Intermediate Cones between the Cones of Positive Semidefinite Forms and Sums of Squares

Charu Goel, Sarah Hess, Salma Kuhlmann

The cone ${\mathcal{P}}_{n+1,2d}$ ($n,d\in \mathbb{N}$) of all positive semidefinite (PSD) real forms in $n+1$ variables of degree $2d$ contains the subcone ${\Sigma }_{n+1,2d}$ of those that…