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 Events
Paul Tupper
Department of Mathematics, SFU
Tue 25 Apr 2017, 12:30pm
Scientific Computation and Applied & Industrial Mathematics
ESB 4133 (PIMS Lounge)
From Distance to Diversity: Extending the Concept of a Metric Space
ESB 4133 (PIMS Lounge)
Tue 25 Apr 2017, 12:30pm-1:30pm

Abstract


One important construction in the theory of metric spaces is the tight span. The tight span of a metric space can be thought of as a generalization of the idea of a convex hull in linear spaces and is the basis for much work in the study and visualization of finite metric spaces. Motivated by problems in phylogenetics, we have developed a generalization of the concept of metric spaces, which we call diversities. In a diversity, every subset of points in the space corresponds to a number, not just pairs, and there is a more general version of the triangle inequality. Besides encompassing a number of interesting examples as special cases, diversities have a natural tight span construction with corresponding theory. I will give an introduction to tight span theory for metric spaces and then show how it extends to our theory of diversities. I will conclude by demonstrating the relation between diversities and Steiner tree packing in graphs. This is joint work with David Bryant (University of Otago, New Zealand).

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UBC
Wed 26 Apr 2017, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)
Mod 2 homology operations for spectral Lie algebras
ESB 4133 (PIMS Lounge)
Wed 26 Apr 2017, 3:15pm-4:15pm

Abstract

The Goodwillie derivatives of the identity functor on pointed spaces form an operad in spectra that is  very closely related to the Lie operad. I will describe the mod 2 homology operations for algebras over this operad. This talk will not assume prior knowledge of either operads or Goodwillie calculus. Sadly, due to time constraints, it also won't explain any Goodwillie calculus! (Instead I will start from a combinatorial description of the derivatives of the identity functor.)
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Ecole Normale Supérieure de Lyon
Thu 27 Apr 2017, 3:30pm
Number Theory Seminar / PIMS Seminars and PDF Colloquiums
ESB 4127
TBA
ESB 4127
Thu 27 Apr 2017, 3:30pm-5:00pm

Abstract

TBA

(This talk is part of the PIMS focus semester on the mod p Langlands program).
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