## Retrenchment: Extending the Reach of Refinement

Citations: | 11 - 8 self |

### BibTeX

@MISC{Poppleton_retrenchment:extending,

author = {M. R. Poppleton and R. H. Banach},

title = {Retrenchment: Extending the Reach of Refinement },

year = {}

}

### Years of Citing Articles

### OpenURL

### Abstract

Discussion of a simple example demonstrates various expressive limitations of the refinement calculus, and suggests a liberalization of refinement, called retrenchment, which will support an analogous formal development calculus. Useful concrete system behaviour can be specified outside the domain of pure refinement, and a case is made for fluidity between I/O and state components across the development step. A syntax and a formal definition are presented for retrenchment, which has some necessary properties for a formal development calculus: transitivity gives stepwise composition of retrenchments, and monotonicity w.r.t. the specification language constructors gives piecewise construction of retrenchments.