Notes on compactness in Lp-spaces on locally compact groups

The main goal of the paper is to provide new insight into compactness in Lp-spaces on locally compact groups. The article begins with a brief historical overview and the current state of literature regarding the topic. Subsequently, we "take a step back" and investigate the Arzel'a-As...

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Detalles Bibliográficos
Autor: Krukowski, Mateusz|||0000-0001-6644-5633
Tipo de recurso: artículo
Fecha de publicación:2023
País:España
Institución:Universitat Autònoma de Barcelona
Repositorio:Dipòsit Digital de Documents de la UAB
Idioma:inglés
OAI Identifier:oai:ddd.uab.cat:280953
Acceso en línea:https://ddd.uab.cat/record/280953
https://dx.doi.org/urn:doi:10.5565/PUBLMAT6722308
Access Level:acceso abierto
Palabra clave:Arzelà-ascoli theorem
Kolmogorov-riesz theorem
Weil theorem
Sudakov theorem
Young's convolution inequality
Descripción
Sumario:The main goal of the paper is to provide new insight into compactness in Lp-spaces on locally compact groups. The article begins with a brief historical overview and the current state of literature regarding the topic. Subsequently, we "take a step back" and investigate the Arzel'a-Ascoli theorem on a non-compact domain together with one-point compactification. The main idea comes in Section 3, where we introduce the "Lp-properties" (Lp-boundedness, Lp-equicontinuity, and Lp-equivanishing) and study their "behaviour under convolution". The paper proceeds with an analysis of Young's convolution inequality, which plays a vital role in the final section. During the "grand finale", all the pieces of the puzzle are brought together as we lay down a new approach to compactness in Lp-spaces on locally compact groups.