English

Weak Compactness Criterion in $ W^{k, 1} $ with an Existence Theorem of Minimizers

Functional Analysis 2024-12-03 v2

Abstract

There is a rich theory of existence theorems for minimizers over reflexive Sobolev spaces (ex. Eberlein-\v{S}mulian theorem). However, the existence theorems for many variational problems over non-reflexive Sobolev spaces remain underexplored. In this paper, we investigate various examples of functionals over non-reflexive Sobolev spaces. To do this, we prove a weak compactness criterion in Wk,1W^{k,1} that generalizes the Dunford-Pettis theorem, which asserts that relatively weakly compact subsets of L1 L^1 coincide with equi-integrable families. As a corollary, we also extend an existence theorem of minimizers from reflexive Sobolev spaces to non-reflexive ones. This work is also benefited and streamlined by various concepts in category theory.

Keywords

Cite

@article{arxiv.2306.15871,
  title  = {Weak Compactness Criterion in $ W^{k, 1} $ with an Existence Theorem of Minimizers},
  author = {Cheng Chen and Mattie Ji and Yan Tang and Shiqing Zhang},
  journal= {arXiv preprint arXiv:2306.15871},
  year   = {2024}
}

Comments

We added Theorem 3, which significantly simplified the proof of Proposition 9, Corollary 5 and 7, a new section in the appendix cataloging all the notations used, and 3 new figures, with minor edits to improve the flow of the writing