Lie groups

Circle group

In mathematics, the circle group, denoted by or , is the multiplicative group of all complex numbers with absolute value 1, that is, the unit circle in the complex plane or simply the unit complex numbers The circle group forms a subgroup of , the multiplicative group of all nonzero complex numbers. Since is abelian, it follows that is as well. A unit complex number in the circle group represents a rotation of the complex plane about the origin and can be parametrized by the angle measure : This is the exponential map for the circle group. The circle group plays a central role in Pontryagin duality and in the theory of Lie groups. The notation for the circle group stems from the fact that, with the standard topology (see below), the circle group is a 1-torus. More generally, (the direct product of with itself times) is geometrically an -torus. The circle group is isomorphic to the special orthogonal group . (Wikipedia).

Circle group
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From playlist Abstract algebra

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Now that we know what a quotient group is, let's take a look at an example to cement our understanding of the concepts involved.

From playlist Abstract algebra

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From playlist Modern Algebra - Chapter 15 (groups)

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Please Subscribe here, thank you!!! https://goo.gl/JQ8Nys Group Theory: The Center of a Group G is a Subgroup of G Proof

From playlist Abstract Algebra

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From playlist Abstract Algebra

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This is lecture 5 of an online mathematics course on group theory. It classifies groups of order 4 and gives several examples of products of groups.

From playlist Group theory

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From playlist Abstract Algebra

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From playlist Abstract Algebra

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From playlist Abstract Algebra

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From playlist My Collaborators

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From playlist Algebraic topology

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From playlist Mathematics

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From playlist Mathematics

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From playlist Analysis and Beyond

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From playlist Algebraic topology

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From playlist Number Theory

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From playlist Abstract algebra

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Hua Luogeng | Multiplicative group | Group representation | Lie group | Natural topology | Absolute value | Pontryagin duality | Vector space | Character group | Unitary group | Divisible group | Group of rational points on the unit circle | Symmetry | Exponential map (Lie theory) | Topological group | Up to | Torsion subgroup | Root of unity | Prüfer group | One-parameter group | Group isomorphism | Cardinality of the continuum | Trivial representation | Determinant | Exponential function | Rotation number | Spontaneous symmetry breaking | Quotient group | Direct limit | Euler's formula | Torus | Direct product of groups | Radian | Complex plane | Schur's lemma | Natural number | Connected space | Mathematics | Modular arithmetic | Integer | Unit circle | Rotational invariance | Real number | Cyclic group | N-sphere | Unitary matrix | Solenoid (mathematics) | Compact space | Manifold | Subgroup | Analytic function | Complex number | Character (mathematics) | Group homomorphism | Orthogonal group | Phase factor | Matrix (mathematics) | Irreducible representation | Abelian group | Rotation (mathematics) | Closed set