San Francisco Health Care Security Ordinance & its intersection with the Health Care Accountability Ordinance Joannie C. Chang Office of Labor Standards Enforcement City & County of San Francisco January 2009.
In geometry, a torus (plural tori) is a surface of revolution generated by revolving a circle in three-dimensional space about an axis coplanar with the circle.he flat torus is a torus with the metric inherited from its representation as the quotient, R 2 / L, where L is a discrete subgroup of R 2 isomorphic to Z 2. This gives the quotient the structure of a Riemannian manifold.
The key to understanding the KAM theorem is the concept of an invariant torus. A torus is the surface of an inner tube, a bagel, or a doughnut. Any point on the torus can be labelled by two angles. one giving the angle around the hole in the middle and the other giving the angle around the tube cylinder.