Monthly Archives: May 2011

Generalizing Fitch Cheney’s Five-Card Trick

Ok, this should be the last of the card magic for a while.  But there is actually some relevance to recent discussion, as we will see; I was reminded of this trick by the prisoner puzzle from the last couple … Continue reading

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Prisoner Puzzles

Before discussing the solution to last week’s problem, I want to mention another interesting problem, which led to this latest one: 100 Prisoners. This is perhaps my favorite of the many of the “prisoners-with-a-strategy-for-collective-survival” type.  It goes as follows: you … Continue reading

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A Prisoner Puzzle

This week I want to share what I thought was a very clever puzzle.  I stumbled upon this via the usual roundabout path, while investigating some new results I had learned about a couple of other problems.  This puzzle turns … Continue reading

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CAPTCHAs revisited

This past week I spent some time experimenting with hacking the CAPTCHAs at the login page for one of my online financial institutions.  (See here for a discussion almost a year ago about reCAPTCHAs, a particularly interesting additional application of CAPTCHAs.) … Continue reading

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