Christian Rosendal: Infinite asymptotic games and an exact Ramsey principle for block sequences

Week 2, Friday June 26, 15:15-16:05

We prove an exact, i.e., formulated without Delta-expansions, Ramsey principle for infinite block sequences in vector spaces over countable fields, where the two sides of the dichotomic principle are represented by respectively winning strategies in Gowers' block sequence game and winning strategies in the infinite asymptotic game. This allows us to recover Gowers' dichotomy theorem for block sequences in normed vector spaces by a simple application of the basic determinacy theorem for infinite asymptotic games.