Szukana fraza: [Abstract = "Our aim is to adapt Fletcher\?s filter approach to solve optimal control problems for systems described by nonlinear Partial Differential Equations \(PDEs\) with state constraints. To this end, we propose a number of modifications of the filter approach, which are well suited for our purposes. Then, we discuss possible ways of cooperation between the filter method and a PDE solver, and one of them is selected and tested."]