jeff@heurikon.UUCP (02/25/84)
Here is the solution for Part 1 of the chess puzzle. I'm also posting (separately) a hint for Part 2, as a reward for those of you who have already made it this far. Black (lower case) .-----------------. | - * - * k * - * | Part 1: White to play and mate in two. | * p * - P - * p | | - * N * P * N * | Part 2: At first blush there appear to be | * - P p K p P - | two possible solutions. Prove that | - * - P p P - * | there can be only one. | * - * - P - * - | | - * - * P * - * | Solution: Part 1: see below. | * - * - * - * - | Part 2: will be coming soon. `-----------------' White (Caps) Caution: Don't confuse the "P"s and the "p"s. White is moveing UP, Black is comming DOWN. Solution "A": 1) P(N5)xP (en passant) ... 2) P-B7 mate Solution "B": 1) P(B5)xP (en passant) ... 2) P-Q7 mate Reasoning: Black's last move had to be either P-B4 or P-Q4. There are no other previous legal positions for Black to have been in. The black King could not have just moved into its present position, else Black would have been in check for more than one move (The whilte pawns in the area couldn't have just got there). Similarly, the other black pawns are trapped and could not have just moved. Neither of the two black pawns could have just come from Black's 3rd rank. If Black had had a pawn on B3 or Q3, White would have been in check when Black played P-[BQ]4, which makes no sense. (Such a position would have been illegal.) Thus, the pawn started from B2 (or Q2), giving White the option of capturing en passant. Only *one* of the above solutions is correct. Part 2 asks: which one? -- /"""\ Jeffrey Mattox, Heurikon Corp, Madison, WI |O.O| {harpo, hao, philabs}!seismo!uwvax!heurikon!jeff (news & mail) \_=_/ ihnp4!heurikon!jeff (mail - fast)