Expressiveness and Parsimony in Z

There are a number of commonly-used Z operations that may be paired oo. Such pairings include (1) the domain and range operations, (2) domain and range restriction, and (3) domain and range anti-restriction. Not only are the operations within each pair very closely related in terms of what they do, they also give rise to a number of very similar laws. Ockham's razor (or the Law of Parsimony) suggests that we should try to avoid unnecessary duplication. This may be achieved in the way shown in the paper. Furthermore, we can use this approach to make speciications more immediately readable.