 reserve m,n for Nat;
 reserve i,j for Integer;
 reserve S for non empty multMagma;
 reserve r,r1,r2,s,s1,s2,t for Element of S;
 reserve G for Group-like non empty multMagma;
 reserve e,h for Element of G;
 reserve G for Group;
 reserve f,g,h for Element of G;

theorem
  h * g = h or g * h = h implies g = 1_G
proof
  h * 1_G = h & 1_G * h = h by Def4;
  hence thesis by Th6;
end;
