2-innerproduct spaces and Gâteaux partial derivatives
A characterization of Gaussian law in Hilbert space.
A characterization of generalized inner product spaces (?-orthogonally additive mappings, III).
A classification of projectors
A positive operator A and a closed subspace of a Hilbert space ℋ are called compatible if there exists a projector Q onto such that AQ = Q*A. Compatibility is shown to depend on the existence of certain decompositions of ℋ and the ranges of A and . It also depends on a certain angle between A() and the orthogonal of .
A formula for angles between subspaces of inner product spaces.
A generalization of parallel addition.
A Grüss type inequality for sequences of vectors in inner product spaces and applications.
À la recherche de la preuve perdue: a simple proof of the Ficken theorem
A new proof of the Ficken criterion is given together with a comment concerning the known proofs and related results
A new type of orthogonality for normed planes
In this paper we introduce a new type of orthogonality for real normed planes which coincides with usual orthogonality in the Euclidean situation. With the help of this type of orthogonality we derive several characterizations of the Euclidean plane among all normed planes, all of them yielding also characteristic properties of inner product spaces among real normed linear spaces of dimensions .
A note on normability of locally convex spaces
A note on spaces of holomorphic vector valued functions with the strict topology.
A potpourri of Schwarz related inequalities in inner product spaces. II.
A potpourri of Schwarz related inequalities in inner product spaces. I.
A product of three projections
Let X and Y be two closed subspaces of a Hilbert space. If we send a point back and forth between them by orthogonal projections, the iterates converge to the projection of the point onto the intersection of X and Y by a theorem of von Neumann. Any sequence of orthoprojections of a point in a Hilbert space onto a finite family of closed subspaces converges weakly, according to Amemiya and Ando. The problem of norm convergence was open for a long time. Recently Adam Paszkiewicz...
A refinement of Hölder's inequality and applications.
A remark on the retracting of a ball onto a sphere in an infinite dimensional Hilbert space.
A remark on the weak topology of the Hilbert space
A Remark on Two Hilbert Space Scattering Theory.
A Riccati equation arising in a boundary control problem for distributed parameters
Si prova resistenza locale della soluzione di una equazione di Riccati che si incontra in un problema di controllo ottimale. In ipotesi di regolarità per il costo si prova resistenza globale. Il problema astratto considerato è il modello di alcuni problemi di controllo ottimale governati da equazioni paraboliche con controllo sulla frontiera.
A short proof of Dvoretzky's theorem