## Math Calendar

Friday, October 30, 2020

14:00-18:00

On Zoom

Dutch Differential Topology and Geometry Seminar

Stephan Mescher - Topological complexity. Introduction and perspectives

see description

Topological complexity is an integer-valued homotopy invariant of topological spaces that is motived by the motion planning problem from robotics and that was introduced by Michael Farber in 2003. I will give an overview over its definition and its most important properties before presenting some explicit computations and connections to other parts of topology and geometry.

Afterwards I will present a variety of results on the topological complexity of configuration spaces that naturally occur in robotics in the study of simultaneous motion planning for multiple robots moving in the same workspace that are supposed not to collide while performing their tasks. In the end, I will present some recent results and outline some current directions of research.

Zoom details can be found in the website of the seminar: https://www.few.vu.nl/~trt800/ddtg.html

Afterwards I will present a variety of results on the topological complexity of configuration spaces that naturally occur in robotics in the study of simultaneous motion planning for multiple robots moving in the same workspace that are supposed not to collide while performing their tasks. In the end, I will present some recent results and outline some current directions of research.

Zoom details can be found in the website of the seminar: https://www.few.vu.nl/~trt800/ddtg.html

Monday, November 2, 2020

10:00-12:00

online

The target audience isbeginning PhD students and anybody with a basic algebraic geometry background and is organized by Carel Faber, Martijn Kool and Marta Pieropan. The first four dates are 12, 19, 26 October and 2 November.

Also see the email sent by Marta on 30 September, 13.38 hrs.

Please contact Marta Pieropan in case you want to participate: email m.pieropan@uu.nl .

Thursday, November 5, 2020

16:00-17:00

TEAMS

Applied Mathematics Seminar -- Karel Devriendt (University of Oxford) Variance and covariance of distributions on graphs

see description

We develop a theory to measure the variance and covariance of probability distributions defined on the nodes of a graph, which takes into account the distance between nodes. Our approach generalizes the usual (co)variance to the setting of weighted graphs and retains many of its intuitive and desired properties. Interestingly, we find that a number of famous concepts in graph theory and network science can be reinterpreted in this setting as variances and covariances of particular distributions: we show this correspondence for Kemeny's constant, the Kirchhoff index, network modularity and Markov stability. As a particular application, we define the maximum-variance problem on graphs with respect to the effective resistance distance, and characterize the solutions to this problem both numerically and theoretically. We show how the maximum-variance distribution can be interpreted as a core-periphery measure, illustrated by the fact that these distributions are supported on the leaf nodes of tree graphs, low-degree nodes in a configuration-like graph and boundary nodes in random geometric graphs. Our theoretical results are supported by a number of experiments on a network of mathematical concepts, where we use the variance and covariance as analytical tools to study the (co-)occurrence of concepts in scientific papers with respect to the (network) relations between these concepts.

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Teams link:

https://teams.microsoft.com/l/channel/19%3a733c0a3bcaa0431b8412e23f94881e41%40thread.tacv2/05.10.2020%2520--%2520Karel%2520Devriendt%2520(Oxford)?groupId=b99be15b-b162-429c-8b94-0ce54d2319d3&tenantId=d72758a0-a446-4e0f-a0aa-4bf95a4a10e7

Code: ypd7t2y

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Friday, November 6, 2020

16:30-17:30

On Zoom

Tuesday, November 10, 2020

16:00-18:00

On Zoom

TBA

Website of the seminar: http://utrechtgeometrycentre.nl/ugc-seminar/

Zoom details will be sent by email to the staff and student mailing lists a few days before the event.

Website of the seminar: http://utrechtgeometrycentre.nl/ugc-seminar/

Zoom details will be sent by email to the staff and student mailing lists a few days before the event.

Friday, November 13, 2020

16:30-17:30

On Zoom

17:30-18:30

On Zoom

Friday Fish Seminar

Wilmer Smilde - The local nature of Poisson diffeomorphism groups

see description

TBA

Zoom details are sent in the weekly announcements. To join the mailing list you can drop us an email to fridayfishseminar[at]gmail.com.

Website of the seminar: http://utrechtgeometrycentre.nl/friday-fish-seminar-online-edition/

Zoom details are sent in the weekly announcements. To join the mailing list you can drop us an email to fridayfishseminar[at]gmail.com.

Website of the seminar: http://utrechtgeometrycentre.nl/friday-fish-seminar-online-edition/

Thursday, November 26, 2020

16:00-17:00

TEAMS

Thursday, December 3, 2020

16:00-17:00

TEAMS

Tuesday, December 8, 2020

16:00-18:00

On Zoom

Website of the seminar: http://utrechtgeometrycentre.nl/ugc-seminar/

Zoom details will be sent by email to the staff and student mailing lists a few days before the event.

Thursday, December 17, 2020