We provide a new formulation of Harnackʼs inequality for nonlocal operators. In contrast to previous versions we do not assume harmonic functions to have a sign. The version of Harnackʼs inequality given here generalizes Harnackʼs classical result from 1887 to nonlocal situations. As a consequence we derive Hölder regularity estimates by an extension of Moserʼs method. The inequality that we propose is equivalent to Harnackʼs original formulation but seems to be new even for the Laplace operator.
Nous fournissons une nouvelle formulation de lʼinégalité de Harnack pour des opérateurs non-locaux. En contraste avec les versions précédentes, nous nʼavons pas à supposer que les fonctions harmoniques sont de signe constant. La version de lʼinégalité de Harnack donnée ici généralise le résultat classique de Harnack datant de 1887 pour les cas non-locaux. Conséquemment, on obtient des estimations de la régularité Hölder grâce à une extension de la méthode de Moser. Lʼinégalité que nous proposons est équivalente à la formulation originale de lʼinégalité de Harnack mais semble être nouvelle y compris pour lʼopérateur de Laplace.
Accepted:
Published online:
Moritz Kassmann 1
@article{CRMATH_2011__349_11-12_637_0, author = {Moritz Kassmann}, title = {A new formulation of {Harnack's} inequality for nonlocal operators}, journal = {Comptes Rendus. Math\'ematique}, pages = {637--640}, publisher = {Elsevier}, volume = {349}, number = {11-12}, year = {2011}, doi = {10.1016/j.crma.2011.04.014}, language = {en}, }
Moritz Kassmann. A new formulation of Harnackʼs inequality for nonlocal operators. Comptes Rendus. Mathématique, Volume 349 (2011) no. 11-12, pp. 637-640. doi : 10.1016/j.crma.2011.04.014. https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.1016/j.crma.2011.04.014/
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