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We present and test a code for two-fluid simulations of galaxy formation, one of the fluids being collision-less. The hydrodynamical evolution is solved through the SPH method while gravitational forces are calculated using a tree method.…

Astrophysics · Physics 2007-05-23 John Hultman , Daniel Kaellander

We study locality-sensitive hash methods for the nearest neighbor problem for the angular distance, focusing on the approach of first projecting down onto a low-dimensional subspace, and then partitioning the projected vectors according to…

Data Structures and Algorithms · Computer Science 2020-06-30 Thijs Laarhoven

A construction for sphere packings is introduced that is parallel to the ``anticode'' construction for codes. This provides a simple way to view Vardy's recent 20-dimensional sphere packing, and also produces packings in dimensions 22,…

Combinatorics · Mathematics 2015-06-26 J. H. Conway , N. J. A. Sloane

This paper develops an explicit and implementable framework for constructing spherical designs by lifting point sets from tight fusion frames. By combining existing ingredients, we obtain, in every dimension, explicit spherical $5$-designs…

Combinatorics · Mathematics 2026-02-24 Ryutaro Misawa

We exhibit the first examples of contact structures on $S^{2n-1}$ with $n\geq 4$ and on $S^3\times S^2$, all equipped with their standard smooth structures, for which every Reeb flow has positive topological entropy. As a new technical tool…

Symplectic Geometry · Mathematics 2017-06-21 Marcelo R. R. Alves , Matthias Meiwes

For an effective Cartier divisor D on a scheme X we may form an nth root stack. Its derived category is known to have a semiorthogonal decomposition with components given by D and X. We show that this decomposition is 2n-periodic. For n=2…

Algebraic Geometry · Mathematics 2024-06-04 Agnieszka Bodzenta , Will Donovan

In this paper we report on PD-SPH the new tree-sph code developed in Padua. The main features of the code are described and the results of a new and independent series of 1-D and 3-D tests are shown. The paper is mainly dedicated to the…

Astrophysics · Physics 2009-10-30 Giovanni Carraro , Cesario Lia , Cesare Chiosi

The usual T-duality that relates the type IIA and IIB theories compactified on circles of inversely-related radii does not operate if the dimensional reduction is performed on the time direction rather than a spatial one. This observation…

High Energy Physics - Theory · Physics 2009-10-07 C. N. Pope , A. Sadrzadeh , S. R. Scuro

We present constructions of Space-Time (ST) codes based on lattice coset coding. First, we focus on ST code constructions for the short block-length case, i.e., when the block-length is equal to or slightly larger than the number of…

Information Theory · Computer Science 2008-04-14 K. Raj Kumar , Giuseppe Caire

QR decomposition is used prevalently in wireless communication. In this paper, we express the Givens-rotation-based QR decomposition algorithm on a spatial architecture using T2S (Temporal To Spatial), a high-productivity spatial…

Programming Languages · Computer Science 2018-05-22 Hongbo Rong

Fractional repetition (FR) codes are a family of repair-efficient storage codes that provide exact and uncoded node repair at the minimum bandwidth regenerating point. The advantageous repair properties are achieved by a tailor-made…

Information Theory · Computer Science 2020-05-15 Bing Zhu , Hui Li , Kenneth W. Shum , Shuo-Yen Robert Li

For most aspherical Seifert-fibered 3-manifolds $M$, the space of Seifert fiberings $SF(M)$ is known to have contractible components. It is also known that the space of Hopf fiberings of the three-sphere is noncontractible. We provide the…

Geometric Topology · Mathematics 2024-04-15 Yi Wang , Jingye Yang

We classify nonsingular holomorphic foliations of dimension and codimension one on certain Hopf manifolds. More general, we prove that all nonsingular codimension one distributions on intermediary or generic Hopf manifolds are integrable…

Algebraic Geometry · Mathematics 2018-10-15 Maurício Corrêa , Arturo Fernández-Pérez , Antonio M. Ferreira

In a previous work arXiv:physics/0611108v2, it was shown that the volume spanned by a molecular system in its conformational space can be effectively bounded by a polyhedral cone, this cone is described by means of a simple combinatorial…

Computational Physics · Physics 2007-10-15 Jacques Gabarro-Arpa

The set of all error-correcting codes C over a fixed finite alphabet F of cardinality q determines the set of code points in the unit square with coordinates (R(C), delta (C)):= (relative transmission rate, relative minimal distance). The…

Information Theory · Computer Science 2019-09-04 Yuri I. Manin , Matilde Marcolli

In this article, we construct codes with hierarchical locality using natural geometric structures in Artin-Schreier surfaces of the form $y^p-y=f(x,z)$. Our main theorem describes the codes, their hierarchical structure and recovery…

Number Theory · Mathematics 2024-11-15 Jennifer Berg , Beth Malmskog , Mckenzie West

A Hopf texture is a vacuum field configuration of isovector fields which is an onto map from the space as a large three sphere to the vacuum manifold $S^2$. We construct a Hopf texture with spherically symmetric energy density and discuss…

High Energy Physics - Phenomenology · Physics 2007-05-23 Sun Hong Rhie , David P. Bennett

This Letter outlines 20 geometric mechanisms by which limit cycles are created locally in two-dimensional piecewise-smooth systems of ODEs. These include boundary equilibrium bifurcations of hybrid systems, Filippov systems, and continuous…

Dynamical Systems · Mathematics 2018-08-15 D. J. W. Simpson

Hopfions, higher-dimensional topological quasiparticles with sophisticated 3D knotted spin textures discovered in condensed matter and photonic systems, show promise in high-density data storage and transfer. Here we present crystalline…

Optics · Physics 2025-08-22 Wenbo Lin , Nilo Mata-Cervera , Yasutomo Ota , Yijie Shen , Satoshi Iwamoto

In this paper, we introduce a novel explicit family of subcodes of Reed-Solomon (RS) codes that efficiently achieve list decoding capacity with a constant output list size. Our approach builds upon the idea of large linear subcodes of RS…

Information Theory · Computer Science 2024-01-29 Amit Berman , Yaron Shany , Itzhak Tamo