Inequalities for Lp -Norms that Sharpen the Triangle Inequality and Complement Hanner’s Inequality

Eric A. Carlen, Rupert L. Frank, Paata Ivanisvili, Elliott H. Lieb

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

In 2006 Carbery raised a question about an improvement on the naïve norm inequality ‖f+g‖pp≤2p-1(‖f‖pp+‖g‖pp) for two functions f and g in Lp of any measure space. When f= g this is an equality, but when the supports of f and g are disjoint the factor 2 p-1 is not needed. Carbery’s question concerns a proposed interpolation between the two situations for p> 2 with the interpolation parameter measuring the overlap being ‖ fg‖ p/2. Carbery proved that his proposed inequality holds in a special case. Here, we prove the inequality for all functions and, in fact, we prove an inequality of this type that is stronger than the one Carbery proposed. Moreover, our stronger inequalities are valid for all real p≠ 0.

Original languageEnglish (US)
Pages (from-to)4051-4073
Number of pages23
JournalJournal of Geometric Analysis
Volume31
Issue number4
DOIs
StatePublished - Apr 2021

All Science Journal Classification (ASJC) codes

  • Geometry and Topology

Keywords

  • Convexity
  • L space
  • Minkowski’s inequality

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