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We study the relations between the projective and the almost conformally symplectic structures on a smooth even dimensional manifold. We describe these relations by a single almost conformally symplectic connection with totally trace--free…

Differential Geometry · Mathematics 2017-10-17 Jan Gregorovič

We present SiLU network constructions whose approximation efficiency depends critically on proper hyperparameter tuning. For the square function $x^2$, with optimally chosen shift $a$ and scale $\beta$, we achieve approximation error…

Machine Learning · Computer Science 2026-02-24 Koffi O. Ayena

We give a simple proof of the fact that every diagonalizable operator that has a real spectrum is quasi-Hermitian and show how the metric operators associated with a quasi-Hermitian Hamiltonian are related to the symmetry generators of an…

Quantum Physics · Physics 2009-11-13 Ali Mostafazadeh

This paper is devoted to the construction of a hyperkaehler structure on the complexification of any Hermitian-symmetric affine coadjoint orbit O of a semi-simple L*-group of compact type, which is compatible with the complex symplectic…

Mathematical Physics · Physics 2008-07-15 Alice Barbara Tumpach

We present a new short-recurrence reaidual-optimal Krylov subspace recycling method for sequences of Hermitian systems of linear equations with a fixed system matrix and changing right-hand sides. Such sequences of linear systems occur…

Numerical Analysis · Mathematics 2016-04-15 Martin Peter Neuenhofen , Sven Groß

Certificates to a linear algebra computation are additional data structures for each output, which can be used by a-possibly randomized- verification algorithm that proves the correctness of each output. Wiede-mann's algorithm projects the…

Symbolic Computation · Computer Science 2015-07-07 Jean-Guillaume Dumas , Erich Kaltofen , Emmanuel Thomé

We consider N=4 SYM and a class of spin N, length-3, twist operators beyond the well studied sl(2) subsector. They can be identified at one-loop with three gluon operators. At strong coupling, they are associated with spinning strings with…

High Energy Physics - Theory · Physics 2011-06-20 Matteo Beccaria , Guido Macorini , CarloAlberto Ratti

We consider the problem of approximating the von Neumann entropy of a large, sparse, symmetric positive semidefinite matrix $A$, defined as $\operatorname{tr}(f(A))$ where $f(x)=-x\log x$. After establishing some useful properties of this…

Numerical Analysis · Mathematics 2023-06-23 Michele Benzi , Michele Rinelli , Igor Simunec

The classical Newtonian potentials, defined in terms of metrics, give rise to the basic family of kernels defining linear integral operators and posing the fundamental problems of linear harmonic analysis. When the binary character of a…

Classical Analysis and ODEs · Mathematics 2026-02-03 Hugo Aimar , Ivana Gómez , Joaquín Toledo

It is well known that for general linear systems, only optimal Krylov methods with long recurrences exist. For special classes of linear systems it is possible to find optimal Krylov methods with short recurrences. In this paper we consider…

Numerical Analysis · Mathematics 2023-04-11 R. Idema , C. Vuik

A non-hermitian deformation of the one-dimensional transverse Ising model is shown to have the property of quasi-hermiticity. The transverse Ising chain is obtained from the starting non-hermitian Hamiltonian through a similarity…

Statistical Mechanics · Physics 2009-11-09 Tetsuo Deguchi , Pijush K. Ghosh

We prove a version of symmetric criticality for ropelength-critical knots. Our theorem implies that a knot or link with a symmetric representative has a ropelength-critical configuration with the same symmetry. We use this to construct new…

Differential Geometry · Mathematics 2012-12-21 Jason Cantarella , Jennifer Ellis , Joseph H. G. Fu , Matt Mastin

We study almost Hermitian structures admitting a Hermitian connexion with totally skew-symmetric torsion or equivalently, those almost Hermitian structures with totally skew-symmetric Nijenhuis tensor. We investigate up to what extent the…

Differential Geometry · Mathematics 2007-09-11 Paul-Andi Nagy

We give a numerical criterion for the Nielsen realization problem for Enriques manifolds, based on the recent developments on the Birman-Hilden theory for hyper-K\"ahler manifolds and on Nielsen realization for hyper-K\"ahler manifolds. We…

Algebraic Geometry · Mathematics 2026-04-07 Simone Billi

We study the almost Kaehler geometry of adjoint orbits of non-compact real semisimple Lie groups endowed with the Kirillov-Kostant-Souriau symplectic form and a canonically defined almost complex structure. We give explicit formulas for the…

Differential Geometry · Mathematics 2018-11-27 Alberto Della Vedova , Alice Gatti

Low-precision computing is essential for efficiently utilizing memory bandwidth and computing cores. While many mixed-precision algorithms have been developed for iterative sparse linear solvers, effectively leveraging half-precision (fp16)…

Numerical Analysis · Mathematics 2025-05-28 Kengo Suzuki , Takeshi Iwashita

Continuing the previous initiatives arXiv: 2207.05347 and arXiv: 2212.06180, we pursue the exploration of operator growth and Krylov complexity in dissipative open quantum systems. In this paper, we resort to the bi-Lanczos algorithm…

Quantum Physics · Physics 2023-12-15 Aranya Bhattacharya , Pratik Nandy , Pingal Pratyush Nath , Himanshu Sahu

We study $\mathcal{N}=2$ supersymmetric Sachdev-Ye-Kitaev (SYK) models with complex fermions at non-zero background charge. Motivated by multi-charge supersymmetric black holes, we propose a new $\mathcal{N}=2$ SYK model with multiple…

High Energy Physics - Theory · Physics 2023-02-08 Matthew Heydeman , Gustavo J. Turiaci , Wenli Zhao

One often wishes for the ability to formally analyze large-scale systems---typically, however, one can either formally analyze a rather small system or informally analyze a large-scale system. This work tries to further close this…

Numerical Analysis · Mathematics 2020-08-06 Matthias Althoff

The solution of sequences of shifted linear systems is a classic problem in numerical linear algebra, and a variety of efficient methods have been proposed over the years. Nevertheless, there still exist challenging scenarios witnessing a…

Numerical Analysis · Mathematics 2026-01-28 Hussam Al Daas , Davide Palitta