 reserve T for Ternary_Boolean_Algebra;
 reserve a,b,c,d,e for Element of T;
 reserve x,y,z for Element of T;

theorem Th32: :: Theorem 3.2
  Tern (a,b,a) = a
  proof
    Tern (a,b,a) = Tern (Tern (a,b,b`),b,a) by TRADef
                .= Tern (Tern (a,b,b`),b,Tern (a,b,b`)) by TRADef
                .= Tern (a,b,Tern(b`,b,b`)) by TDis
                .= Tern (a,b,b`) by TLADef
                .= a by TRADef;
    hence thesis;
  end;
