On the constants for some Sobolev imbeddings

<p/> <p>We consider the imbedding inequality <inline-formula><graphic file="1029-242X-2001-823805-i1.gif"/></inline-formula> is the Sobolev space (or Bessel potential space) of <inline-formula><graphic file="1029-242X-2001-823805-i2.gif"/>...

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Main Authors: Pizzocchero Livio, Morosi Carlo
Format: Article
Language:English
Published: SpringerOpen 2001-01-01
Series:Journal of Inequalities and Applications
Subjects:
Online Access:http://www.journalofinequalitiesandapplications.com/content/6/823805
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author Pizzocchero Livio
Morosi Carlo
author_facet Pizzocchero Livio
Morosi Carlo
author_sort Pizzocchero Livio
collection DOAJ
description <p/> <p>We consider the imbedding inequality <inline-formula><graphic file="1029-242X-2001-823805-i1.gif"/></inline-formula> is the Sobolev space (or Bessel potential space) of <inline-formula><graphic file="1029-242X-2001-823805-i2.gif"/></inline-formula> type and (integer or fractional) order <inline-formula><graphic file="1029-242X-2001-823805-i3.gif"/></inline-formula>. We write down upper bounds for the constants <inline-formula><graphic file="1029-242X-2001-823805-i4.gif"/></inline-formula>, using an argument previously applied in the literature in particular cases. We prove that the upper bounds computed in this way are in fact the sharp constants if <inline-formula><graphic file="1029-242X-2001-823805-i5.gif"/></inline-formula>, <inline-formula><graphic file="1029-242X-2001-823805-i6.gif"/></inline-formula>, and exhibit the maximising functions. Furthermore, using convenient trial functions, we derive lower bounds on <inline-formula><graphic file="1029-242X-2001-823805-i7.gif"/></inline-formula> for <inline-formula><graphic file="1029-242X-2001-823805-i8.gif"/></inline-formula> in many cases these are close to the previous upper bounds, as illustrated by a number of examples, thus characterizing the sharp constants with little uncertainty.</p>
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spelling doaj.art-302fec60347946ea9bab655a77141f2e2022-12-21T19:00:50ZengSpringerOpenJournal of Inequalities and Applications1025-58341029-242X2001-01-0120016823805On the constants for some Sobolev imbeddingsPizzocchero LivioMorosi Carlo<p/> <p>We consider the imbedding inequality <inline-formula><graphic file="1029-242X-2001-823805-i1.gif"/></inline-formula> is the Sobolev space (or Bessel potential space) of <inline-formula><graphic file="1029-242X-2001-823805-i2.gif"/></inline-formula> type and (integer or fractional) order <inline-formula><graphic file="1029-242X-2001-823805-i3.gif"/></inline-formula>. We write down upper bounds for the constants <inline-formula><graphic file="1029-242X-2001-823805-i4.gif"/></inline-formula>, using an argument previously applied in the literature in particular cases. We prove that the upper bounds computed in this way are in fact the sharp constants if <inline-formula><graphic file="1029-242X-2001-823805-i5.gif"/></inline-formula>, <inline-formula><graphic file="1029-242X-2001-823805-i6.gif"/></inline-formula>, and exhibit the maximising functions. Furthermore, using convenient trial functions, we derive lower bounds on <inline-formula><graphic file="1029-242X-2001-823805-i7.gif"/></inline-formula> for <inline-formula><graphic file="1029-242X-2001-823805-i8.gif"/></inline-formula> in many cases these are close to the previous upper bounds, as illustrated by a number of examples, thus characterizing the sharp constants with little uncertainty.</p>http://www.journalofinequalitiesandapplications.com/content/6/823805Sobolev spacesImbedding inequalities
spellingShingle Pizzocchero Livio
Morosi Carlo
On the constants for some Sobolev imbeddings
Journal of Inequalities and Applications
Sobolev spaces
Imbedding inequalities
title On the constants for some Sobolev imbeddings
title_full On the constants for some Sobolev imbeddings
title_fullStr On the constants for some Sobolev imbeddings
title_full_unstemmed On the constants for some Sobolev imbeddings
title_short On the constants for some Sobolev imbeddings
title_sort on the constants for some sobolev imbeddings
topic Sobolev spaces
Imbedding inequalities
url http://www.journalofinequalitiesandapplications.com/content/6/823805
work_keys_str_mv AT pizzoccherolivio ontheconstantsforsomesobolevimbeddings
AT morosicarlo ontheconstantsforsomesobolevimbeddings