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Hydra Groups
Algebra & Discrete Mathematics| Speaker: | Tim Riley, Cornell |
| Location: | 1147 MSB |
| Start time: | Fri, Jan 22 2010, 1:10PM |
Description
I will describe some wild geometry that arises in an apparently benign group
theoretic setting: I will exhibit a family of groups enjoying a number of
restrictive geometric and algebraic conditions (they are CAT(0),
bi-automatic, 1-relator, and free-by-cyclic), and yet these groups have free
subgroups of huge (Ackermannian) distortion. The origin of this behaviour
lies in a simple computational game --- a realisation of Hercules' battle with the hydra, played out in manipulations of strings of letters. This is
work with Will Dison.