Two-sheeted Cover
The 2-torus double-covers the 2-sphere, with four ramification points. Every conformal structure on the 2-torus can be represented as a two-sheeted cover of the 2-sphere. The points on the torus corresponding to the ramification points are the Weierstrass points. In fact, the conformal type of the torus is determined by the cross-ratio of the four points.
Read more about this topic: Torus
Famous quotes containing the word cover:
“There is reason in the distinction of civil and uncivil. The manners are sometimes so rough a rind that we doubt whether they cover any core or sap-wood at all.”
—Henry David Thoreau (1817–1862)