[Alta-Logic] peripatetic seminar tomorrow

[Jonathan Gallagher]

There is a peripatetic seminar meeting tomorrow.

Where and when: ICT 616 Friday, Feb 3 at  12:15 p.m.

Speaker 1: Geoff Vooys

Title: A Categorical Introduction to the Theory of Witt Vectors, Part II

Abstract: The theory of Witt vectors is traditionally used to lift
commutative rings with identity in positive characteristic to commutative
rings with identity in characteristic zero in a way that extends to a
functor from the opposite category of affine schemes to the category of
commutative rings with identity. However, the constructions that define the
ring operations on the ring of Witt vectors are frequently too complicated
to work with in practice, and many of the properties of Witt vectors useful
in arithmetic geometry are frustratingly difficult to derive. In this talk
we will provide an alternative, more categorical, development of Witt
vectors that will make the theory cleaner and clearer, as well as show that
many of the properties of Witt vectors are simple consequences of the
categorical perspective that we will provide. In particular, we will show
that the Witt vector functor arises as a left Kan extension and that the
ring of Ghost components associated a ring of Witt vectors comes from a
natural transformation induced by the universal property of left Kan
extensions.

Speaker 2: TBA

We look forward to seeing you tomorrow!
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