Hidden signatures provide the basic vocabulary for describing a system, including the methods and attributes of its objects, and its data values.

A **hidden signature** (over a data algebra D) is a pair (H,), where
H is a set of **hidden sorts**
disjoint from the set V of **visible sorts**, and is an S = (H V)-sorted signature containing , such
that

- each f in of rank w,s with w in V* and s in V lies in , and
- each f in of rank w,s has at most one element of H in w.

We may abbreviate (H,) to just . If
w in S* contains a
hidden sort, then we call f in of sort s a
**method** if s in H, and an **attribute** if s is in V.

[Next] [Prev] [Home] [BHome]

11 October 1996