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1.  SwissGambit
Caninus Interruptus
12 Dec '13 20:11
So maybe the 23.5'er I posted is a tad difficult.

D. Innocenti, 1990
Position after white's 12th move. How did the game go?
2.  byedidia
Mister Why
14 Dec '13 00:47
There are at least 11 moves that we know black had to have made: Not necessarily in this order.

d-pawn moved
Knight b8-c6-d4-f5 (that's three)
Be6
Qd7
0-0-0
Qc8
Rc-g8-g3-f3 (that's three)

That leaves no moves to play with for black.

Somehow before the Rook got loose, he had to have lost the kingside bishop, knight and knight-pawn without their having moved. One of Black's moves had to have been a capture of the g pawn. Probably Rg3.

Given that the dark square bishop is gone, and it never moved, and the White DSB never moved it was probably a knight that did the deed.

I cannot make the knight tour in less than 13 moves and I still need to push the pawn a square, so I'm stumped for the moment.
3.  SwissGambit
Caninus Interruptus
14 Dec '13 00:50
Originally posted by byedidia
There are at least 11 moves that we know black had to have made: Not necessarily in this order.

d-pawn moved
Knight b8-c6-d4-f5 (that's three)
Be6
Qd7
0-0-0
Qc8
Rc-g8-g3-f3 (that's three)

That leaves no moves to play with for black.

Somehow before the Rook got loose, he had to have lost the kingside bishop, knight and knight-pawn without thei ...[text shortened]... in less than 13 moves and I still need to push the pawn a square, so I'm stumped for the moment.
That's the general idea - you count the minimum number of moves and go from there.

You can get an R to f3 in only 2 moves (Rd8-d3, f3) and an N to f5 in only 2 (Nh6-f5). That may start some new trains of thought.
4.  byedidia
Mister Why
14 Dec '13 01:14
Right, I hadn't noticed that the king also moved from 0-0-0 and I had the rook on the wrong square.
5. 14 Dec '13 03:32 / 2 edits
That's also a tad difficult. I can't do it in less than 13 moves for white. 1 pawn move, 10 knight moves around the board plus two more waiting for black to get into position.

To solve the problem black has to make 10 piece moves and 1 pawn move, I think. I can't do it without 4 moves for the black knight, making 12 in total.
6. 14 Dec '13 09:16
My solution:

1. Nf3 Nh6 2. Ne5 Nf5 3. Nxd7 Nxd7 4. g4 Nf6 5. g5 Be6 6. gxf6 Qd7 7. fxg7 O-O-O 8. gxf8=N Kb8 9. Ng6 Qc8 10. Nf4 Rd3 11. Nh3 Rf3 12. Ng1
7. 14 Dec '13 15:41
Originally posted by Sebastian Yap
My solution:

1. Nf3 Nh6 2. Ne5 Nf5 3. Nxd7 Nxd7 4. g4 Nf6 5. g5 Be6 6. gxf6 Qd7 7. fxg7 O-O-O 8. gxf8=N Kb8 9. Ng6 Qc8 10. Nf4 Rd3 11. Nh3 Rf3 12. Ng1
Brilliant!
8. 14 Dec '13 15:48
Looks like you have it.

9.  SwissGambit
Caninus Interruptus
14 Dec '13 22:27 / 1 edit
SOLV'D

That is known as the Pronkin theme.

A Pronkin is when a promoted piece goes to a home square of that same type of piece.
10. 15 Dec '13 00:25
Lovely puzzle.

Out of interest can computers handles compositions such as this? Whilst the only moves it would take extraordinary power to merely number crunch.
11.  SwissGambit
Caninus Interruptus
15 Dec '13 18:41 / 1 edit
Originally posted by Habeascorp
Lovely puzzle.

Out of interest can computers handles compositions such as this? Whilst the only moves it would take extraordinary power to merely number crunch.
Yes, computers can solve most Proof Games. The programmer has to add some heuristics, like counting the minimal number of moves for each possible routing of pieces that reaches the position. The computer can then disregard any moves exceeding the allotted total for a specific piece.