Thursday, June 24, 2021

2:00 p.m. (sharp)

PhD Candidate: Jamal Kawach

Supervisor: Stevo Todorcevic

Thesis title: Approximate Ramsey Methods in Functional Analysis

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We study various aspects of approximate Ramsey theory and its interactions with functional analysis. In particular, we consider approximate versions of the structural Ramsey property and the amalgamation property within the context of multi-seminormed spaces, Fréchet spaces and other related structures from functional analysis. Along the way, we develop the theory of Fraïssé limits of classes of finitedimensional Fréchet spaces, and we prove a version of the Kechris-Pestov-Todorčević correspondence relating the approximate Ramsey property to the topological dynamics of the isometry groups of certain

infinite-dimensional Fréchet spaces. Motivated by problems regarding the structural Ramsey theory of Banach spaces, we study various generalizations of the Dual Ramsey Theorem of Carlson and Simpson.

Specifically, using techniques from the theory of topological Ramsey spaces we obtain versions of the Dual Ramsey Theorem where ω is replaced by an arbitrary countable ordinal. Moving toward block Ramsey theory, we prove an infinite-dimensional version of Gowers’ approximate Ramsey theorem concerning the oscillation stability of S(c0), the unit sphere of the Banach space c0. We then show that results of this form can be parametrized by products of infinitely many perfect sets of reals, and we use this result to

obtain a parametrized version of Gowers’ c0 theorem.

A copy of the thesis can be found here: Kawach ut-thesis

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