Please not the unusual time and room. -------- Forwarded Message -------- Subject: Re: Mittagsseminar am 24.03.2015 -> 26.03.2015 Date: Mon, 23 Mar 2015 13:49:49 +0100 From: Wolfgang Mulzer <mulzer@inf.fu-berlin.de> To: agti-Mittagsseminar@lists.fu-berlin.de CC: Frédéric Meunier <frederic.meunier@enpc.fr> Since the ERC-workshop is taking place simultaneously at Seminaris, tomorrow's Mittagsseminar has been rescheduled. The new date and time are: Thursday, 26.03.2015 14:00 st Takustr. 9, SR 053 Frédéric Meunier Hedetniemi’s conjecture for Kneser hypergraphs Abstract: One of the most famous conjectures in graph theory is Hedetniemi’s conjecture stating that the chromatic number of the categorical product of graphs is the minimum of their chromatic numbers. Using a suitable extension of the definition of the categorical product, Zhu proposed in 1992 a similar conjecture for hypergraphs. With the help of a technique originally introduced by Jiri Matousek and based on combinatorial counterparts of the Borsuk-Ulam theorem, it is possible to prove that Zhu’s conjecture is true for Kneser hypergraphs, which become the first non-trivial and explicit family of hypergraphs satisfying this conjecture. A similar approach also allows to exhibit new families of graphs that satisfy Hedetniemi’s conjecture. This is joint work with Hossein Hajiabolhassan.
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