Logo

Mathematical Sciences Research Institute

Home > Scientific > Colloquia & Seminars > All Colloquia & Seminars > Current

Current Colloquia & Seminars

  1. Arnold Diffusion First Cycle 2

    Location: MSRI: Simons Auditorium
    Speakers: Ke Zhang (University of Toronto)
    Created on Oct 17, 2018 12:10 PM PDT
  2. Combinatorics Seminar: The Hopf monoid of orbit polytopes and its character group

    Location: UC Berkeley Math (Evans Hall 939)
    Speakers: Mariel Supina (University of California, Berkeley)

    A Hopf monoid is an algebraic structure that many families of combinatorial objects share. The collection of multiplicative functions defined on a Hopf monoid forms a group, called the character group. Aguiar and Ardila (2017) proved that the character groups for the Hopf monoids of permutahedra and associahedra are exponential power series under multiplication and composition, respectively. In this talk I will introduce the Hopf monoid of orbit polytopes, and then I will discuss some of my recent work on determining the structure of the character group of this Hopf monoid.

    Updated on Oct 18, 2018 02:17 PM PDT
  3. Arnold Diffusion First Cycle 2

    Location: MSRI: Simons Auditorium
    Speakers: Ke Zhang (University of Toronto)
    Created on Oct 17, 2018 12:14 PM PDT
  4. Hamiltonian Colloquium: Symplectic reduction of the 3-body problem in 4-dimensional space

    Location: MSRI: Simons Auditorium
    Speakers: Holger Dullin (University of Sydney)

    The N-body problem in d-dimension space has symmetry group SE(d).
    Centre of mass reduction leads to a system with SO(d) symmetry acting
    diagonally on positions and momenta. For N=3, d=4 reduction of the SO(4)
    symmetry is complicated because the tensor of inertia is non-invertible.
    The fully reduced system has 4 degrees of freedom and a Hamiltonian that 
    is not polynomial in the momenta. The most surprising property of the 
    reduced Hamiltonian is that it has equilibria that are minima.

    Updated on Oct 03, 2018 09:54 AM PDT