# Events for 04/11/2023 from all calendars

## Several Complex Variables Seminar

**Time: ** 12:50PM - 1:50PM

**Location: ** Zoom

**Speaker: **Achinta Kumar Nandi, Oklahoma State University

**Title: ***On perturbations of singular complex analytic hypervarieties*

**Abstract: **In this talk, we shall discuss an extension and higher dimensional generalization of a result by Lyubich and Peters on perturbations of singular Riemann Surfaces. We will further investigate its higher codimension analog.

## Nonlinear Partial Differential Equations

**Time: ** 3:00PM - 4:00PM

**Location: ** ZOOM

**Speaker: **Xu Yuan, Chinese University of Hong Kong

**Title: ***Construction of multi-solitons for the energy-critical wave equation*

**Abstract: **We will review some results on the construction and interaction of solitary waves for the energy-critical focusing wave equation. After discussing briefly the well-known conjecture of soliton resolution, we will present recent results of the existence of multi-solitary waves in the case of weak interactions.

## Maxson Lecture Series

**Time: ** 4:00PM - 5:00PM

**Location: ** BLOC 117

**Speaker: **Kannan Soundararajan, Stanford University

**Title: ***Covering integers using quadratic forms*

**Abstract: **How large must \Delta be so that we can cover a substantial proportion of the integers below X using the binary quadratic forms x^2 +dy^2 with d below \Delta? Problems involving representations by binary quadratic forms have a long history, going back to Fermat. The particular problem mentioned here was recently considered by Hansen and Vaughan, and Diao. In ongoing work with Ben Green, we resolve this problem, and identify a sharp phase transition: If \Delta is below (log X)^{log 2-\epsilon} then zero percent of the integers below X are represented, whereas if \Delta is above (log X)^{log 2 +\epsilon} then 100 percent of the integers below X are represented. I will give a gentle introduction to some of the ideas involved.