Boundary Value Problems 
Volume 2007 (2007), Article ID 48232, 16 pages
doi:10.1155/2007/48232
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

Recommended by Vincenzo Vespri

Abstract

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.