- Series
- School of Mathematics Colloquium
- Time
- Tuesday, November 12, 2019 - 11:00am for 1 hour (actually 50 minutes)
- Location
- Skiles 006
- Speaker
- Betsy Stovall – University of Wisconsin – stovall@math.wisc.edu
- Organizer
- Michael Lacey

One strategy for developing a proof of a claimed theorem is to start by understanding what a counter-example should look like. In this talk, we will discuss a few recent results in harmonic analysis that utilize a quantitative version of this approach. A key step is the solution of an inverse problem with the following flavor. Let $T:X \to Y$ be a bounded linear operator and let $0 < a \leq \|T\|$. What can we say about those functions $f \in X$ obeying the reverse inequality $\|Tf\|_Y \geq a\|f\|_X$?