohen and Lenstra famously proposed a model for families of quadratic fields based on random matrices of large rank, and this was later generalized by Cohen-Martinet. However, their model was observed by Malle to have...
  • Zev Klagsbrun
    Thu May 31, 2018
    3:00 pm
    We determine the average size of the Φ-Selmer group in any quadratic twist family of abelian varieties having an isogeny Φ of degree 3 over any number field. This has several applications towards the rank statistics in such families of quadratic twists. For example, it yields the first known quadratic twist families of absolutely...
  • Vadim Ponomarenko
    Thu May 24, 2018
    3:00 pm
    Since Fermat characterized (without proof) those integers represented by the quadratic form x^2+y^2, number theorists have been extending these results.  Recently a paper appeared in Journal of Number Theory answering the question for x^2 ± xy ± y^2.  It turns out that this was not news (although JNT refuses to...
  • Daqing Wan
    Thu May 17, 2018
    3:00 pm
    Given a global function field K of characteristic p>0, the fundamental arithmetic invariants include the genus, the class number, the p-rank and more generally the slope sequence of the zeta function of K. In this expository lecture, we explore possible stability of these invariants in a p-adic Lie tower of K. Strong stability is expected when...
  • Weiyan Chen
    Tue Apr 17, 2018
    3:00 pm
    It is a classical topic dating back to Maclaurin (1698–1746) to study certain special points on smooth cubic plane curves, such as the 9 inflection points (Maclaurin and Hesse), the 27 sextatic points (Cayley), and the 72 points "of type 9" (Gattazzo). Motivated by these algebro-geometric constructions, we ask the following...
  • Bryden Cais
    Thu Apr 12, 2018
    3:00 pm
    Let Y --> X be a branched G-covering of curves over a field k.  The genus of X and the genus of Y are related by the famous Hurwitz genus formula.  When k is perfect of characteristic p and G is a p-group, one also has the Deuring-Shafarevich formula which relates the p-rank of X to that of Y.  In this talk, we will discuss...