public void AddHidden(CompoundFormula cf)
        {
            Domain.AddHidden(cf);

            /*
             * if (cf.Operator == "oneof")
             * {
             *  CompoundFormula cfOr = new CompoundFormula("or");
             *  for (int j = 0; j < cf.Operands.Count; j++)
             *  {
             *      CompoundFormula cfAnd = new CompoundFormula("and");
             *      cfAnd.AddOperand(cf.Operands[j]);
             *      for (int i = 0; i < cf.Operands.Count; i++)
             *      {
             *          if (i != j)
             *              cfAnd.AddOperand(cf.Operands[i].Negate());
             *      }
             *      cfOr.AddOperand(cfAnd.Simplify());
             *  }
             *  m_lHidden.Add(cfOr);
             * }
             * else
             *  m_lHidden.Add(cf);
             * */
            m_lHidden.Add(cf);
        }