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, 12:30pm1:30pm
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, 3:15pm4:15pm
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, 3:30pm5:00pm
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Seminar Information Pages
