
 PlanetMath: group 
  Groups often arise as the symmetry groups of other mathematical objects; the study of such situations uses group actions. 
  See Also: subgroup, cyclic group, simple group, symmetric group, free group, ring, field, group homomorphism, Lagrange's theorem, identity element, proper subgroup, groupoid, fundamental group, topological group (obsolete), Lie group, Proof: The orbit of any element of a group is a subgroup, locally cyclic group, existence of Hilbert class field, abelian group, 
  This is version 17 of group, born on 20010829, modified 20060314. 
 planetmath.org /encyclopedia/Group.html (314 words) 
