منابع مشابه
Combinatorial Harmonic Maps and Discrete-group Actions on Hadamard Spaces
A harmonic map between two Riemannian manifolds is defined to be a critical point of the energy functional; the energy of a smooth map is by definition the integration of the squared norm of its differential over the source manifold. By solving the heat equation associated with the energy functional, Eells and Sampson [7] proved that if two manifolds are compact and the target has nonpositive s...
متن کاملstudy 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 Maps from Loop Suspensions to Loop Spaces and the Shuffle Relations on the Cohen Groups
The maps from loop suspensions to loop spaces are investigated using group representations in this article. The shuffle relations on the Cohen groups are given. By using these relations, a universal ring for functorial self maps of double loop spaces of double suspensions is given. Moreover the obstructions to the classical exponent problem in homotopy theory are displayed in the extension grou...
متن کاملLectures on Harmonic Maps
§1 Background and Setup Let M be an m-dimensional, compact, Riemannian manifold endowed with the metric dsM = gij dx i dx , where {x, x, · · · , x} is a local coordinate system of M. Suppose N is an n-dimensional, complete, Riemannian manifold with metric given by dsN = hαβ du α du , where {u, u, · · · , u} is a local coordinate system of N. Let f : M → N be a C mapping from M into N . Definiti...
متن کاملOn Homotopic Harmonic Maps
(1.1) M' is complete and its sectional curvatures are non-positive. In terms of local coordinates x = (x, . . . , x) on M and y = (y, . . . , y) on M', let the respective Riemann elements of arc-length be ds = gij dx dx\ ds' = g'a$ dy a dy& and r^-fc, T'Vy be the corresponding Christoffel symbols. When there is no danger of confusion, x (or y) will represent a point of M (or M') or its coordina...
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ژورنال
عنوان ژورنال: Transactions of the American Mathematical Society
سال: 1991
ISSN: 0002-9947
DOI: 10.2307/2001786