In section 4 we give an interpretation of the types of our systems as monotone operators on value sets.
Note that complex widening operators, such as the ones that will be presented in the following sections, will not generally be stable.
A typical solution is to add new operators to the abstract interface for freeing of abstract objects.
Most languages support some kind of overloading of operators, also known as ad hoc polymorphism.
The other functions and operators are also shown here because of their use in the transformation process.
In functional programming, catamorphisms are what are known as fold operators.
Using these operators, we were able to either incorporate or not incorporate each of these four constraints independently.
The usefulness of the operators designed in the first experiment could then be evaluated with a more difficult design problem and related scalability issues investigated.
