YouTube recording: https://www.youtube.com/watch?v=nALiEDYterk
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Time: Wednesday, Jan 24 at 3pm ET
Zoom: https://gatech.zoom.us/j/8802082683
Speaker: James Davies, University of Cambridge
Title: Odd distances in colourings of the plane
Abstract: We prove that every finite colouring of the plane contains a monochromatic pair of points at an odd integer distance from each other. The proof uses a spectral method.
Please advertise this talk at your home institution. Anyone is welcome to attend!
YouTube recording: https://www.youtube.com/watch?v=aOpvWW1lBH8
Time: Wednesday, Nov 15 at 3pm ET
Zoom: https://gatech.zoom.us/j/8802082683
Speaker: Jim Geelen, University of Waterloo
Title: Average plane-size
Abstract: In 1941, Eberhard Melchior proved that the average line-length of a simple rank-3 real-representable matroid is less than three. We discuss a long-overdue analogue of Melchior’s result that the average plane-size of a simple rank-4 real-representable matroid is bounded above by an absolute constant, unless the matroid is the direct-sum of two lines. This is joint work with Rutger Campbell and Matthew Kroeker.
Youtube recording: https://www.youtube.com/watch?v=hr17_7c2QSo
Please advertise this talk at your home institution. Anyone is welcome to attend!
Time: Wednesday, Oct 18 at 3pm ET
Zoom: https://gatech.zoom.us/j/8802082683
Speaker: Kathryn Nurse, Simon Fraser University
Title: Seymour’s 6-flow theorem – a short proof
Abstract: Tutte conjectured in 1954 that every bridgeless graph has a nowhere-zero 5-flow. In 1982, Seymour showed that it is true when 5 is replaced with 6. In this talk, I present a short variation of Seymour’s proof. This work is joint with Matt DeVos.
YouTube recording: https://www.youtube.com/watch?v=zxNG3ksK76w
Please advertise this talk at your home institution. Anyone is welcome to attend!
Time: Wednesday, Sep 20 at 3pm ET
Zoom: https://gatech.zoom.us/j/8802082683
Speaker: Nathan Bowler, Universität Hamburg
Title: The $K_4$ game
Abstract: Two players alternately claim edges of a complete graph on infinitely many vertices. The first to claim all edges of a $K_4$ wins. Can the first player force a win? I will explain the history of this question, why it is harder than it seems, and how to win this game.