منابع مشابه
study of hash functions based on chaotic maps
توابع درهم نقش بسیار مهم در سیستم های رمزنگاری و پروتکل های امنیتی دارند. در سیستم های رمزنگاری برای دستیابی به احراز درستی و اصالت داده دو روش مورد استفاده قرار می گیرند که عبارتند از توابع رمزنگاری کلیددار و توابع درهم ساز. توابع درهم ساز، توابعی هستند که هر متن با طول دلخواه را به دنباله ای با طول ثابت تبدیل می کنند. از جمله پرکاربردترین و معروف ترین توابع درهم می توان توابع درهم ساز md4, md...
On Factorizations of Maps between Curves
We examine the different ways of writing a cover of curves φ : C → D over a field K as a composition φ = φn ◦ φn−1 ◦ · · · ◦ φ1, where each φi is a cover of curves over K of degree at least 2 which cannot be written as the composition of two lower-degree covers. We show that if the monodromy group Mon(φ) has a transitive abelian subgroup then the sequence (deg φi)1≤i≤n is uniquely determined up...
متن کاملFiltrations, Factorizations and Explicit Formulae for Harmonic Maps
We use filtrations of the Grassmannian model to produce explicit algebraic formulae for harmonic maps of finite uniton number from a Riemann surface to the unitary group for a general class of factorizations by unitons. We show how these specialize to give explicit formulae for harmonic maps into the special orthogonal and symplectic groups, real, complex and quaternionic Grassmannians, and the...
متن کاملScalable Parallel Factorizations of SDD Matrices and Efficient Sampling for Gaussian Graphical Models
Motivated by a sampling problem basic to computational statistical inference, we develop a nearly optimal algorithm for a fundamental problem in spectral graph theory and numerical analysis. Given an n × n SDDM matrix M, and a constant −1 ≤ p ≤ 1, our algorithm gives efficient access to a sparse n× n linear operator C̃ such that M p ≈ C̃C̃ ⊤ . The solution is based on factoring M into a product of...
متن کاملModel-Driven Generation of Graphical Maps for e-Contents
In this paper we present the application of a model driven software development approach (MDSD) to the generation of graphical (interactive) maps. The approach is rooted on the Eclipse Modeling Framework (EMF) and on a textual representation of the metamodel handled by the openArchitectureWare (oAW) suite of plug-ins. The metamodel represents our domain-specific language (DSL), which extends th...
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ژورنال
عنوان ژورنال: Homology, Homotopy and Applications
سال: 2018
ISSN: 1532-0073,1532-0081
DOI: 10.4310/hha.2018.v20.n2.a11