On the monotone properties of general affine surface areas under the Steiner symmetrization

Abstract

In this paper, we prove that, if functions (concave) $ϕ$ and (convex) $ψ$ satisfy certain conditions, the $L_ϕ$ affine surface area is monotone increasing, while the $L_ψ$ affine surface area is monotone decreasing under the Steiner symmetrization. Consequently, we can prove related affine isoperimetric inequalities, under certain conditions on $ϕ$ and $ψ$, without assuming that the convex body involved has centroid (or the Santaló point) at the origin.