Results 81 to 90 of about 1,191 (241)

On the Scottish Book Problem 155 by Mazur and Sternbach

Comptes Rendus. Mathématique
Problem 155 of the Scottish Book asks whether every bijection $U\colon X\rightarrow Y$ between two Banach spaces $X, Y$ with the property that, each point of $X$ has a neighborhood on which $U$ is isometric, is globally isometric on $X$.
Mori, Michiya
doaj   +1 more source

SURJECTIVE QUADRATIC JORDAN ALGEBRAS

Eurasian Mathematical Journal, 2020
Summary: We introduce the concepts of surjectivity and linear minimality for quadratic Jordan algebras, then we present a partial classification of such algebras of characteristic 2. As a corollary, we obtain that in substance non-trivial minimal quadratic Jordan algebras are fields.
Baissalov, Yerzhan, Aljouiee, Abdullah
openaire   +2 more sources

Nonlinear Model Order Reduction on Polynomial Manifolds for Computational Homogenisation Problems

Proceedings in Applied Mathematics and Mechanics, Volume 26, Issue 2, June 2026.
ABSTRACT Model order reduction (MOR) techniques utilising nonlinear approximation spaces can search for solutions to computational homogenisation problems on low‐dimensional approximation spaces. In combination with hyperreduction techniques, this allows for computations on representative volume elements (RVEs) to be accelerated by multiple orders of ...
Erik Faust, Lisa Scheunemann
wiley   +1 more source

Counting Degrees of Freedom: A Method Applicable From Scalars to f(Q)$f(\mathbb {Q})$ Gravity and Beyond

Fortschritte der Physik, Volume 74, Issue 6, June 2026.
ABSTRACT We present a clear, step‐by‐step method for counting degrees of freedom and identifying constraints in general field theories. This approach, grounded in the works of Einstein, Hilbert, Cartan, Kuranishi, and, more recently, Seiler, is neither Lagrangian nor Hamiltonian in nature. Instead, it applies directly to the field equations. We offer a
Lavinia Heisenberg
wiley   +1 more source

Kripke's Reduction of Löb's Theorem to the Second Incompleteness Theorem

Theoria, Volume 92, Issue 3, June 2026.
ABSTRACT In this paper, we discuss Kripke's reduction of Löb's Principle to the Second Incompleteness Theorem. We have a closer look at the non‐constructive character of the reduction. We reflect on what the argument has to tell us. In the Appendix, We give a strengthening of Löb's Principle suggested by Kripke's reduction.
Albert Visser
wiley   +1 more source

Existence Result for a Class of Time-Fractional Nonstationary Incompressible Navier–Stokes–Voigt Equations

Axioms
We are devoted in this work to dealing with a class of time-fractional nonstationary incompressible Navier–Stokes–Voigt equation involving the Caputo fractional derivative.
Keji Xu, Biao Zeng
doaj   +1 more source

The complexity of surjective homomorphism problems—a survey

Discrete Applied Mathematics, 2012
We survey known results about the complexity of surjective homomorphism problems, studied in the context of related problems in the literature such as list homomorphism, retraction and compaction. In comparison with these problems, surjective homomorphism problems seem to be harder to classify and we examine especially three concrete problems that have
Manuel Bodirsky, Jan Kára, Barnaby Martin   +2 more
openaire   +5 more sources

On the tightness of left‐invariant contact structures

Bulletin of the London Mathematical Society, Volume 58, Issue 6, June 2026.
Abstract We prove that all left‐invariant contact structures on three‐dimensional Lie groups are tight. The argument is based on Riemannian methods and establishes a unique factorization property for any Lie group admitting a left‐invariant contact structure, other than SU(2)$\mathrm{SU}(2)$. We then make use of such factorization property to construct
Eugenio Bellini
wiley   +1 more source

A surjectivity result for nonlinear mappings on uniform spaces and applications [PDF]

, 1988
The main purpose of the present paper is to establish a surjectivity result for nonlinear continuous mappings on uniform spaces. Then one can prove that every surjective, continuous and expansive map of an uniform space onto itself has a unique fixed ...
Angelov, Vasil G.
core  

Surjectivity of partial differential operators with good fundamental solutions

, 2011
We characterize the surjectivity of a linear partial differential operator with constant coefficients on E(Ω) as well as on D′(Ω) in terms of the existence of “good” shifted fundamental solutions.
Jochen Wengenroth, Wengenroth, Jochen
core   +1 more source