SECOND DERIVATIVE TEST FOR ISOMETRIC EMBEDDINGS IN Lp (1997)
by
Alexander Koldobsky
BibTeX
@MISC{Koldobsky97secondderivative,
author = {Alexander Koldobsky},
title = {SECOND DERIVATIVE TEST FOR ISOMETRIC EMBEDDINGS IN Lp},
year = {1997}
}
OpenURL
Abstract
Abstract. An old problem of P. Levy is to characterize those Banach spaces which embed isometrically in Lp. We show a new criterion in terms of the second derivative of the norm. As a consequence we show that, if M is a twice differentiable Orlicz function with M ′(0) = M ′′(0) = 0, then the n-dimensional Orlicz space ℓn M, n ≥ 3 does not embed isometrically in Lp with 0 < p ≤ 2. These results generalize and clear up the recent solution to the 1938 Schoenberg’s problem on positive definite functions. 1.







