WELCOME TO THE [original] PSL/PSA HOME PAGE [click here for the new Home Page]

Problem Statement Language (PSL) and Problem Statement Analyzer (PSA), usually referred to as PSL/PSA, are the oldest tools to support requirements modelling and analysis using the object property relationship approach that is still valid (see History) and has not yet been replaced by anything else more suitable.

PSL/PSA modelling is an entirely linguistic technique - it is completely scalable and has been used on some huge projects. Specifications can be analyzed for completeness, correctness, and consistency. Structured techniques and the Unified Modelling Language (UML) perform much less satisfactorily than PSL/PSA. PSL/PSA is entirely neutral with respect to the debate between structured and object-oriented techniques, which can both be modelled with subsets of PSL.

Why was PSL/PSA not widely adopted? After all, at one time, it was in the price book of large companies such as IBM and Digital Equipment Corporation (DEC). There were four key problems: (1) commercialization - this should never have been attempted - it should have remained a research program - after commercialization, the contribution of many eminent organizations and corporations dried up (2) cost - the cost per PSL/PSA licence was $45,000 plus similar sums for the necesary add-on tools (3) the underlying implementation technology did not keep up with emerging technological trends (4) the language PSL and key research documents should have been in the public domain.

It is time to breath life back into PSL/PSA. That is now happening. Daniel Teichroew and I were working on putting the PSL langauge into the public domain when he died. The project is continuing, and PSL will be published here during 2005-7. Discussions are under way for a new research project. Additional material will be published here, including some key research material, commentary, and updated text of PSL/PSA manuals. Some organizations are working to bring out new versions of PSL/PSA and related products.

Geoffrey Darnton, August 2007.

A New Home page is under development - click here to be transferred - there will be some duplication of content until transfer is complete