By Topic

Lessons from using Z to specify a software tool

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$33 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

4 Author(s)
M. Neil ; Centre for Software Reliability, City Univ., London, UK ; G. Ostrolenk ; M. Tobin ; M. Southworth

The authors were recently involved in the development of a COBOL parser (G. Ostrolenk et al., 1994), specified formally in Z. The type of problem tackled was well suited to a formal language. The specification process was part of a life cycle characterized by the front loading of effort in the specification stage and the inclusion of a statistical testing stage. The specification was found to be error dense and difficult to comprehend. Z was used to specify inappropriate procedural rather than declarative detail. Modularity and style problems in the Z specification made it difficult to review. In this sense, the application of formal methods was not successful. Despite these problems the estimated fault density for the product was 1.3 faults per KLOC, before delivery, which compares favorably with IBM's Cleanroom method. This was achieved, despite the low quality of the Z specification, through meticulous and effort intensive reviews. However, because the faults were in critical locations, the reliability of the product was assessed to be unacceptably low. This demonstrates the necessity of assessing reliability as well as “correctness” during system testing. Overall, the experiences reported in the paper suggest a range of important lessons for anyone contemplating the practical application of formal methods

Published in:

IEEE Transactions on Software Engineering  (Volume:24 ,  Issue: 1 )