Computer science

Specification explosion

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To verify software, we must specify it; otherwise there is nothing to verify against. People often cite the burden of specification as the major obstacle toward making verification practical. At issue are not only the effort required to express the goals of software elements (their contracts) but also intermediate assertions, or “verification conditions”, including loop … Read more




Towards a Calculus of Object Programs

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I posted here a draft of a new article, Towards a Calculus of Object Programs. Here is the abstract: Verifying properties of object-oriented software requires a method for handling references in a simple and intuitive way, closely related to how O-O programmers reason about their programs. The method presented here, a Calculus of Object Programs, … Read more




Agile methods: the good, the bad and the ugly

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Agile methods are wonderful. They’ll give you software in no time at all, turn your customers and users into friends, catch bugs before they catch you, change the world, and boost your love life.







Assessing concurrency models

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In a recent experiment with students we wanted to know how the SCOOP concurrency model compares to Java Threads in terms of ease of learning, program readability and correctness. Our group, however, is heavily involved with SCOOP. How did we address the risk of bias, and other parts of the “Professor Smith Syndrome”? What are our results, and can you believe them?







In praise of Knuth and Liskov

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Youth has its advantages; perhaps the most striking is that we can, in our own lifetime, meet in person some of the very founders of our discipline. No living physicist has seen Newton; no chemist has heard Lavoisier. For us, it works. Today, Ladies and Gentlemen, we have the honor of introducing two of the undisputed pioneers of informatics.







Publish no loop without its invariant

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There may be no more blatant example of the disconnect between the software engineering community and the practice of programming than the lack of widespread recognition for the fundamental role of loop invariants.