A retrograde analysis problem

What was the first move of the black queen?

c8?

Originally posted by alexdino
c8?

Prove it

Originally posted by David113
Prove it

considering the pawns its the only logical way(except if you move the king first)................
aaaggghhhh.................. i can't prove it!

Originally posted by alexdino
considering the pawns its the only logical way(except if you move the king first)................
aaaggghhhh.................. i can't prove it!

Use your favorite chess program to compose a game ending in this position...

couldn't you just tell me if this is the solution because i can't find a program on the net that creates chess games
i'd really want to see an explination , could you posibly send it to me?
Thanks

Originally posted by David113
[fen]1b4b1/2pppp1P/1p3p2/6p1/8/P3P3/RPPP1p2/r1nKrk2[/fen]

What was the first move of the black queen?

8 White pieces on board + 7 necessary bP captures + 1 Bc1 dead @ home = 16.
14 Black pieces on board + 0 necessary P caps = 14.

The only possible place wBf1 could have died is g6 - the only light square on which a bP could have captured.

To get bNc1 out of there, I need a wNb1 to shield. No other piece can get in [bNc3 is illegal check to wK].

Retraction starts -1...Re2 -2.h6 Rb1 freeing wR. Now, how do I get my wN back on the board? Pf2 is stuck until Pe3 steps back. Pg5 is reserved for uncapturing on g6. It must be g7xNf6. But I can't retract that until Bf8 is home, and he can't retract home until Pb7 is back, which can't step back until Bc8 is home. And all of that can't be retracted with bK outside the pawn chain. Bc8, Bf8, and Ke8 must all go home before a wN can appear.

The resulting intermediate position is:


From here, it could go -1.Nd5 Kd8 -2.Nc3 Ke8 -3.Ra2 Ra1 -4.Nb1 Nd3 -5.Kc1 Nc6 -6.Kd1 Na4 -7.Kc1 Nc3 -8.h4 Nd1 -9.h3 Re1 -10.e2 fe3[+P] -11.h2 ed4[Q or R both work fine].

The new piece on d4 unpromotes on h8 and uncaptures on g5 to fix the pawn structure. The rest of the pieces can easily leave the first rank. The position is unwound.

It's important to note that White must save his h-pawn tempos, thus making it impossible to even think about uncapturing a Q earlier [later?!] on.

bQ never moved.

Originally posted by alexdino
couldn't you just tell me if this is the solution because i can't find a program on the net that creates chess games
i'd really want to see an explination , could you posibly send it to me?
Thanks

See the solution by SwissGambit.

Originally posted by SwissGambit
8 White pieces on board + 7 necessary bP captures + 1 Bc1 dead @ home = 16.
14 Black pieces on board + 0 necessary P caps = 14.

The only possible place wBf1 could have died is g6 - the only light square on which a bP could have captured.

To get bNc1 out of there, I need a wNb1 to shield. No other piece can get in [bNc3 is illegal check to wK].

ossible to even think about uncapturing a Q earlier [later?!] on.

[b]bQ never moved.[/b]

Correct solution 🙂

Here is a PG:

1.g4 Na6 2.a3 Nb8 3.Ra2 Na6 4.Nc3 Nb8 5.Bg2 Na6 6.Be4 Nb8 7.Bg6 Na6 8.Nh3 Nc5 9.Kf1 hxg6 10.Kg2 Rh4 11.g5 Nh6 12.gxh6 Nb3 13.Kf3 Nxc1 14.Rg1 Nb3 15.Rg5 Na5 16.Qh1 Rg4 17.Rc5 Rg1 18.Ng5 Ra1 19.Nb1 Nb3 20.Kg2 Na5 21.Kf1 Nb3 22.Ke1 Na5 23.Qc6 Nc4 24.Kd1 Ne3+ 25.Kc1 Nd1 26.Qb6 axb6 27.Ne6 Ra4 28.Nxd8 Rg4 29.Ne6 Rg1 30.Nd4 Kd8 31.h7 Re1 32.h8Q bxc5 33.Qh3 cxd4 34.Qe3 dxe3 35.h3 exf2 36.e3 Re2 37.h4 Nc3 38.h5 Nb5 39.Kd1 Nd4 40.Kc1 Nb3+ 41.Kd1 Nc1 42.Nc3 Ke8 43.Ne4 Rb1 44.Nf6+ gxf6 45.Ra1 Bh6 46.Ra2 Bf4 47.Ra1 Kf8 48.Ra2 Kg7 49.Ra1 Kh6 50.Ra2 Kg5 51.Ra1 Kg4 52.Ra2 Kg3 53.Ra1 Kg2 54.Ra2 Kf1 55.h6 g5 56.Ra1 Be5 57.Ra2 Bd4 58.Ra1 Ba7 59.Ra2 Bb8 60.Ra1 b6 61.Ra2 Bb7 62.Ra1 Be4 63.Ra2 Bh7 64.Ra1 Bg8 65.Ra2 Ra1 66.h7 Re1#

(Composer is Luigi Ceriani, the father of modern retro-problems)

Originally posted by David113
Correct solution 🙂

Here is a PG:

1.g4 Na6 2.a3 Nb8 3.Ra2 Na6 4.Nc3 Nb8 5.Bg2 Na6 6.Be4 Nb8 7.Bg6 Na6 8.Nh3 Nc5 9.Kf1 hxg6 10.Kg2 Rh4 11.g5 Nh6 12.gxh6 Nb3 13.Kf3 Nxc1 14.Rg1 Nb3 15.Rg5 Na5 16.Qh1 Rg4 17.Rc5 Rg1 18.Ng5 Ra1 19.Nb1 Nb3 20.Kg2 Na5 21.Kf1 Nb3 22.Ke1 Na5 23.Qc6 Nc4 24.Kd1 Ne3+ 25.Kc1 Nd1 26.Qb6 axb6 27.Ne6 Ra4 28.Nxd8 Rg4 29.Ne6 Rg1 30.Nd4 ...[text shortened]... a1 Bg8 65.Ra2 Ra1 66.h7 Re1#

(Composer is Luigi Ceriani, the father of modern retro-problems)

Do people really solve these by playing forward from move one, or do they play forward from move one after they've already solved it? 😉

Originally posted by SwissGambit
Do people really solve these by playing forward from move one, or do they play forward from move one after they've already solved it? 😉

They play random moves, until they get the desired position by chance.

Originally posted by David113
They play random moves, until they get the desired position by chance.

That may explain why very few people stay interested in solving this type of problem. A systematic approach, working backwards, is the way to go.

Originally posted by SwissGambit
It's important to note that White must save his h-pawn tempos, thus making it impossible to even think about uncapturing a Q earlier [later?!] on.

I missed the point with this comment. Why not retract Ra1xQa2 in the early retraction? The answer is that she would need to go home to d8 before Nf6 appears, thus depriving bK of the d8 square!