Boundary Value Problems
Volume 2007 (2007), Article ID 48232, 16 pages
Research Article

Liouville Theorems for a Class of Linear Second-Order Operators with Nonnegative Characteristic Form

Alessia Elisabetta Kogoj and Ermanno Lanconelli

Dipartimento di Matematica, Università di Bologna, Piazza di Porta San Donato 5, Bologna 40126, Italy

Received 1 August 2006; Revised 28 November 2006; Accepted 29 November 2006

Academic Editor: Vincenzo Vespri

Copyright © 2007 Alessia Elisabetta Kogoj and Ermanno Lanconelli. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We report on some Liouville-type theorems for a class of linear second-order partial differential equation with nonnegative characteristic form. The theorems we show improve our previous results.