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.
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After the seminar we will take the speaker to lunch at the Grandstand Bar, where we will also be hosting Tara Holm, who will be speaking at the Joint Colloquium afterwards (Carslaw 273 at 2pm). Anyone attending either/both talk/s is welcome to join us for lunch. So I can give the Grandstand accurate numbers, please email me by Thursday February 18 if you plan to attend the lunch.
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See the Algebra Seminar web page for information about other seminars in the series.
James East james.east@sydney.edu.au
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