Proving SL_2(C) Homeomorphic to SU(2)xT & Simple Connectedness

In summary, the conversation discusses the QR decomposition and its use in proving that SL(2,C) is homeomorphic to the product SU(2) × T, where T is the set of upper-triangular 2×2-complex matrices with real positive entries at the diagonal. This also implies that SL(2,C) is simply-connected. The conversation also mentions a map between SU(2) × T and SL(2,C) and its injectivity and surjectivity, as well as the continuity of this map and its inverse. The use of determinant in this map is also mentioned.
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aalma
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Using the QR decomposition (the complex version) I want to prove that ##SL_2(C)## is homeomorphic to the product ##SU(2) × T## where ##T## is the set of upper-triangular 2×2-complex matrices with real positive entries at the diagonal. Deduce that ##SL(2, C)## is simply-connect.

So, I can define a map ##SU(2)×T–>SL(2,C)## given by: ##(u,t) –> ut## where ##u \in SU(2)## and ##t \in T## (from QR decomposition we have that each ##A## in ##GL(2,C)## can be written as ##ut## where ##u \in U(n)## and ##t \in T## (##T## mentioned above)).
We have that the intersection ##SU(2)\cap T=1##.
This map is injective:
if ##u_1t_1=u_2t_2## then this gives
##u_2^{-1}u_1=t_2t_1^{-1} \in SU(2)\cap T## so ##u_1=u_2## and ##t_1=t_2##.
Can I say that this map is surjective by the QR decomposition?
why is this map and its inverse contiuous?

Thanks for help!
 
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1. What is SL_2(C)?

SL_2(C) is a mathematical group consisting of 2x2 complex matrices with a determinant of 1. It stands for "special linear group of degree 2 over the complex numbers."

2. What is SU(2)?

SU(2) is a mathematical group consisting of 2x2 unitary matrices with a determinant of 1. It stands for "special unitary group of degree 2."

3. What is T in the equation SU(2)xT?

T represents the group of complex numbers with absolute value 1. It is also known as the circle group or the unitary group of degree 1.

4. How do you prove that SL_2(C) is homeomorphic to SU(2)xT?

To prove that two groups are homeomorphic, one must show that there exists a continuous bijective function between the two groups. In this case, the function is given by the map f: SL_2(C) -> SU(2)xT, where f(A) = (B, det(A)/|det(A)|), where B is the upper left 2x2 submatrix of A. This function is continuous, bijective, and has a continuous inverse, thus proving the homeomorphism.

5. Why is proving simple connectedness important in this context?

Proving simple connectedness is important because it ensures that the two groups, SL_2(C) and SU(2)xT, are not only homeomorphic, but also topologically equivalent. This means that not only do they have the same shape, but also the same properties, such as being simply connected. This is an important concept in mathematics and has implications in various fields, such as topology, geometry, and physics.

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