Voß, HeinrichHeinrichVoß2022-01-102022-01-102015Lecture Notes in Computational Science and Engineering 103 (): 305-313 (2015)http://hdl.handle.net/11420/11440Variational principles are very powerful tools when studying self-adjoint linear operators on a Hilbert space H. Bounds for eigenvalues, comparison theorems, interlacing results and monotonicity of eigenvalues can be proved easily with these characterizations, to name just a few. In this paper we consider generalization of these principles to families of linear, self-adjoint operators depending continuously on a scalar in a real interval.enMathematikConference Paper10.1007/978-3-319-10705-9_30Other