Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Topological invariants displayed as Betti numbers. Betti-0 represents the number of connected components, Betti-1 the number of tunnels or circles, and Betti-2 the number of cavities or voids. Two auxiliary rings are added to the torus to illustrate that its Betti-1=2.
 |
||||
|---|---|---|---|---|
| Example | Point | Circle | Sphere | Torus |
| Betti-0 | 1 | 1 | 1 | 1 |
| Betti-1 | 0 | 1 | 0 | 2 |
| Betti-2 | 0 | 0 | 1 | 1 |
