Constructing an Analytic Mapping for SL(2;R) using Quadratic Forms

In summary, the conversation discusses the construction of an analytic mapping \phi(x,y) for the H^{2+} \times S^1 representation of the group SL(2;R). This involves parametrizing the group as x=[x y \theta] and finding a matrix representation for the quadratic form z^2 -x^2 -y^2=1 in R^3. The goal is to calculate the matrix representation for g(x) \in SL(2;R) by multiplying the matrix for the quadratic form and the rotation matrix for S^1. The challenge is finding a parametrized quadratic form for H^2. The specific mapping \phi is not specified in terms of real or complex analytic.
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Homework Statement


Construct the analytic mapping [tex]\phi(x,y)[/tex] for the [tex]H^{2+} \times S^1[/tex] representation of [tex]SL(2;R)[/tex]


Homework Equations


[tex]g(x) \circ g(y) = g(\phi(x,y))[/tex]


The Attempt at a Solution


So, all points in SL(2;R) lie on the manifold [tex]H^{2+} \times S^1[/tex]. I also know that SL(2;R) is 3 dimensional, so I will parametrize it as x=[x y [tex]\theta[/tex]].

For a point to lie on [tex]H^{2+}[/tex] it has to satisfy the quadratic form [tex]z^2 -x^2 -y^2=1[/tex] in [tex]R^3[/tex]. I calculated the 3x3 matrix, H, for this quadratic form, which has diagonal [-1 -1 1] and zeros everywhere else.

My goal is to calculate the matrix rep for [tex]g(x) \in SL(2;R) [/tex] by multiplying H and the rotation matrix for [tex]S^1[/tex] which is well known, and then using this information end up solving for [tex]\phi[/tex]

My problem is that H, my matrix for the quadratic form, is not paramaterized by x and y, its elements are just constants. How do I find a quadratic form for [tex]H^2[/tex] that is paramaterized by x and y?
 
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  • #2
The mapping [itex]\phi[/itex] is supposed to be from where to where? Real analytic or complex analytic?
 

1. What is a quadratic form?

A quadratic form is a mathematical expression that can be written in the form of ax^2 + bxy + cy^2, where a, b, and c are constants and x and y are variables. It represents a second-degree polynomial and is used to describe the properties of a quadratic function.

2. What is the significance of SL(2;R) in quadratic forms?

SL(2;R) is a special linear group of 2x2 matrices with real coefficients and a determinant of 1. It is significant in quadratic forms because it represents the group of linear transformations that preserve the quadratic form. In other words, it represents the group of transformations that do not change the shape of the quadratic function.

3. How are quadratic forms used in linear algebra?

Quadratic forms are used in linear algebra to study the properties of quadratic functions and to solve problems involving systems of linear equations. They are also used in optimization and diagonalization of matrices.

4. Can quadratic forms be used in other fields besides mathematics?

Yes, quadratic forms have applications in various fields such as physics, engineering, and computer science. They are used to model physical systems, analyze data, and solve optimization problems.

5. What are some examples of quadratic forms?

Some examples of quadratic forms include the distance formula in geometry, the energy of a vibrating string in physics, and the cost function in economics. They can also be found in real-life applications such as calculating the area of a rectangle or the volume of a cube.

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