[net.puzzle] The solution to the S and P puzzle

ags@pucc-k (Seaman) (11/23/83)

Sorry, but you blew it.  You said that 23 was one of the possible sums that
S might have, such that P could not determine the sum.  As you already
pointed out, one of the possible products corresponding to 23 is 76.

If I am P, and I see that the product is 76, and if I also know that the
sum is less than 40, then I can immediately conclude that the sum is 23.
How?  Because the only admissible factorization of 76 is 4 * 19, and
4 + 19 = 23.   Note that 2 * 38 = 76 is NOT an admissible factorization
in your version of the puzzle, since the sum is not less than 40.

Therefore, when S announces that P does not know the sum, you can conclude
(since S does not make mistakes) that his sum is NOT 23.  The rest of the
analysis is exactly as I posted earlier, and every word of it is correct.
The only possible sums are 11 and 17, and there is no way for S to
determine the product.

				Dave Seaman
				..!pur-ee!pucc-k!ags

ags%pucc-k@phs.UUCP (Seaman) (11/23/83)

References: <576@alberta.UUCP>
Relay-Version:version B 2.10.1 6/24/83; site duke.UUCP
Posting-Version:version B 2.10.1 6/24/83; site pucc-k
Path:duke!decvax!genrad!grkermit!masscomp!clyde!ihnp4!inuxc!pur-ee!CS-Mordred!Pucc-H:Pucc-I:Pucc-K:ags
Message-ID:<119@pucc-k>
Date:Wed, 23-Nov-83 09:58:39 EST
Organization:Purdue University Computing Center

Sorry, but you blew it.  You said that 23 was one of the possible sums that
S might have, such that P could not determine the sum.  As you already
pointed out, one of the possible products corresponding to 23 is 76.

If I am P, and I see that the product is 76, and if I also know that the
sum is less than 40, then I can immediately conclude that the sum is 23.
How?  Because the only admissible factorization of 76 is 4 * 19, and
4 + 19 = 23.   Note that 2 * 38 = 76 is NOT an admissible factorization
in your version of the puzzle, since the sum is not less than 40.

Therefore, when S announces that P does not know the sum, you can conclude
(since S does not make mistakes) that his sum is NOT 23.  The rest of the
analysis is exactly as I posted earlier, and every word of it is correct.
The only possible sums are 11 and 17, and there is no way for S to
determine the product.

				Dave Seaman
				..!pur-ee!pucc-k!ags