Derek Kisman’s Ex Post Facto

I already wrote about two puzzles that Derek Kisman made for the 2013 MIT Mystery Hunt. The first puzzle is now called the Fractal Word Search. It is available on the Hunt website under its name In the Details. I posted one essay about the puzzle and another one describing its solution. The second puzzle, 50/50, is considered one of the most difficult hunt puzzles ever. Unfortunately, the puzzle is not available, but my description of it is.

Today let’s look at the third puzzle Derek made for the 2013 Hunt, building on an idea from Tom Yue. This is a non-mathematical crossword puzzle. Derek tends to write multi-layered puzzles: You think you’ve got the answer, but the answer you’ve got is actually a hint for the next step.

Often multi-layered puzzles get solvers frustrated, but the previous paragraph is a hint in itself. If you expect the difficulty, you might appreciate the fantastic beauty of this puzzle.

Welcome to Ex Post Facto.



  1. James:

    You have linked to the solution of Ex Post Facto, not the statement!

  2. tanyakh:

    Thank you James, I fixed the link.

  3. not important:

    Thanks for sharing – I was in the same year at Waterloo with Derek. What an amazing feeling to virtually “run” into someone I last saw almost 20 years ago. Derek was a very smart guy in college (of course he is still a very smart guy :)).

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