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Sums of squares II: matrix functions by Korobenko, Lyudmila; Sawyer, Eric T. is a scholarly article available to read on EtoBox.

What is Sums of squares II: matrix functions about?

This is the second in a series of three papers dealing with sums of squares and hypoellipticity in the infinitely degenerate regime. We give sharp conditions on the entries of a positive semidefinite NxN matrix function F on n-dimensional Euclidean space, whose determinant vanishes only at the origin and such that F is comparable to its diagonal matrix, in order that F is a finite sum of squares of C^2,delta vector fields. We also consider slightly more general decompositions in which a single quasiconformal term need not be a sum of squares.

Author

Korobenko, Lyudmila; Sawyer, Eric T.

Published

2021

Language

EN