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In this technical report, rigorous statements and formal proofs are presented for both foundational and advanced folklore theorems on the Radon-Nikodym derivative. The cases of conditional and marginal probability measures are carefully…

Information Theory · Computer Science 2025-07-11 Yaiza Bermudez , Gaetan Bisson , Iñaki Esnaola , Samir M. Perlaza

Brehm's extension theorem states that a non-expansive map on a finite subset of a Euclidean space can be extended to a piecewise-linear map on the entire space. In this note, it is verified that the proof of the theorem is constructive…

Metric Geometry · Mathematics 2016-10-04 Pavel Osinenko

We study mapping cones and their dual cones of positive maps of the n by n matrices into itself. For a natural class of cones there is a close relationship between maps in the cone, super-positive maps, and separable states. In particular…

Operator Algebras · Mathematics 2017-03-23 Erling Størmer

Hypermaps were introduced as an algebraic tool for the representation of embeddings of graphs on an orientable surface. Recently a bijection was given between hypermaps and indecomposable permutations; this sheds new light on the subject by…

Combinatorics · Mathematics 2008-12-03 Robert Cori

For any given natural $d\ge 1$ we provide examples of rational self-maps of complex projective plane $\pp^2$ of degree $d$ without (holomorphic) fixed points. This makes a contrast with the situation in one dimension. We also prove that the…

Complex Variables · Mathematics 2010-03-01 Sergey Ivashkovich

The structural invariant subspaces of the discrete-time singular Hamiltonian system are used in 1] to give an analytic nonrecursive expression of all the admissible trajectories. A deeper insight into the features of these subspaces,…

Systems and Control · Computer Science 2012-10-31 Giovanni Marro

Consider the (formal/analytic/algebraic) map-germs Maps(X,(k^p,o)). Let G be the group of right/contact/left-right transformations. I extend the following (classical) results from the real/complex-analytic case to the case of arbitrary…

Algebraic Geometry · Mathematics 2022-09-13 Dmitry Kerner

Nonexpansive mappings play a central role in modern optimization and monotone operator theory because their fixed points can describe solutions to optimization or critical point problems. It is known that when the mappings are sufficiently…

Functional Analysis · Mathematics 2020-04-28 Salihah Alwadani , Heinz H. Bauschke , Xianfu Wang

Admissible vectors lead to frames or coherent states under the action of a group by means of square integrable representations. This work shows that admissible vectors can be seen as weights with central support on the (left) group von…

Functional Analysis · Mathematics 2021-01-19 F. Gomez-Cubillo

The monography examines the problem of constructing a group of automorphisms of a graph. A graph automorphism is a mapping of a set of vertices onto itself that preserves adjacency. The set of such automorphisms forms a vertex group of a…

History and Overview · Mathematics 2024-07-18 Sergey Kurapov , Maxim Davidovsky

We clarify the relation between inverse systems, the Radon-Nikodym property, the Asymptotic Norming Property of James-Ho, and the GFDA spaces introduced in our earlier paper on differentiability of Lipschitz maps into Banach spaces.

Functional Analysis · Mathematics 2011-11-10 Jeff Cheeger , Bruce Kleiner

In this continuation of \cite{BDS}, we investigate the deformations of holomorphic Cartan geometries where the underlying complex manifold is allowed to move. The space of infinitesimal deformations of a flat holomorphic Cartan geometry is…

Differential Geometry · Mathematics 2022-01-25 Indranil Biswas , Sorin Dumitrescu , Georg Schumacher

We study the geometry and holonomy of semi-Riemannian, time-like metric cones that are indecomposable, i.e., which do not admit a local decomposition into a semi-Riemannian product. This includes irreducible cones, for which the holonomy…

Differential Geometry · Mathematics 2022-04-14 Dmitri Alekseevsky , Vicente Cortés , Thomas Leistner

This paper concentrates on optical Hamiltonian systems of $T*\T^n$, i.e. those for which $\Hpp$ is a positive definite matrix, and their relationship with symplectic twist maps. We present theorems of decomposition by symplectic twist maps…

Dynamical Systems · Mathematics 2009-09-25 Christopher Golé

We generalize a preceding simple proof of the Jamiolkowski criterion to check whether a given linear map between algebras of operators is completely positive or not. The generalization is performed to embrace all algebras of Hilbert-Schmidt…

Mathematical Physics · Physics 2007-05-23 D. Salgado , J. L. Sanchez-Gomez

Introducing the deformation theory of holomorphic Cartan geometries, we compute infinitesimal automorphisms and infinitesimal deformations. We also prove the existence of a semi-universal deformation of a holomorphic Cartan geometry.

Differential Geometry · Mathematics 2020-04-01 Indranil Biswas , Sorin Dumitrescu , Georg Schumacher

In this paper we present a generalization of the Radon-Nikodym theorem proved by Pedersen and Takesaki. Given a normal, semifinite and faithful (n.s.f.) weight $\phi$ on a von Neumann algebra M and a strictly positive operator $\delta$,…

Operator Algebras · Mathematics 2007-05-23 Stefaan Vaes

Maps that are not completely positive (CP) are often useful to describe the dynamics of open systems. An apparent violation of complete positivity can occur because there are prior correlations of the principal system with the environment,…

Quantum Physics · Physics 2008-04-21 Hilary Carteret , Daniel R. Terno , Karol Zyczkowski

Nonholonomic mechanics describes the motion of systems constrained by nonintegrable constraints. One of its most remarkable properties is that the derivation of the nonholonomic equations is not variational in nature. {However, in} this…

Mathematical Physics · Physics 2020-10-26 Alexandre Anahory Simoes , Juan Carlos Marrero , David Martin de Diego

Consider a unital C*-algebra A, a von Neumann algebra M, a unital sub-C*-algebra C of A and a unital *-homomorphism $\pi$ from C to M. Let u: A --> M be a decomposable map (i.e. a linear combination of completely positive maps) which is a…

Operator Algebras · Mathematics 2014-04-07 Christian Le Merdy , Lina Oliveira
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