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Thog Problem

Posted under Learning, Logic Problems by Kenny on Thursday 8 January 2009 at 5:04 am
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Given the following combinations of shapes and colors:

The experimenter makes the following statement:

“I am thinking of one color (black or white) and one shape (square or circle). Any figure that has either the color I am thinking of, or the shape I am thinking of, but not both, is a THOG. Given that the black square is a THOG what, if anything, can you say about whether the other figures are THOGS?”

Select the THOG by clicking on one of the shapes above


4 Comments »

  1. Comment by Greg Kennedy — June 27, 2009 @ 9:10 pm

    Let Whiteness = 0 and Blackness = 1
    Let Squareness = 0 and Circular = 1
    Then you can describe your THOG with two bits, one for color and one for shape
    XOR with 1 1 to find the opposite THOG.

  2. Comment by Kenny — June 27, 2009 @ 9:25 pm

    Nice. I never thought about it like that :)

  3. Comment by Joe Whitehead — July 21, 2009 @ 1:43 am

    Yeah, so the right shape must be either a white square or black circle. As above, the other THOG is a black square. If the right shape is a white square, then the black circle is neither a THOG or the right one. The opposite is also true.

    This problem just screamed “Boole” out to me!

  4. Comment by Joe Whitehead — July 21, 2009 @ 1:44 am

    Err black square and white circle*

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