Results 61 to 70 of about 68,205 (182)

Explicit Baker–Campbell–Hausdorff Expansions

Mathematics, 2018
The Baker–Campbell–Hausdorff (BCH) expansion is a general purpose tool of use in many branches of mathematics and theoretical physics. Only in some special cases can the expansion be evaluated in closed form.
Alexander Van-Brunt, Matt Visser
doaj   +1 more source

Cohomogeneity‐one solitons in Laplacian flow: Local, smoothly‐closing and steady solitons

Journal of the London Mathematical Society, Volume 113, Issue 6, June 2026.
Abstract We initiate a systematic study of cohomogeneity‐one solitons in Bryant's Laplacian flow of closed G2$\text{G}_2$‐structures on a 7‐manifold, motivated by the problem of understanding finite‐time singularities of that flow. Here, we focus on solitons with symmetry groups Sp(2)${\rm Sp}(2)$ and SU(3)${\rm SU}(3)$; in both cases, we prove the ...
Mark Haskins, Johannes Nordström
wiley   +1 more source

Lorentzian homogeneous structures with indecomposable holonomy

Journal of the London Mathematical Society, Volume 113, Issue 5, May 2026.
Abstract For a Lorentzian homogeneous space, we study how algebraic conditions on the isotropy group affect the geometry and curvature of the homogeneous space. More specifically, we prove that a Lorentzian locally homogeneous space is locally isometric to a plane wave if it admits an Ambrose–Singer connection with indecomposable, non‐irreducible ...
Steven Greenwood, Thomas Leistner
wiley   +1 more source

A Structural Approach to Relativistic Symmetry: Dual Relativity and the Lorentz–Heisenberg Algebra

Mathematics
This paper studies a realization-theoretic problem inside the standard Lorentz-covariant Fourier-dual framework on L2(R3,1): whether position-space and momentum-space geometric translations can be placed on equal structural footing without leaving the ...
Daniel Rothbaum
doaj   +1 more source

Robust Inverse Material Design With Physical Guarantees Using the Voigt‐Reuss Net

International Journal for Numerical Methods in Engineering, Volume 127, Issue 7, 15 April 2026.
ABSTRACT We apply the Voigt‐Reuss net, a spectrally normalized neural surrogate introduced in [38], for forward and inverse mechanical homogenization with a key guarantee that all predicted effective stiffness tensors satisfy Voigt‐Reuss bounds in the Löwner sense during training, inference, and gradient‐driven optimization.
Sanath Keshav, Felix Fritzen
wiley   +1 more source

Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the String‐Theoretical Swampland Programme

Fortschritte der Physik, Volume 74, Issue 4, April 2026.
Abstract String theory has strong implications for cosmology, implying the absence of a cosmological constant, ruling out single‐field slow‐roll inflation, and that black holes decay. The origins of these statements are elucidated within the string‐theoretical swampland programme.
Kay Lehnert
wiley   +1 more source

Sublinear bilipschitz equivalence and the quasiisometric classification of solvable Lie groups

Journal of the London Mathematical Society, Volume 113, Issue 4, April 2026.
Abstract We prove a product theorem for sublinear bilipschitz equivalences which generalizes the classical work of Kapovich, Kleiner, and Leeb on quasiisometries between product spaces. We employ our product theorem to distinguish up to quasiisometry certain families of solvable groups which share the same dimension, cone‐dimension and Dehn function ...
Ido Grayevsky, Gabriel Pallier
wiley   +1 more source

Failure of stability of a maximal operator bound for perturbed Nevo–Thangavelu means

Mathematika, Volume 72, Issue 2, April 2026.
Abstract Let G$G$ be a two‐step nilpotent Lie group, identified via the exponential map with the Lie‐algebra g=g1⊕g2$\mathfrak {g}=\mathfrak {g}_1\oplus \mathfrak {g}_2$, where [g,g]⊂g2$[\mathfrak {g},\mathfrak {g}]\subset \mathfrak {g}_2$. We consider maximal functions associated to spheres in a d$d$‐dimensional linear subspace H$H$, dilated by the ...
Jaehyeon Ryu, Andreas Seeger
wiley   +1 more source

Hipercomputación desde la computación cuántica

Revista Colombiana de Computación, 2006
Un hipercomputador computa funciones que son incomputables por una máquina de Turing. Recientemente, Tien D. Kieu ha propuesto un algoritmo hipercomputacional cuántico, el cual emplea como referente físico el oscilador armónico cuántico y resuelve en ...
Andrés Sicard, Juan David Suárez Ospina, Mario Vélez   +2 more
doaj  

Accelerating Conjugate Gradient Solvers for Homogenization Problems With Unitary Neural Operators

International Journal for Numerical Methods in Engineering, Volume 127, Issue 5, 15 March 2026.
ABSTRACT Rapid and reliable solvers for parametric partial differential equations (PDEs) are needed in many scientific and engineering disciplines. For example, there is a growing demand for composites and architected materials with heterogeneous microstructures.
Julius Herb, Felix Fritzen
wiley   +1 more source