On software quality and engineering

[Doug.Palmer at csiro.au]

> Now, can anyone give me the ISBN for a good reference or 
> tutorial book 
> on Z formal proof?

There's an online book "Using Z" http://softeng.comlab.ox.ac.uk/usingz/ I
don't know about good, but it's comprehensible to me at least and contains a
number of examples of using proofs. It's 4-5Mb in PDF form, so beware.

There's also a nice quote, which seems appropriate to this discussion, from
the Z Book, http://www.afm.sbu.ac.uk/zbook/ 

"Of course, there is no fool-proof methodology or magic formula that will
ensure a good, efficient, or even feasible design. For that, the designer
needs experience, insight, flair, judgement, invention. Formal methods can
only stimulate, guide, and discipline our human inspiration, clarify design
alternatives, assist in exploring their consequences, formalize and
communicate design decisions, and help to ensure that they are correctly
carried out."

-- C.A.R. Hoare, 1988