15 Nov 05
1 edit
Originally posted by BigDoggProblemTrying to have a go at one of these proof games for the first time.
[fen]1n2k3/ppp1n2p/4p3/6pq/2r5/2b2p1b/PPPPPPPP/RNBQKBNR w KQ - 0 15[/fen]
Proof Game in 14.0 moves
(Position after Black's 14th move. How did the game go?)
R on c4 must have moved three times if from h8, B on c3 twice, other B once, Q twice, N on e7 once, eP once, f pawn 3/4 and g pawn 1/2.
As only 14 moves allowed those last pawns must have moved two squares initially. No captures possible.
Also therefore a white N must have captured the P at d7 and R at a8.
I've also noticed that the bN is four moves from the R, the gN three from the P.
So the order of blacks moves.
eP after wsB, but before Q, which is in turn before N.
bsB first move before R at all, but after gP. 2nd move last to allow N back.
But gP is after Q 2nd
I'm thinking that prior to N must capture the d7 P ASAP, i.e. on move three. fP can safely move twice before this, but I can't yet see a third move which black can then play before the N vacates its spot.
Random thoughts. Working on it, board out.....
Edit: And this post did take a while. Having caught a little of Mephisto's reply, I was able to figure out the rest of the moves quite quickly. Biggest problem seemed to be missing Qd5 (not Qg5).
17 Nov 05
Originally posted by BigDoggProblemBlack's moves were not too difficult to find (without the sequence). It was a lot harder to find the (purpose of the) 2 spare moves for white (Rh1-g3 via h4 - g4 to make room on the 3rd rank for the black rook and Qd1 -d5 - h5 - b5 to block the checking from the rook on h8. This is what I came up with:
Here's a tougher one:
[fen]rnbqkbnr/1pp1ppp1/1N4P1/1Q6/3R4/1PP3R1/1PP1PPPB/1N3BK1[/fen]
Proof Game in 24.5 moves
(position after white's 25th move)
1.h2-h4 a7-a5
2.h4-h5 Ra8-a6
3.Rh1-h4 Ra6-g6
4.h5xRg6 h7-h5
5.Rh4-g4 h5-h4
6.Ng1-f3 h4-h3
7.Nf3-e5 h3-h2
8.Ne5-c4 Rh8-h3
9.Nc4-b6 Rh3-c3
10.d2xRc3 h2-h1=R
11.Qd1-d5 Rh1-h8
12.Qd5-h5 d7-d5
13.Bc1-f4 d5-d4
14.Ke1-d2 d4-d3
15.Kd2-e3 d3-d2
16.Ke3-f3 Qd8-d5+
17.Kf3-g3 Qd5-b3
18.a2xQb3 d2-d1=Q
19.Ra1-a4 Qd1-d8
20.Ra4-d4 a5-a4
21.Kg3-h2 a4-a3
22.Kh2-g1 a3-a2
23.Bf4-h2 a2-a1=R
24.Rg4-g3 Ra1-a8
25.Qh5-b5
17 Nov 05
Originally posted by Mephisto2Yep, that's it. The theme is sacrifice of three original pieces (Q,R,R) followed by 'replacement' promoted pieces returning to their homesquares (dubbed the 'Pronkin' theme in honor of Dmitry Pronkin, the composer of this problem).
Black's moves were not too difficult to find (without the sequence). It was a lot harder to find the (purpose of the) 2 spare moves for white (Rh1-g3 via h4 - g4 to make room on the 3rd rank for the black rook and Qd1 -d5 - h5 - b5 to block the checking from the rook on h8. This is what I came up with:
1.h2-h4 a7-a5
2.h4-h5 Ra8-a6
3.Rh1-h4 Ra6-g6
4. ...[text shortened]... 0.Ra4-d4 a5-a4
21.Kg3-h2 a4-a3
22.Kh2-g1 a3-a2
23.Bf4-h2 a2-a1=R
24.Rg4-g3 Ra1-a8
25.Qh5-b5