 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 Th35: :: Theorem 3.5
  Tern (a,b,a`) = b
  proof
    Tern (a,b,a`) = Tern (a,b,Tern (b,a`,a`)) by TRIDef
                 .= Tern (Tern(a,b,b), a`, Tern (a,b,a`)) by TDis
                 .= Tern (b, a`, Tern (a,b,a`)) by TRIDef
                 .= Tern (Tern(b,a`,a),b, Tern (b,a`,a`)) by TDis
                 .= Tern (Tern(b,a`,a``),b, Tern (b,a`,a`)) by Lemma0
                 .= Tern (b, b, Tern (b,a`,a`)) by TRADef
                 .= b by TLIDef;
    hence thesis;
  end;
