The International Society on General Relativity and Gravitation organized an online event to honor Yvonne Choquet-Bruhat on the occasion of her 100th birthday.

There was a talk by Lydia Bieri with the following title and abstract:

**From the initial value problem for the Einstein equations to gravitational waves**

*Yvonne Choquet-Bruhat has been a pioneer bridging mathematics and physics in General Relativity, starting with her 1952 breakthrough result on the initial value problem for the Einstein equations. This result also established the first proof that gravitational waves exist in the nonlinear theory; which had been debated after Albert Einstein in 1916 had found wave solutions for the linearized equations. In this talk, I will highlight the physical and mathematical implications of Yvonne’s work for the understanding of gravitational waves. Starting with her 1952 results, we shall consider her studies of hyperbolic partial differential equations and the propagation of waves, as well as her method developed to study waves propagating in and interacting with a background, where the wavelengths of the waves are substantially shorter than the length scale at which the background changes. Finally, we shall put this into perspective vis-à-vis today’s research on gravitational waves.*

This was followed by a talk by Thibault Damour with the title and abstract:

**Yvonne Choquet-Bruhat: a Mathematician in Einstein’s Universe**

*A brief introduction to a few of Yvonne Choquet-Bruhat’s many fundamental contributions to both the mathematical and the physical understanding of Einstein’s theory of gravitation will be presented.*

FInally we had a talk by Sergiu Klainerman with the title and abstract:

**On the legacy of Yvonne’s foundational 1952 Acta paper**

*I will quickly describe the paper and then concentrate on some of the more recent results concerning the evolution problem in General Relativity.*

The Zoom session was recorded and posted on YouTube.

Last but not least, here is a link to Lydia’s beautiful review of Yvonne’s book *A Lady Mathematician in this
Strange Universe: Memoirs*.