Special Session 74: Local and Nonlocal Fully Nonlinear Partial Differential Equations of Elliptic and Parabolic Type

Rectifiability for points with positive Alt-Caffarelli-Friedman limit

Mark Allen
Brigham Young University
USA
Co-Author(s):    Dennis Kriventsov, Robin Neumayer
Abstract:
We study the interfacial regularity between a pair of nonnegative subharmonic functions with disjoint positivity sets. The portion of the interface where the Alt-Caffarelli-Friedman (ACF) monotonicity formula is asymptotically positive forms an $\mathcal{H}^{n-1}$ rectifiable set. Moreover, for $\mathcal{H}^{n-1}$-a.e. such point, the two functions have unique blowups, i.e. the Lipschitz rescaling converge in $W^{1,2}$ to a pair of non degenerate truncated linear functions whose supports meet at the approximate tangent plane.