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Subject: Re: Is this solvable by brute force? (Example of 57-ply game)

Author: Edward Seid

Date: 09:08:23 09/18/03

Go up one level in this thread


On September 18, 2003 at 11:25:01, Ricardo Gibert wrote:

>On September 18, 2003 at 10:02:33, Edward Seid wrote:
>
>>2- the longest 'game' is certainly less than 81 ply, and is probably around
>>60-65 (81 ply is calculated by the impossible scenario of each side taking 40
>>ply each to march all pawns to the 7th rank + 1 ply to promote)
>
>Unless I've suffered from a brain fart, a 42 ply game is impossible, while a 41
>ply game is trivial to construct.

I think you're confusing 'ply' and 'move'.  One move = 2 ply.


Just for kicks, I've constructed the following 57-ply game.  Perhaps this is the
longest possible Pawn game?

Pawn Game - 57 ply

1.a3 a6 2.a4 a5 3.b3 b6 4.b4 b5 5.c3 c6 6.c4 c5 7.d3 d6 8.d4 d5 9.e3 e6 10.e4 e5
11.f3 f6 12.f4 f5 13.g3 g6 14.g4 g5 15.h3 h6 16.h4 h5 17.bxa5 bxa4 18.dxc5 dxc4
19.fxe5 fxe4 20.hxg5 hxg4 21.a6 a3 22.a7 a2 23.c6 c3 24.c7 c2 25.e6 e3 26.e7 e2
27.g6 g3 28.g7 g2 29.a8Q+ 1-0


Also for kicks, I've calculated the game tree based on the number of possible
moves at each position in the above game.

16 16
15 15
14 14
13 14
14 14
13 14
14 14
14 14
14 14
13 14
14 14
14 14
14 14
13 13
14 14
13 14
14 13
11 10
 8  7
 5  5
 4  4
 4  4
 4  4
 4  4
 4  4
 4  4
 4  4
 4  4
 4

16^2 * 15^2 * 14^23 * 13^7 * 11 * 10 * 8 * 7 * 5^2 * 4^17 = 2.2x10^54 (!!)
Did I just bite off more than I can chew??



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