From: Ivan Godard <ig@solaris.kala.com>
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Subject: For BoE Articles

The trouble with word puzzles, especially those 
many riddles which depend on a pun for their
meaning, is that they don't work well for
players with differing native language or culture.
Similarly algebra puzzles are trivial
for those who know it, and impossible for 
players too young or liberal arted to have done
algebra.

Puzzles need to be expressible clearly and
succinctly even across languages, and to require
no particular knowledge other than the universals
of the human condition. Good puzzles which pass
this test are few in my experience. Here's one
of my favorites:

You and your spouse (assume you have one) enter
a room in which there are already four other
couples. There follows a round of introductions
and hand-shaking. From happenstance or prior
acquaintance, not everyone shakes everyone else's
hand. In particular of course, no one shakes
their own hand or the hand of their own spouse.

After the introductions are complete, out of
curiosity you ask each of the nine other people
in the room how many different people they had
shaken hands with. You get nine different
answers.

How many people did your spouse shake hands with?

Ivan

p.s. Yes, I know that it looks underconstrained,
but it's not.