X-Nico

unusual facts about quotient group



Link group

The link group of the Hopf link, the simplest non-trivial link – two circles, linked once – is the free abelian group on two generators, \mathbf{Z}^2. Note that the link group of two unlinked circles is the free nonabelian group on two generators, of which the free abelian group on two generators is a quotient.


see also