Table of Contents
ISRN Mathematical Analysis
Volume 2011, Article ID 469795, 14 pages
Research Article

Connecting Classical and Abstract Theory of Friedrichs Systems via Trace Operator

1Department of Mathematics, University of Zagreb, Bijenička cesta 30, 10002 Zagreb, Croatia
2Department of Mathematics, University of Osijek, Trg Ljudevita Gaja 6, 31000 Osijek, Croatia

Received 4 May 2011; Accepted 5 June 2011

Academic Editors: D. Han and G. Schimperna

Copyright © 2011 Nenad Antonić et al. 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.


Based on recent progress in understanding the abstract setting for Friedrichs symmetric positive systems by Ern et al. (2007), as well as Antonić and Burazin (2010), we continue our efforts to relate these results to the classical Friedrichs theory. Following the approach via the trace operator, we extend the results of Antonić and Burazin (2011) to situations where the important boundary field does not consist only of projections, allowing the treatment of hyperbolic equations, besides the elliptic ones.