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Gerald Jay Sussman on Flexible Systems

  • Jan 7, 2016 · 7:00 PM
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Flexible Systems
The Power of Generic Operations


Most systems we build work well for the application that they were designed for, but they are brittle in that adapting to even small changes in the problem requires large changes in the code.  Can we optimize for flexibility, trading off other virtues like proofs of correctness or efficient execution?  I think this is often the right path.

Indeed, Postel's Law, "Be conservative in what you do, be liberal in what you accept from others," is strong advice for enhancing robustness in open systems.

In the spring term I teach an advanced programming class, where the goal is to learn how to avoid programming oneself into a corner.  One of the most powerful (and dangerous) techniques for enhancing flexibility is the use of extensible generic operations.

I will show where it is to our advantage to make systems with extensible generic operations, and how to control such systems.


Gerald Jay Sussman is the Panasonic Professor of Electrical Engineering at the Massachusetts Institute of Technology (MIT). He received his S.B. and Ph.D. degrees in mathematics from MIT in 1968 and 1973 respectively. He has been involved in artificial intelligence research at MIT since 1964. His research has centered on understanding the problem-solving strategies used by scientists and engineers, with the goals of automating parts of the process and formalizing it to provide more effective methods of science and engineering education. Sussman has also worked in computer languages, in computer architecture and in VLSI design.

Sussman is a coauthor (with Hal Abelson and Julie Sussman) of the introductory computer science textbook Structure and Interpretation of Computer Programs. It was used at MIT for several decades, and has been translated into several languages.

Sussman's contributions to artificial intelligence include problem solving by debugging almost-right plans, propagation of constraints applied to electrical circuit analysis and synthesis, dependency-based explanation and dependency-based backtracking, and various language structures for expressing problem-solving strategies. Sussman and his former student, Guy L. Steele Jr., invented the Scheme programming language in 1975.

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  • Jeff P.

    4 · January 12, 2016

  • Ilir K.

    Good but difficulties with the acustics...

    1 · January 8, 2016

  • mark p.

    2 · January 8, 2016

  • Pierre de L.

    Gerry gave an intelligent and inspiring presentation.

    5 · January 8, 2016

  • Ben

    Sussman is a genius.
    Here's an essay of his that has many of the same ideas he discussed tonight. The theme of this essay is that extensible generics allows for robust systems.

    4 · January 7, 2016

  • Ashley C.

    Great topic. Great speaker. Fun Q&A.

    2 · January 7, 2016

  • Bennett T.

    Very cool ideas, enthusiastically presented, time flew.

    1 · January 7, 2016

  • David

    Are you still coming to McKnight pub afterwards?

    January 7, 2016

  • Tendekai M.

    So I got there at 7.15 and was turned away at the door. They said it was full to capacity. :( If you guys are hanging out somewhere after, let me know

    January 7, 2016

  • Ashish A.

    I had a last minute emergency and cannot attend. Sorry, I hope someone on the wait list can take my spot.

    January 7, 2016

  • Tom S.

    I (unfortunately) may not be able to attend tonight. I'll update my RSVP if I can't. But do you plan to share a recording of the presentation?

    January 7, 2016

  • Bennett T.

    Is the street address 111 or 625? The calendar entries seem to disagree

    January 7, 2016

    • Harry M.

      Its 625 pivotal

      1 · January 7, 2016

    • Bennett T.

      Google seems to think that Pivotal Labs' NYC office is at 625, hope that's the right one.

      January 7, 2016

  • Perry M.

    I can't make it after all so I just changed my RSVP to "no" so someone on the wait list can go instead.

    January 7, 2016

  • Raymond P.

    Unfortunately, I'm still sick so can't make it to the talk. Hopefully, I'll feel better a month from now and so be able to catch up with you all then.

    January 7, 2016

  • Eugene J.

    Too late to see the event. If there is a slot, i will be glad to attend.

    January 7, 2016

  • Sam

    Hi, just saw this event. It seems there're still 6 spots but the reservation is closed. Is there any chance to join? If not, will this event be recorded on youtube?
    Many Thanks

    1 · January 6, 2016

  • Manish K.

    Would love to attend but I'm on the waitlist. Any chance the talk will be recorded?

    3 · January 6, 2016

  • Juan S.

    So sad I will miss this. I wanted to get my copy of SICP signed.

    2 · December 28, 2015

    • Pierre de L.

      Pete: I can't say for sure but I trust that Gerry will be happy to sign copies of his book after the presentation. I will check with him. I actually have an autographed copy of his PhD thesis "A Computer Model of Skill Acquisition" and would now also like too get my SICP copy signed as well. :-)

      1 · December 31, 2015

    • Juan S.

      @Geoffrey: Thanks! I am not sure how since I and my copy of SICP are in Texas until the 18th :-) But PM me/let me know.

      January 4, 2016

  • Kyle L.

    I was curious whether Meetup would still let me attempt to update my reservation with a +1, and now it appears I've been bumped to the waitlist. I guess that's my punishment for doing my tests in production.

    1 · January 4, 2016

  • Pierre de L.

    After Gerry Sussman's talk we'll be heading over to McKenna's Pub for some drinks and networking.

    The Address is:

    McKenna's Pub
    250 W 14th St,
    New York, NY 10011

    This is between 7th & 8th Ave, 4 blocks South of Pivotal Labs and 1 block West.

    2 · January 4, 2016

  • Pierre de L.

    Gerry Sussman will be happy to sign copies of SICP after his presentation. :-)

    3 · December 31, 2015

  • Geoffrey K.

    Also bringing my son Alexander Knauth.

    2 · December 28, 2015

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