code: @Override
      public double compute(double a, double b) {
          return (a * b) / (2 - (a + b - a * b));
      }
docs: Computes the Einstein product of two membership function values
  
  @param a is a membership function value
  @param b is a membership function value
  @return `(a\times b)/(2-(a+b-a\times b))`