Electronic Journal of Differential Equations,
Vol. 2013 (2013), No. 143, pp. 1-7.

Title: Picone's identity for a system of first-order nonlinear partial
       differential equations
        
Authors: Jaroslav Jaros (Comenius Univ. Bratislava, Slovakia)

Abstract:
 We established a Picone identity for  systems of nonlinear
 partial differential equations of first-order.
 With the help of this formula, we obtain  qualitative results
 such as an integral inequality of Wirtinger type and the existence
 of zeros for the  first components of solutions in a given bounded domain.

Submitted March 31, 2013. Published June 22, 2013.
Math Subject Classifications: 35B05.
Key Words: Nonlinear differential system; Picone identity; Wirtinger inequality.