Talks will be given on zoom, if you have the password you can join here. Please send an email to one of the organizers to get the the password.

If you would like to give a talk, please send the title, abstract and related papers (if available) of your proposed talk to one of the organizers by email.

Organizers: Brandon Seward, Nattalie Tamam

• November 10: Octave Lacourte (Université Lyon 1)

  Title:  A signature for some subgroups of the permutation group of [0,1[.

  Abstract: For every infinite set X we define S(X) as the group of all permutations of X. On its subgroup consisting of all finitely supported permutations there exists a natural group homomorphism signature. However, thanks to an observation of Vitali in 1915, we know that this group homomorphism does not extend to S(X). In the talk we extend the signature on the subgroup of S(X) consisting of all piecewise isometric elements (strongly related to the Interval Exchange Transformation group). This allows us to list all of its normal subgroups and gives also informations about an element of the second cohomology group of some groups.

• November 17: Brandon Seward (UC San Diego)

  Title:   An introduction to the f-invariant

  Abstract:TBA

• November 24: Christopher Shriver (UC Los Angeles)

  Title:TBA

  Abstract:TBA

• December 1 (Joint with the Functional Analysis Seminar): Remi Boutonnet (CNRS/Bordeaux University)

  Title:TBA

  Abstract:TBA

• December 8: Yotam Smilansky (Rutgers University)

  Title:   Multiscale substitution tilings

  Abstract:   Multiscale substitution tilings are a new family of tilings of Euclidean space that are generated by multiscale substitution rules. Unlike the standard setup of substitution tilings, which is a basic object of study within the aperiodic order community and includes examples such as the Penrose and the pinwheel tilings, multiple distinct scaling constants are allowed, and the defining process of inflation and subdivision is a continuous one. Under a certain irrationality assumption on the scaling constants, this construction gives rise to a new class of tilings, tiling spaces and tiling dynamical systems, which are intrinsically different from those that arise in the standard setup. In the talk I will describe these new objects and discuss various structural, geometrical, statistical and dynamical results. Based on joint work with Yaar Solomon.

• January 5: François Le Maître (Institut de Mathématiques de Jussieu-PRG)

  Title:TBA

  Abstract:TBA