z@rocksvax.UUCP (Jim Ziobro) (09/11/84)
This came across an internal mail list:
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Date: 5 Sep 84 15:01:17 PDT (Wednesday)
From: Don Woods <Woods.pa>
Subject: chess problem
To: Chess^, AllGames^, Puzzles^.es
Reply-To: Woods.PA@Xerox
A friend of mine is working on a program to analyse chess endgames, and
tested it out on the endgame consisting of a white King and two Bishops
versus a lone black King. This is commonly known to be a win for White.
To his surprise, he found that this is not quite true, and he presented
me with the following interesting problem:
Modulo symmetries of the chessboard (i.e., ignoring rotations and
reflections), there are 65 positions with king and 2 bishops vs. lone
king in which the two bishops, on move, cannot force mate.
Find them.
-- Don.
p.s.: The two bishops are, of course, traveling on different colors.
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Replies should go to Woods.Pa@Xerox.ARPA if you feel so inclined.
--
//Z\\
James M. Ziobro
Ziobro.Henr@Xerox.ARPA
{rochester,amd,sunybcs,allegra}!rocksvax!zhumbert@ihuxj.UUCP (humbert) (09/12/84)
Problem: King and 2 Bishops vs. King; superior side cannot force mate. Place the lone King on QR8. Place the other King on QB7, one bishop on QR7, and the opposite-colored bishop anywhere you like (except on the QR8-KR1 diagonal, of course). The superior side, to move, cannot force mate. If the bishop on QR7 moves, the lone King is stalemated. If the King moves from QB7 to QN6, the lone King is stalemated. Any other move allows K x B as a reply, reducing the superior force to King and 1 Bishop vs. King, which is insufficient force to establish a checkmate position. The practicality of the problem is reduced somewhat by the fact that the above position could never occur in a real game. Please correct me if this posting contains an error. jfs