A complex Lie group is a complex manifold whose multiplication and inversion are holomorphic maps between complex manifolds. Its tangent space at the identity is a complex Lie algebra; the Adjoint representation of a Lie group and the Lie exponential map are holomorphic. Compatibility with a complex manifold structure is essential: an arbitrary even-dimensional real Lie group need not have holomorphic multiplication.
Every scalar holomorphic function on a compact connected complex manifold is constant by the maximum modulus principle. Apply this to each entry of the holomorphic Adjoint representation of a Lie group; its value is constantly the identity. Differentiation makes the complex Lie algebra abelian, hence connectedness makes the group abelian. The holomorphic Lie exponential map identifies it with modulo a discrete subgroup. Compactness forces that subgroup to span the underlying real vector space, giving a full-rank Euclidean lattice and a complex torus.
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A **complex Lie group** is a mathematical structure that combines the concepts of Lie groups and complex analysis. Specifically, a complex Lie group is a group that is both a smooth manifold and a complex manifold, equipped with a group operation that is compatible with both the manifold structures. Here are some key points to understand complex Lie groups: 1. **Lie Groups**: A Lie group is a group that is also a differentiable manifold, meaning it has a layer of smoothness (i.e.