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charlie, computer cat

January 2018



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:p kittie

Alex introduced me to the blue eyes puzzle - The Hardest Logic Puzzle in the World, according to xkcd. At 11pm after we'd just finished the Prestige (we showed my parents - they agreed it was great!). Cue 30-40 minutes or so of intense thinking and talking it over but we figured it out. Then we went to bed and I ended up turning it over and over in my head - the solution is really hard to get your head around. It was way worse than caffine for getting my head all fizzing but it was good to know I still have my chops as a logician :) (solution here if you want)

The rest of the weekend was much more relaxing - visit from my folks, which is always good, and the tennis at Queens. I suddenly realised that actually Wimbledon doesn't clash with Glastonbury at all this year because it's not for another week and was far too pleased with this realisation - 2 weeks of tennis to come! That should help me recover from the mud I fear we are doomed to :)

I've got the Brownies stuff all sorted out, I think but I'm way behind with my history study for this unit :( I really need to get my butt in gear as I have an essay due a week after I get back and no clue what to write for it so far. I'll have to try to get some of that done tonight - I don't think that a muddy field is the best place for my course books!
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Well, I'd heard this one a while ago, or something similar, so it took about half an hour to 45 mins of puzzling thru while doing computery stuff. But - shouldn't you also link to the answer? or did he purposefully not put it on line?

('Cue' not 'Queue' in this case, by the way - it's referring to acting not waiting.)

Raymond Smullyan's "What is the name of this book?" is very good for that sort of puzzle. In fact it may be the place I first saw this one.
I forgot he hadn't linked it from the puzzle, actually. Perhaps I should go back and add it.

'Cue' not 'Queue' in this case, by the way - it's referring to acting not waiting.)

Took me a few minutes.

But i've heard it before, and i spent that time remembering rather than ratiocinating, so this is not so impressive. Or rather, i knew the general shape of the answer and the reasoning, and i just had to work out the details again.

It's an interesting puzzle, because you can pretty much work out the answer from symmetry arguments without knowing the mechanism; i don't know if this makes it easier or not!

-- tom

It's a good puzzle but it can't possibly compete in difficulty

...with some of the stuff towards the back of Raymond Smullyan's book previously mentioned. Some of the stuff in his book also relies on the characters being perfect logicians, absolute truth-tellers, and infallible observers - but he also mixes in knaves who always tell lies, normals who sometimes lie and sometimes tell the truth, mad knaves who think they are lying but actually tell the truth (and mad knights who lie equally inadvertently), and Tweedledee and Tweedledum who tell lies and truth on alternate days of the week (and both tell the truth on Sunday - the question is how to find out what weekday it actually is).