reserve x,y for set,
  k,n for Nat,
  i for Integer,
  G for Group,
  a,b,c ,d,e for Element of G,
  A,B,C,D for Subset of G,
  H,H1,H2,H3,H4 for Subgroup of G ,
  N1,N2 for normal Subgroup of G,
  F,F1,F2 for FinSequence of the carrier of G,
  I,I1,I2 for FinSequence of INT;

theorem Th74:
  for G being strict Group, a,b be Element of G holds [.a,b.] in G `
proof
  let G be strict Group, a,b be Element of G;
  a in (Omega).G & b in (Omega).G by STRUCT_0:def 5;
  hence thesis by Th65;
end;
