Department of

# Mathematics

Seminar Calendar
for events the day of Friday, March 16, 2018.

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events for the
events containing

More information on this calendar program is available.
Questions regarding events or the calendar should be directed to Tori Corkery.
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Friday, March 16, 2018

12:00 pm in 443 Altgeld Hall,Friday, March 16, 2018

#### The Complexity of Isomorphism Classes of Banach Spaces

###### Mary Angelica Tursi (UIUC Math)

Abstract: It is commonly known that separable Banach spaces embed isometrically into the separable space $C(\Delta)$, where $\Delta$ is the Cantor set. Taking the Effros-Borel structure $\mathcal F(C(\Delta))$, we can then view the collection of separable Banach spaces as a Borel subset $\mathcal B \subseteq \mathcal F(C(\Delta))$ and consider the existence of an isomorphism between Banach spaces to be an equivalence relation on $\mathcal B$. For this expository talk, I will present some basic descriptive set theoretic techniques used to determine the complexity of isomorphism equivalence classes, in particular the Borel case of the class for $\ell_2$, and a non-Borel analytic case with Pelczynski’s universal space $\mathcal U$.

4:00 pm in 241 Altgeld Hall,Friday, March 16, 2018

#### Operations in complex K theory

###### William Balderrama (UIUC)

Abstract: In nice cases, the correct algebraic setup can exert a large amount of control over a geometric situation. I will illustrate this with the example of complex K theory.

4:00 pm in 345 Altgeld Hall,Friday, March 16, 2018