Seminar series
Date
Mon, 25 Nov 2019
15:45
15:45
Location
L6
Speaker
Ivan Smith
Organisation
Cambridge
The homological monodromy of the universal family of cubic threefolds defines a representation of a certain Artin-type group into the symplectic group Sp(10;\Z). We use Thurston’s classification of surface automorphisms to prove this does not factor through the genus five mapping class group. This gives a geometric group theory perspective on the well-known irrationality of cubic threefolds, as established by Clemens and Griffiths.