   </ol>
        
    
      <b>Tie-breaking</b>
      <br><br>

 The purpose of tie-breaking is to automatically resolve situations
 where the evaluation point <tt>x</tt> is contained in multiple polyhedra. With
 tie-breaking enabled <tt>PolyUnion/feval()</tt> evaluates the tie-breaking function
 to decide which polyhedron containing <tt>x</tt> should be used for evaluation of
 the original function.
 
 The tie-breaking function can be specified by <tt>U.feval(x, 'tiebreak',
 tb_fun)</tt>, where <tt>tb_fun