There are numerous min-max principles about the eigenvalues of a Hermitian matrix. The most general ones are Wielandt’s min-max principles which include the Courant-Fisher min-max principles and the trace minimization principles as special cases. In this paper, various extensions of Wielandt’s principles are obtained for a positive semi-definite pencil A − λB by which we mean that A and B are H...

We explicitly express the spectral determinant of Friederichs Dirichlet Laplacians on 2-dimensional hyperbolic (Gaussian curvature -1) cones in terms cone angle and geodesic radius boundary. The related results recent paper "Riemann-Roch isometries non-compact orbifold setting," J. Eur. Math. Soc. 22 (2020) by G. Freixas i Montplet A. von Pippich turn out to be incorrect.

Regesten Kaiser Friedrichs III. (1440-1493). Nach Archiven geordnet, hrsg. v. H. Koller, P.-J. Heinig und A. Niederstätter, Heft 14: Die Urkunden Briefe aus Bibliotheken der Stadt Nürnberg, Teil 1: 1440-1449, bearb. D. Rübsamen, Wien/Weimar/Köln (Böhlau) 2000. 371 S.