Speaker: Erlend Due Børve

Room: Aud D1 (1535-113)

Titel: Magnitude - from ecology to topology via metric spaces

Abstract: In 1994, the ecologists Solow and Polasky developed a measure of the diversity of an ecological community. It counts the "effective number of species" with respect to genetic variation. By defining the magnitude of a finite metric space as a measure for the "effective number of points," Leinster and co-authors gave mathematical rigour to this idea. The notion of magnitude fits into a much more general framework, providing a "universal invariant" to a wide range of mathematical objects. The Euler characteristic of topological spaces is a notable example.