Diffeomorphic to the 3 sphere.
- Unitary group | 82, 155, 3
- Important Lie groups | 0, 693, 13
- Lie group | 217, 1k, 21
- Important mathematical groups | 0, 1k, 27
- Group | 0, 3k, 50
- Algebra | 0, 3k, 73
- Mathematics | 17, 10k, 260
- Ciro Santilli's Homepage | 238, 154k, 2k
- 3-sphere | 11