On the Representation of Data Types

Representations of data types are presented, independently of the specification method used, by means of a generalization of the derivor concept, in a way that permits handling iteration and/or recursion, without losing the property of being closed under composition. The representation correctness is presented in terms of a commutative diagram, which permits to avoid the use of representation invariants. Also, a new concept of restricted representation is presented to deal with situations such as the implementation of a stack by a bounded array.