[net.puzzle] *SPOILER* Re: A puzzle with two answers?!?

keesan@bbncca.ARPA (Morris Keesan) (11/13/84)

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The key to the problem, and the source of the hidden assumption, is that no
cannibal can ever claim to be tall.  Short cannibals (truth-tellers) will
always say they are short, and tall cannibals (liars) will also say they are
short, IF THEY ARE MAKING STATEMENTS ABOUT THEIR HEIGHT.

The two possible scenarios are:

1) Short, Short, Tall.  First cannibal said, "I am short," but was drowned out
    by the sound of the waves.

2) Tall, Tall, Short.  First cannibal said, "My mother wears army shoes," or
    some other false statement irrelevant to the problem.  Second cannibal
    (tall liar) said, "He said he is short.  He is short.  I am short."  All
    three statements are lies.  Third cannibal (short truth-teller) exposes
    these lies, and correctly claims to be short.

The fallacy in the obviously intended first answer is in assuming that the
first cannibal said something about his height.
-- 
			    Morris M. Keesan
			    {decvax,linus,ihnp4,wivax,wjh12,ima}!bbncca!keesan
			    keesan @ BBN-UNIX.ARPA

ndiamond@watdaisy.UUCP (Norman Diamond) (11/14/84)

There are more difficulties than have been mentioned so far.  They are
exemplified by the "spoiler" which this message is replying to.
The liars always say the opposite of what they believe.  If a liar says
"A and B and C", does that mean that the liar believes "(not A) and
(not B) and (not C)", or only that he believes "not (A and B and C)"?
In the original problem, the second speaker only stated one sentence,
in conjunctive form.  There are bucketfulls of interpretations.
The followup message reduced the possibilities to two by changing the
second speaker's message into three separate statements, thereby
inferring that all three statements are false (or that all three are
true).  If my life depended on solving the original problem, I would
ask for a coin to flip.

hollis@ucf-cs.UUCP (William ) (11/17/84)

The tall cannibals ALWAYS lie, ie, they can tell no truth, and the short
cannibals ALWAYS tell the truth.

William Kendall Hollis

 ...decvax!ucf-cs!hollis or ...duke!ucf-cs!hollis
        hollis.ucf-cs@Csnet-Relay