Universite Paris Diderot – Paris 7

Thu 11 Aug 2016, 4:00pm
Symbolic Dynamics and Ergodic Theory Seminar
ESB 4133 (PIMS library/lounge)

Recognizability of Sadic shifts

ESB 4133 (PIMS library/lounge)
Thu 11 Aug 2016, 4:00pm5:00pm
Abstract
Aperiodic substitutive dynamical systems are recognizable, i.e., given a substitution \zeta and an element x of the twosided shift (X_\zeta, T) generated by \zeta , there is a unique y \in \Omega_\zeta (up to a power of the shift map T) such that x = T^k \zeta(y) for some k. This was shown by Mossé (1996) for primitive substitutions and by Bezuglyi, Kwiatkowski and Medynets (2009) in the general case. We consider shifts generated by a sequence of substitutions, socalled Sadic shifts. This includes shifts generated by morphic words, and we show that certain morphic words are not recognizable. More precisely, there exist substitutions \zeta and \theta such that nontrivial relations \theta(x) = T^k \theta(y) with x, y \in X_\zeta hold. On the other hand, we prove recognizability for a large class of Sadic shifts using Sadic Rauzy fractals.
This is joint work with Valérie Berthé, Jörg Thuswaldner and Reem Yassawi.
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University of Alberta, Edmonton

Thu 18 Aug 2016, 4:00pm
SPECIAL
Earth Science Building ESB 1012

Making Mathematics with needle and thread: Quilts as Mathematical Objects

Earth Science Building ESB 1012
Thu 18 Aug 2016, 4:00pm5:00pm
Details
The connection between textiles and mathematics is intimate but not often explored, possibly because textiles and fiber arts have traditionally been the domain of women while mathematics was viewed as a male endeavour. How times have changed! Today, textiles and mathematics, like art and science, are recognized for their interwoven, complimentary attributes. In this presentation, mathematics professor Gerda de Vries will examine the connection between textiles and mathematics, in the context of both traditional and contemporary quilts. In a sense, every quilt is a mathematical object, by virtue of the fact that it has shape and dimension. But some quilts are more mathematical than others, and in very different ways. She will show how mathematical concepts such as symmetry, fractals, and algorithmic design show up in the world of quilting through serendipitous and intentional design.
This lecture is for a general audience. A background in mathematics is not needed, nor the ability to sew!
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MIT

Thu 25 Aug 2016, 3:00pm
Harmonic Analysis Seminar
MATH 126

Near optimal restriction theorem on random Cantor set.

MATH 126
Thu 25 Aug 2016, 3:00pm4:00pm
Abstract
For any dimension \alpha < n, we define a type of random Cantor set in \mathbb{R}^n and prove near optimal decoupling and restriction bounds. This is jointwork with Izabella Laba.
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