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Graduate Student Seminar | Santiago Velazquez Iannuzzelli (Northwestern University)

Friday, February 20, 2026 | 4:00 PM - 5:15 PM CT
Lunt Hall, 105, 2033 Sheridan Road, Evanston, IL 60208 map it

Title: Ultrafun with Ultrafilters


Abstract: An ultrafilter is a way of deciding, for any subset of an index set, whether it is "large" or "small". We'll introduce this from scratch and, permitting time, then use it to do two fun things. First, we'll prove the Ax-Grothendieck theorem: any injective polynomial map \mathbb{C}^n \to \mathbb{C}^n is surjective; Second, we'll construct the hyperreal numbers and use them to give the infinitesimal proof of the chain rule that every calculus student wishes they could write.

 

Note: The talk will start at 4:10 pm

Audience

  • Faculty/Staff
  • Student
  • Public
  • Post Docs/Docs
  • Graduate Students

Contact

Daniel Mallory
Email

Interest

  • Academic (general)

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