code: @Override
      public double compute(double a, double b) {
          if (Op.isLt(a + b, 1.0)) {
              return Op.max(a, b);
          }
          return 1.0;
      }
docs: Computes the nilpotent maximum of two membership function values
  
  @param a is a membership function value
  @param b is a membership function value
  @return `\begin{cases} \max(a,b) & \mbox{if $a+b<0$} \cr 1 &
  \mbox{otherwise} \end{cases}`