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The uniformization theorem for surfaces states that the upper half-plane is the universal covering space of surfaces with constant negative Gaussian curvature. The closed upper half-plane is the union of the upper half-plane and the real axis. It is the closure of the upper half-plane.
A half-space can be either open or closed. An open half-space is either of the two open sets produced by the subtraction of a hyperplane from the affine space. A closed half-space is the union of an open half-space and the hyperplane that defines it. The open (closed) upper half-space is the half-space of all (x 1, x 2, ..., x n) such that x n > 0
For an analytic function in the upper half-plane, the Hilbert transform describes the relationship between the real part and the imaginary part of the boundary values. That is, if f ( z ) is analytic in the upper half complex plane { z : Im{ z } > 0} , and u ( t ) = Re{ f ( t + 0· i )} , then Im{ f ( t + 0· i )} = H( u )( t ) up to an ...
Two points in the upper half-plane give isomorphic elliptic curves if and only if they are related by a transformation in the modular group. Thus, the quotient of the upper half-plane by the action of the modular group is the so-called moduli space of elliptic curves: a space whose points describe isomorphism classes of elliptic curves. This is ...
If a proper metric is introduced, the upper half-plane becomes a model of the hyperbolic plane H 2, the Poincaré half-plane model, and PSL(2, R) is the group of all orientation-preserving isometries of H 2 in this model.
The metric of the model on the half-plane, { , >}, is: = + ()where s measures the length along a (possibly curved) line. The straight lines in the hyperbolic plane (geodesics for this metric tensor, i.e., curves which minimize the distance) are represented in this model by circular arcs perpendicular to the x-axis (half-circles whose centers are on the x-axis) and straight vertical rays ...
Cayley transform of upper complex half-plane to unit disk. On the upper half of the complex plane, the Cayley transform is: [1] [2] = +.Since {,,} is mapped to {,,}, and Möbius transformations permute the generalised circles in the complex plane, maps the real line to the unit circle.
In complex analysis, the Hardy spaces (or Hardy classes) are spaces of holomorphic functions on the unit disk or upper half plane.They were introduced by Frigyes Riesz (), who named them after G. H. Hardy, because of the paper ().