Evan Martin (evan) wrote in evan_tech,
Evan Martin
evan
evan_tech

solving knowledge puzzles

Someone on a mailing list at work forwarded one of those logic puzzles that involve information being revealed by not knowing. Briefly: two numbers in [2,100] are chosen; A is told their product, B is told their sum; A says they don't know the numbers, B says they knew that fact and they also don't know the numbers; and with that knowledge A now knows the numbers.

It turns out that McCarthy wrote a paper: Formalization of two Puzzles Involving Knowledge on solving these puzzles in code.

And based on that, here's a Haskell solution to the problem that is quite nice -- ~20 lines of rather straightforward code. (On the other hand, I imagine that this is the sort of thing a logic programming language is more appropriate for.)
Tags: go read, haskell
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  • 11 comments

  • münchen

    On that note: I'm living in Munich for the next week plus a few days. Do I know anyone around here? (PS: The LJ → PubSubHubbub → Reader…

  • deb/rpm diffing tools

    Dear Linux hackers, Chrome tends to push minor updates (often security) pretty frequently. We'd like to operate as a good member of the Linux…

  • emacs

    I've been using vim for a very long time -- over ten years -- but over those years I've envied more and more the way emacs integrates other software.…