Monday, August 24, 2015

50-Cent Puzzles....

It's always a good weekend when I find a Raymond Smullyan book on sale for 50¢ in a local thrift store. This was a good weekend.
So we'll ease into the week with three simple quickies from the master logician (the first two I've adapted from the book, and the last one is verbatim from Smullyan):

1)  \$5000 is stolen from a local store.  The robber or robbers make their get-away in a car. Soon thereafter 3 well-known criminals, A, B, and C, are picked up by law enforcement for questioning, and 3 facts are established:

a)  NO ONE other than A, B, and/or C was possibly involved in the crime.
b)  C NEVER pulls a robbery without A (and possibly others) also being involved.
c)   B does NOT know how to drive.

Is A innocent or guilty?

2)  A train leaves from Boston heading to New York at 2 pm., and one hour later another train leaves New York heading for Boston on a parallel track, moving the same speed as the first train. Which of the two trains will be closer to Boston when the two meet?

3)  And lastly, this riddle from Smullyan:

"Those of you who know anything about Catholicism, do you happen to know if the Catholic Church allows a man to marry his widow's sister?"

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1)  yes A is guilty (B couldn't do it by himself, because he couldn't drive the get away car, and if he did it with C, than, by #2 A must also be a guilty party. C couldn't have acted on his own without A.
A could've acted on his own, or with B or C, or both, but in some form had to partake.

2)  of course at the time they meet the two trains will be the same distance from Boston (...though a technical sort might argue that if by "meeting" one means the front of the locomotives meeting, than the tail/caboose end of the Boston train would still be "closer" to Boston).

3)  a dead man (widow's spouse) can't marry anyone!