1. A computer program product, tangibly embodied in a machine-readable storage device, the computer program product comprising instructions operative to cause data processing apparatus to: normalize a first value of a partition vector, a last value of the partition vector, or both the first minimum and maximum values of the partition vector of a first set object in accordance with a first process to produce a normalized version of the first set object, the partition vector comprising ordered values from the first value to the last value and further comprising a set of knot values ordered from a first knot value to a last knot value, wherein: normalizing the first value comprises keeping the first value or removing the first value to make a second value of the partition vector the first value when the first knot value of the partition vector is a second minimum value of a universal set object corresponding to the first set object, the second minimum value being both a minimum value supported by a data type and defined to be in the universal set object; and normalizing the last value comprises keeping the last value or removing the last value to make a penultimate value of the partition vector the last value when the last knot value of the partition vector is a second maximum value of the universal set object, the second maximum value being both a maximum value supported by a data type and defined to be in the universal set object; and perform a set operation on the normalized version of the first set object to generate a result, wherein, the normalized version of the first set object has the normalized first value, the normalized last value, or both the normalized first and normalized last values normalized in accordance with the first process.