nLab upper half-plane

Idea

The part of the complex plane of positive imaginary part is often called the upper half plane, sometimes denoted $\mathfrak{H}$.

Accodingly the lower half plane is the subset of complex numbers with negative imaginary part.

Related concepts

• contour integral

• Möbius group

• modular form, automorphic form

• Siegel upper half-space

• moduli space of elliptic curves, moduli space of Riemann surfaces

References

• Wikipedia, Upper half plane