Chess puzzle.

[George Tsavdaris]

Can you reconstruct the game that leads to the following position, in 13 moves or less?
Can you also do it with 2 different ways?
[d]2k4r/1bpp1ppp/1p1r1p2/2b5/4n3/q7/P1PPPPPP/RNBQKBNR b KQ - 0 1
It's black to move as it is shown from the EPD of course.

[Cubeman]

I have found 1 solution, it took me a while so I can't be bothered with a shorter or alternative.I suppose the Knight move order at the end can be changed e.g instead of Na6 you could have Nc6.Anyway here is a sample game.
1.Nc3 Nf6
2.Nd5 Ne4
3.Nf6+ exf6
4.b4 Qe7
5.b5 Qa3
6.b6 Bc5
7.bxa7 b6
8.axb8=N Bb7
9.Na6 0-0-0
10.Nb4 Rde8
11.Nd5 Re6
12.Nc3 Rd6
13.Nb1
Have you got a faster way?

[Ovyron]

Impressive. How hard would it be to make a program that "backsolves" such positions?

[Cubeman]

I just realised that I can't change the Knight moves from Na6 to Nc6 since black would not be able to castle.I will look for alternative!

[Cubeman]

Just found a new solution that Rybka will never find
1.b4 Nf6
2.Bb2 Ne4
3.Bf6 exf6
4.b5 Qe7
5.b6 Qa3
6.bxa7 Bb4
7.axb8=B! Ra6
8.Ba7 Rd6
9.Bd4 b6
10.Bb2 Bb7
11.Bc1 Kd8
12.Bb2 Kc8
13.Bc1
And this time instead of 12.Bb2 and 13.Bc1 you can insert 12.Nc3 and 13.Nb1.

[Cubeman]

Dam just saw the last solution does not work, the Black Bishop is on b4 not c5.New solution.
1.b4 Nf6
2.Bb2 Ne4
3.Bf6 exf6
4.b5 Qe7
5.b6 Qa3
6.bxa7 Bc5
7.axb8=B! Ra6
8.Ba7 Rd6
9.Bb6 Kd8
10.Ba5 b6
11.Bc3 Bb7
12.Bb2 Kc8
13.Bc1

[Mike S.]

Such a program exists: Natch, and it's interface iNatch, for Linux, Mac or Windows.

http://natch.free.fr/Natch.html

I did not try it now because the download is slow, but I remember that I did try it some years ago, on another computer. It can backsolve such positions and find so called "shortest proof games". IIRC, it works quite fast.

(I read on the Natch page that Vista users shouldn't use more that 27 MB hash if Natch crashes.)

[AdminX]

Such a program exists: Natch, and it's interface iNatch, for Linux, Mac or Windows.

http://natch.free.fr/Natch.html

I did not try it now because the download is slow, but I remember that I did try it some years ago, on another computer. It can backsolve such positions and find so called "shortest proof games". IIRC, it works quite fast.

(I read on the Natch page that Vista users shouldn't use more that 27 MB hash if Natch crashes.)

Never let it be said that you are not on top of your game Mike!

PS: This is not for Vista users. , but for Dos - WinXP and Linux

[Cubeman]

Will Natch find alternative solutions too?