@article {2017, title = {Complex Friedrichs systems and applications}, number = {SISSA;03/2017/MATE}, year = {2017}, abstract = {We provide a suitable extension of the theory of abstract Friedrichs systems from real Hilbert spaces to the complex Hilbert space setting, which allows for applications to partial differential equations with complex coeffcients. We also provide examples where the involved Hilbert space is not the space of square integrable functions, as it was the case in previous works, but rather its closed subspace or the space Hs(Rd;Cr), for real s. This setting appears to be suitable for particular systems of partial differential equations, such as the Dirac system, the Dirac-Klein-Gordon system, the Dirac-Maxwell system, and the time-harmonic Maxwell system, which are all addressed in the paper. Moreover, for the time-harmonic Maxwell system we also applied a suitable version of the two-field theory with partial coercivity assumption which is developed in the paper.}, url = {http://urania.sissa.it/xmlui/handle/1963/35270}, author = {Nenad Antoni{\'c} and Kre{\v s}imir Burazin and Ivana Crnjac and Marko Erceg} }