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Junior Topology
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Shiyu Liang, : Algorithmic compression of surface automorphisms
Wednesday, April 14, 2021, 02:00pm - 03:00pm
The structure of the cobordism group of surface automorphisms has been determined (Bonahon; Edmonds, Ewing, 1982) as an abstract group . However, the isomorphism is nonexplicit that one is not able to determine if a given automorphism represents 0. The obstruction resides in deciding if an automorphism 'compresses', and I will be showing you that there is an algorithm to decide this with some results from hyperbolic geometry (Casson, Long, 1985).

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