reserve x,y,y1,y2 for set;
reserve G for Group;
reserve a,b,c,d,g,h for Element of G;
reserve A,B,C,D for Subset of G;
reserve H,H1,H2,H3 for Subgroup of G;
reserve n for Nat;
reserve i for Integer;
reserve L for Subset of Subgroups G;

theorem Th109:
  for H being strict Subgroup of G holds H in con_class H
proof
  let H be strict Subgroup of G;
  H,H are_conjugated;
  hence thesis by Def12;
end;
