Geometric Integration by Parts and Sobolev Spaces on Vector Bundles: A Unified Global Approach
Velázquez-Mendoza Carlos Daniel, Sandoval-Romero María de los Ángeles
TL;DR
This work addresses the global theory of Sobolev spaces on vector bundles over Riemannian manifolds by introducing a higher-order geometric integration by parts formula that yields an explicit, intrinsic characterization of the formal adjoint of the covariant derivative. It provides self-contained, global proofs of the Meyers-Serrin density theorem on general manifolds and, for compact manifolds, streamlined Sobolev embedding and Rellich-Kondrashov results, all built from sharp local-to-global norm equivalences. The approach reframes Sobolev spaces in intrinsic geometric terms, avoiding reliance on elliptic regularity or torus reductions, and yields a robust foundation for global analysis on bundles with potential PDE applications. Overall, the paper unifies and extends key Sobolev-space results to vector bundles via a purely geometric, globally coherent framework.
Abstract
This article develops a unified framework for the theory of Sobolev spaces on vector bundles over Riemannian manifolds. The analytical core of our approach is a rigorous higher-order geometric integration by parts formula, which characterizes the formal adjoint of the covariant derivative. This identity is established for arbitrary manifolds, requiring no assumptions on completeness or compactness. While these results are fundamental to global analysis, explicit and direct proofs are often elusive in the literature or rely on overly sophisticated machinery that overshadows the underlying geometry. To bridge this gap, we establish sharp local-to-global norm equivalence estimates and provide streamlined, self-contained proofs for the Meyers-Serrin theorem on general manifolds, as well as the Sobolev embedding and Rellich-Kondrashov theorems for the compact case. By prioritizing intrinsic global arguments over ad hoc coordinate patching, this work provides a modern and accessible foundation for the study of Sobolev spaces on bundles.
