Review

From: Ankur Jain (ankur@cs.washington.edu)
Date: Wed Dec 01 2004 - 12:35:17 PST

  • Next message: Katarzyna Wilamowska: "The evolutionary origin of complex features"

    This paper tries to empirically study if evolutionary theory can indeed
    be used to explain the development of complex features such as eyes in
    organisms; and hence put to rest some of the concerns that have been
    raised about the theory in the past. For this, the authors trace the
    evolution of a complex reward function in "digital organisms" which
    started off without having any rewarding function. They make a couple of
    interesting observations --

    1) complex functions gradually evolved from several simpler functions
    which served as their foundation.

    2) even if simpler functions eventually got replaced by more complex
    functions, it was essential that the simpler functions got rewarded when
    they had appeared. If not, the complex functions did not get developed
    at all.

     From an AI perspective, their approach, in essence, boils down to a
    local search of a very very large space with many good states. The
    appearance of simple functions gives an indication of whether the search
    is along the right path or not. Mutations provide for a mechanism to
    make the search proceed. And just like local search, there might be some
    moves that might in the short-run prove bad, but in the long run help
    moving towards the final goal states.

    While a very nice self-containing paper in itself, I was at loss
    understanding how there experiments are very different from the genetic
    algorithms that have for long been proposed in the AI literature. The
    one significant point of departure could be that they show that
    development of *complex features* is indeed possible within this model.
    But isn't developing a complex feature akin to finding one of the goal
    states which have that feature?

    As an aside, and the authors mention this too, it would have been
    interesting having a similar study on sexual reproduction. Also,
    probably something closer to reality would be to have more than just a
    discrete set of reward functions.


  • Next message: Katarzyna Wilamowska: "The evolutionary origin of complex features"

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