Come up with a position with the following properties:
Contest winner is the entrant whose move count is the smallest.
My entry into this contest is posted below. It takes 62 move-pairs.
Happy solving!
Bill Smythe
And here is my entry into this contest. It takes 62 move-pairs.
1.Nc3 d6 2.Na4 e5 3.Nb6 f5 4.Nxa8 f4 5.Nf3 g5 6.Nd4 g4 7.Nc6 g3 8.Nxb8 Bg4
White completes his knight development as black builds a ladder for white’s h-pawn.
9.e4 Kf7 10.Ba6 Ke8 11.Bxb7 Kf7 12.d3 Ke8 13.Be3 Kf7 14.Bxa7 Ke8
White develops his bishops as Rome fiddles.
15.hxg3 Kf7 16.gxf4 Ke8 17.fxe5 Kf7 18.exd6 Ke8 19.dxc7 Bf3 20.gxf3 Kf7
White’s pawn development is complete, as all his pawns are on the correct files.
21.Rxh7 Ke8 22.Rxh8 Kf7 23.Rxg8 Ke8 24.Rxf8 Ke7 25.Rxd8 Kf7 26.Rc8 Kg7 27.a4 Kh7 28.a5 Kg7 29.Ra4 Kh7 30.Rd4 Kg7 31.dRd8 Kh7
Rook development is now complete.
32.a6 Kg7 33.b4 Kh7 34.b5 Kg7 35.b6 Kh7 36.c4 Kg7 37.c5 Kh7 38.c6 Kg7 39.d4 Kh7 40.d5 Kg7 41.d6 Kh7 42.d7 Kg7 43.e5 Kh7 44.e6 Kg7 45.e7 Kh7 46.f4 Kg7 47.f5 Kh7
And now it will be the white king’s turn.
48.Ke2 Kh6 49.Ke3 Kh7 50.Ke4 Kh6 51.Ke5 Kh7 52.Ke6 Kh6 53.Kf7 Kh7 54.Kf8 Kh8 55.Qd5 Kh7 56.Qf7 Kh8 57.Qe8 Kh7 58.f6 Kh8 59.f7 Kh7 60.f4 Kh8 61.f5 Kh7 62.f6 Kh8
Game over.
Bill Smythe
Cute!
That is a very beautiful proof game! I find it hard to believe that someone hasn’t covered this territory before. If not, it’s a wonderful idea (a little mechanical, yes, but still…)
Is a faster solution possible, you ask? I wonder whether some of the rook’s Pac-Man behavior (moves 21-25) could be replaced by pawn captures. (Even after pawns are on “correct” files, they could leave those files & come back.)
One might discover something interesting by constructing a proof game for the reflection position (White Kc8, Black Ka8 or Ka7)
Actually, I was sort of expecting that you’d find something in the literature somewhere. I, too, am surprised to find that this is new ground.
Yes, it probably would indeed save a few moves if black were to put most of his pieces on squares the white pieces eventually need to move to anyway. As it is, black is spending most of his time fiddling while white burns.
I wonder if there are positions satisfying the original question where the black king is anywhere other than h8, h7, a8, or a7. Somehow I doubt it.
Bill Smythe
Seven pawn captures are needed.
Twelve pawn captures are needed.
In a variation on the original this can be done with only five pawn captures.
Then there is this one
Eight pawn captures are needed.
The last moves were gxf6+ Kf8
And this one
Nine pawn captures are needed.
The last moves were fxe6+ Ke8
And this requires only four pawn captures.
And only seven pawn captures are needed here.
That would require only four pawn captures, no? h4xg5xf6 and g4xf5xe6.
Or, just to make it still more elegant, how about h4xg5xf6 e.p. and g4xf5xe6 e.p.
Regardless of pawn captures, I’m guessing all of your submissions require fewer moves than my original.
Bill Smythe
I may not be able to count correctly but I particularly like the one with the Black king on e8. When I considered blocking in a bishop and putting a knight two square from the king I realized that f8 and e8 could be done that way and those were positions where either player could have moved last and it was still stalemate either way. I also have a version with the White king on c8.
Here’s one with the Black king on d8 and the White king on b7. Ten pawn captures are needed. The last moves were exd6+ Kd8.
With an eleventh pawn capture the d3 pawn can be placed on c5 and the resulting position can be a box-like as 17 pieces can get.
Congratulations! It’s too bad 17 is a prime number.
All we need now is a program that can generate a proof game for any such position.
Bill Smythe
Put the d3 pawn on c5, put the d4 pawn on d2.
The preceding moves were (say) 0.e5xd6+ Kd8
and now 1.d2-d4 stalemate.
You don’t need the d4 pawn on d2.
White’s last move could have been e6xQd7
If the Black king is already on d8 then Black is stalemated. If the Black king was on e8 then the capture was check and Kd8 stalemates White.