Prof. Emo Welzl and Prof. Bernd Gärtner
|Mittagsseminar Talk Information|
Date and Time: Thursday, September 26, 2013, 12:15 pm
Duration: 30 minutes
Location: CAB G51
Speaker: Mike Molloy (University of Toronto)
Over the past decade, much of the work on random graph colouring, random k-SAT, and other random constraint satisfaction problems has focussed on some foundational unproven hypotheses that have arisen from statistical physics. Some of the most important such hypotheses concern the "clustering" of solutions.
In the context of colourings: It is believed that if the edge-density is sufficiently high then the colourings of a random graph can be partitioned into clusters that are, in some sense, both well-connected and well-separated. Furthermore, clusters contain a linear number of "frozen vertices", whose colours remain fixed amongst all the colourings in a cluster. The density above which such clusters appear corresponds to an "algorithmic barrier", above which no algorithm has been proven to find a colouring.
In this talk, we determine the exact value of the "freezing threshold", i.e. the edge-density at which frozen vertices appear.
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