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From: lew@ihuxr.UUCP
Newsgroups: net.math
Subject: A few last words on the quiz paradox
Message-ID: <637@ihuxr.UUCP>
Date: Thu, 15-Sep-83 18:53:52 EDT
Article-I.D.: ihuxr.637
Posted: Thu Sep 15 18:53:52 1983
Date-Received: Fri, 16-Sep-83 23:01:24 EDT
Organization: BTL Naperville, Il.
Lines: 24

I can except the explanation of the surprize quiz/unexpected hanging
"pseudo-paradox" that Jerry Leichter gave. I assume this is the canonical
explanation. I would only note that it hinges on the meaning of "know",
as Jerry indeed explicitly stated. When I reformulated the problem I was
attempting to avoid the involvement of the prisoner/students mental state
by substituting "infer" for "know". Note that when Monty Ellis challenged
anyone to come up with a way to DETERMINE that the quiz would be on (say)
the 15th, he changed the language that he had just reworded himself. That
the INFERENCE can be formed is the basis of the original paradox.

If you finally nail the formulation down so that it is undeniably self-
contradictory, all you are left with is that every finite sequence must
have a last element. The paradoxical statement is, "The quiz cannot
possibly occur on the last day that it can possibly occur." I hope
no one will argue that this is not a self-contradiction.

A more prosaic, but really quite clever resolution of the paradox (in its
quiz form) was suggested by C. J. Holzwarth. The teacher can give
a "pseudo-quiz" every day, with one of them being the real quiz. This
obviously wouldn't work for the hanging! This is just like a fable where
an elf promises not to remove a marker from a tree where a treasure
is hidden, but he places identical markers on every tree in the forest.
 
		Lew Mammel, Jr. ihuxr!lew