The second half of the twentieth century saw an astonishing increase in computing power; today computers are unbelievably faster than they used to be, they have more memory, they can communicate routinely with remote machines all over the world - and they can fit on a desktop. But, despite this remarkable progress, the voracity of modem applications and user expectations still pushes technology right to the limit. As hardware engineers build ever-more-powerful machines, so too must software become more sophisticated to keep up. Medium- to large-scale programming projects need teams of people to pull everything together in an acceptable timescale. The question of how pro gram­ mers understand their own tasks, and how they fit together with those of their colleagues to achieve the overall goal, is a major concern. Without that under­ standing it would be practically impossible to realise the commercial potential of our present-day computing hardware. That programming has been able to keep pace with the formidable advances in hardware is due to the similarly formidable advances in the principles for design, construction and organisation of programs. The efficacy of these methods and principles speaks for itself - computer technology is all-pervasive - but even more telling is that they are beginning to feed back and inftuence hardware design as weIl. The study of such methods is called programming methodology, whose topics range over system-and domain-modelling, concurrency, object orientation, program specification and validation. That is the theme of this collection.

I Models and correctness.- A Concurrency and interaction.- 1 Wanted: a compositional approach to concurrency.- 2 Enforcing behavior with contracts.- B Logical approaches to asynchrony.- 3 Asynchronous progress.- 4 A reduction theorem for concurrent object-oriented programs.- C Systems and real time.- 5 Abstractions from time.- 6 A predicative semantics for real-time refinement.- D Specifying complex behaviour.- 7 Aspects of system description.- 8 Modelling architectures for dynamic systems.- 9 "What is a method?" - an essay on some aspects of domain engineering.- II Programming techniques.- E Object orientation.- 10 Object-oriented programming and software development - a critical assessment.- 11 A trace model for pointers and objects.- 12 Object models as heap invariants.- 13 Abstraction dependencies.- F Type theory.- 14 Type systems.- 15 What do types mean? - From intrinsic to extrinsic semantics.- III Applications and automated theories.- G Putting theories into practice by automation.- 16 Automated verification using deduction, exploration, and abstraction.- 17 An experiment in feature engineering.- H Programming circuits.- 18 High-level circuit design.- I Security and keeping secrets.- 19 Power analysis: attacks and countermeasures.- 20 A probabilistic approach to information hiding.