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2008 Turing Award Winners Announced 66

The Association for Computing Machinery has announced the 2008 Turing Award Winners. Edmund M. Clarke, Allen Emerson, and Joseph Sifakis received the award for their work on an automated method for finding design errors in computer hardware and software. "Model Checking is a type of "formal verification" that analyzes the logic underlying a design, much as a mathematician uses a proof to determine that a theorem is correct. Far from hit or miss, Model Checking considers every possible state of a hardware or software design and determines if it is consistent with the designer's specifications. Clarke and Emerson originated the idea of Model Checking at Harvard in 1981. They developed a theoretical technique for determining whether an abstract model of a hardware or software design satisfies a formal specification, given as a formula in Temporal Logic, a notation for describing possible sequences of events. Moreover, when the system fails the specification, it could identify a counterexample to show the source of the problem. Numerous model checking systems have been implemented, such as Spin at Bell Labs."
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2008 Turing Award Winners Announced

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  • by Bozdune ( 68800 ) on Monday February 04, 2008 @07:40PM (#22300014)
    This is precisely the problem with such ideas. As you said, if a program is sufficiently rigorously specified that an automated proof-of-correctness can be generated, then the specification of the program is obviously complex enough to require that it, too, must undergo testing to ensure that it is correct, and so on. We might end up with 2 = 2, but that doesn't help much if we wanted 3.

    The DoD has funded these efforts heavily since the 1970's, and computer science graduate students have been all over them for as long as I can remember. I've read way too many dull papers on the topic, as one amateur modern algebraist after another discovers the wonders of Hoare and rushes into print with his or her "unique" twist, all to the end of starting yet another unremarkable academic career.

    Of course, the illusion of "perfect" software never fails to amuse me, since I remember an Interdata 32 overheating in the lab and making serious fixed point arithmetic errors. Sort of grounds one in reality, doesn't it, when the machine can't add. Sure glad the program was declared "correct," though.

  • Congrats to Ed. (Score:1, Interesting)

    by Anonymous Coward on Monday February 04, 2008 @08:45PM (#22300844)
    I was a PhD student of Ed, so great news for being at a "Turing award distance" 1. The model checking technique has indeed come a long way since its inception in 1981. It is more successful in hardware verification, then in software verification, so much so that most chip makers use it in one form or another. To those who say that the specification becomes as complex as the original program itself, there is some truth to that. However, one can also start with simple specifications, like After a request is made to a bus arbiter, it is always granted (within a few cycles, or eventually), or that there is no deadlock, etc. These are simple specifications, that can be "model checked". Moreover, people have developed sugar coating around mathematical languages used for writing the specs, and for analyzing specs themselves, etc. etc. There are techniques such as "equivalence checking", which can be thought of as a special case of model checking, where two designs need to proven equivalent to each other (say one version of RTL v/s a low power version of the same RTL). In this case, the specs become really simple (like which inputs and outputs corresponds between the two designs, and the relative timings).

    PS: Too lazy to create a slashdot account, so posting as an AC, besides, what's there in a name. :)
  • by El Cabri ( 13930 ) on Monday February 04, 2008 @08:50PM (#22300906) Journal
    The formal specification for, say, liveness of an interlocking system is a one-liner in a typical temporal logic notation, and you can apply it without significant modification to any number of different implementations, of any number of different applications, whatever their complexity. This is leverage : you put your trust in a very short piece of "code" (the formal spec for your property) and in the tool itself (which is the same kind of trust you put in your compiler), and in return you get trust on a huge complicated piece of software that you wrote. Then you break down your testing into many, independent property checks that all validate one aspect of one big piece of inter-mangled software. That's hugely powerful.

    I hope your prof failed you.
  • by omnirealm ( 244599 ) on Monday February 04, 2008 @09:12PM (#22301156) Homepage
    I signed up for Emerson's graduate course on model checking and reactive systems a couple of years back. The first day of class, he walked in 15 minutes late and said something like, "Welcome to my class. No homework or tests. Everyone gets an 'A'. Let's see what kind of papers we can come up with." He then dived right into some intense theory as if he were casually picking up a conversation he left off the semester before. I spent the next few hours feeling like total deadweight (several other grad students just sat there silent the whole time, with expressions on their faces like deer caught in headlights). I wound up just dropping the class; it took me another year of grad courses to get all the background theory I needed to just keep pace, and I hate wasting time, even for an easy 'A'. Too bad I graduated just before he taught his class again; I would have given it another shot before leaving UT Austin.
  • by rayadoCanyon ( 1233260 ) on Monday February 04, 2008 @09:13PM (#22301166)

    Once I went to a talk about applications of model checking to the verification of software. A programmer was constantly changing a state-based algorithm for call setup in a telephone switch, and was having trouble keeping it correct. Enter model checking. Two people wrote temporal specifications of call setup, and every night or so, they'd grind the model checker on the latest version of the code. No, that didn't prove the code was correct, but it did catch an enormous number of bugs in a tricky piece of concurrent code.

    Oh. The programmer was Ken Thompson. The people applying the model checker were Gerard Holzmann (the designer of SPIN) and Margaret Smith.

    I'm not saying the technology is applicable everywhere, but you gotta give Clarke, Emerson, and Sifakis a lot of credit for opening a good door.

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