On the Injective Norm of Sums of Random Tensors and the Moments of Gaussian Chaoses
This work addresses a theoretical problem in probability and high-dimensional statistics, providing incremental improvements to existing bounds.
The paper tackles the problem of bounding the expected ℓ_p injective norm of sums of subgaussian random tensors, achieving a strict improvement over a recent result and sharpening a key bound in the Euclidean case, which leads to an elementary proof of a fundamental result on Gaussian chaoses.
We prove an upper bound on the expected $\ell_p$ injective norm of sums of subgaussian random tensors. Our proof is simple and does not rely on any explicit geometric or chaining arguments. Instead, it follows from a simple application of the PAC-Bayesian lemma, a tool that has proven effective at controlling the suprema of certain ``smooth'' empirical processes in recent years. Our bound strictly improves a very recent result of Bandeira, Gopi, Jiang, Lucca, and Rothvoss. In the Euclidean case ($p=2$), our bound sharpens a result of Latała that was central to proving his estimates on the moments of Gaussian chaoses. As a consequence, we obtain an elementary proof of this fundamental result.