Interpolation and Extension of Functions
Interpolation and Extension of Functions

Charles Fefferman, Princeton University
What's Happening in Fine Hall
Zoom link: https://princeton.zoom.us/j/93918876391
Passcode: 803011
Let X be your favorite Banach space of continuous functions on R^n. Given a function f:E>R defined on a (possibly awful) subset E in R^n, how can we tell whether f extends to a function F:R^n>R belonging to X? If such an F exists, then how small can we take its norm? What can we say about the derivatives of F at or near points of E? Can we take F to depend linearly on f? Suppose E is finite. Can we compute an F as above? How many computer operations does it take? What if F is allowed to agree only approximately with f ? What if we are allowed to discard a few points of E as "outliers"? Which points should we discard?