201008.4533v1 Blenders

A blender is a closed convex cone of real homogeneous polynomials that is also closed under linear changes of variable. Non-trivial blenders only occur in even degree. Examples include the cones of psd forms, sos forms, convex forms and sums of 2u-th powers of forms of degree v. We present some general properties of blenders and analyze the extremal elements of some speci..