public static int GetIndex(PDLLogicalOperator op)
        {
            switch (op)
            {
            case PDLLogicalOperator.And: return(0);

            case PDLLogicalOperator.If: return(1);

            case PDLLogicalOperator.Iff: return(2);

            case PDLLogicalOperator.Or: return(3);

            default: throw new PDLException("undefined operator");
            }
        }
 public static bool IsSymmetric(PDLLogicalOperator op)
 {
     return op != PDLLogicalOperator.If;
 }
 public static int GetIndex(PDLLogicalOperator op)
 {
     switch (op)
     {
         case PDLLogicalOperator.And: return 0;
         case PDLLogicalOperator.If: return 1;
         case PDLLogicalOperator.Iff: return 2;
         case PDLLogicalOperator.Or: return 3;
         default: throw new PDLException("undefined operator");
     }
 }
 public CPDLLogConnPred(CPDLPred lhs, CPDLPred rhs, PDLLogicalOperator original) {
     this.lhs = lhs;
     this.rhs = rhs;
     this.original = original;
 }
 public static bool IsSymmetric(PDLLogicalOperator op)
 {
     return(op != PDLLogicalOperator.If);
 }