Author: Johan de Koning
Date: 22:58:35 09/23/03
Go up one level in this thread
On September 23, 2003 at 03:42:18, Tim Foden wrote:
>On September 23, 2003 at 03:03:12, Johan de Koning wrote:
>
>>On September 22, 2003 at 02:32:34, Tim Foden wrote:
>>
>>>I think these positions might behave like smaller versions of the full thing...
>>>
>>>[d] 8/1pppppp1/8/8/8/8/1PPPPPP1/8 w - -
>>>
>>>GLC thinks this is a win... d4 Mate in 15.
>>
>>Hmmm..., my program (named JJ.EXE :-) proved it a draw.
>>Then I added en passent.
>>Now it says it's a mate in 14.
>>
>>098.81 75M346 D21 +4 : d4,d5 f3,b6 e4,dxe4 fxe4,b5 b4,c6 g3,f6 g4,g6 e ...
>>184.33 140M189 D23 +212 : d4,d5 f3,g6 e4,dxe4 fxe4,f5 exf5,gxf5 b4,e6 b5, ...
>>279.30 212M443 D25 +9973 : d4,d5 f3,b6 e4,dxe4 fxe4,b5 c3,e6 e5,c6 b4,f6 e ...
>>377.94 286M689 D27 +9973 : d4,d5 f3,b6 e4,dxe4 fxe4,b5 c3,c6 b3,g6 c4,bxc4 \
>> bxc4,f6 c5,e6 d5,exd5 exd5,cxd5
>>0000011111 1111222222 22222222:: :::::::::: :::::::::: :::::::::: ::::::::::
>>0357912456 7899011222 23222210:: :::::::::: :::::::::: :::::::::: ::::::::::
>>
>>So by adding e.p. I removed the 1 known bug, but we still don't agree. :-(
>>Unfortunately we don't know the number and nature of the unknown bugs. :-)
>>
>>.. Johan
>
>Well, we can probably track the bugs down...
>
>After d4 d5 GLC agrees that f3 is a mate in 13...
>
>[d]8/1pp1ppp1/8/3p4/3P4/8/1PP1PPP1/8 w
>
> 22 6.229 +Mate13 6249564 f3 g5 2. e4 e5 3. dxe5 d4 4. b4 c6 5. g3 b6 6. f4
> gxf4 7. gxf4 c5 8. f5 d3 9. cxd3 cxb4 10. e6
> fxe6 11. fxe6 b3
>
>GLC prefers g5 after f3 rather than b6.
>
>But what does yours say after d4 g5?
>
>[d]8/1ppppp2/8/6p1/3P4/8/1PP1PPP1/8 w
>
>GLC says:
>
> 22 22.202 +Mate14 21765k c4 f5 2. g3 f4 3. e4 fxe3 4. fxe3 e6 5. g4 d6 6.
> d5 exd5 7. cxd5 c6 8. dxc6 bxc6 9. e4 c5 10. b3
> d5 11. exd5 {ht}
002.86 3633954 D19 +102 : c4,f5 g3,f4 g4,b6 b4,c6 e3,f3 c5,bxc5 bxc5,d5 ...
003.46 4415449 D19 +103 : e4,b5 c3,g4 b3,d6 f4,e5 fxe5,dxe5 d5,g3 c4,b4 ...
004.29 5417281 D21 +105 : e4,b5 c3,c6 b3,g4 c4,bxc4 bxc4,d6 d5,cxd5 exd ...
005.00 6327052 D21 +9977 : c4,f5 g3,f4 g4,b6 b4,c6 e3,f3 e4,d5 exd5,cxd5 ...
005.33 6766094 D23 +9977 : c4,f5 g3,f4 g4,b6 b4,c6 e3,f3 e4,d5 exd5,cxd5 \
c5,bxc5 bxc5,e6 c6,e5
Evaluation didn't exactly help here. :-)
Anyway, that's Mate12, so it considers 1...g5 worse then 1...d5.
>or for a 1 move longer PV...
>
> 25 25.336 +Mate14 25311k c4 f5 2. g3 f4 3. e4 fxe3 4. fxe3 e6 5. g4 d6 6.
> d5 exd5 7. cxd5 c6 8. dxc6 bxc6 9. e4 c5 10. b3
> d5 11. exd5 c4
. . . . . . . . This is the end of your PV.
. . . . . . . . O-to-move has a runner at d5, which wins in 5 ply.
. . . . . . . . So that adds up to Mate14 all right.
. . . o . . x . BUT ...
. . x . . . o . That Mate14 is a heurstic lower bound, not a perfect score.
. o . . . . . . The true score is of course bxc4#.
. . . . . . . . In other words, you can use heurstic bounds to prune against
. . . . . . . . beta (or alpha), but not inside the window.
BTW, my program is much faster than yesterday. Mostly because of using the
TT move for sorting. But I think I've implemented all the standard tricks that
come with AlphaBeta, and I'm running out of non-standard ideas as well.
I'm sure the code (and data!) can easily be optimized to run 2x or 3x faster,
but that's rather pointless as long as there are no tournamtents to play.
It would still be fun though. :-)
But for today I'll let it burn some CPU on the d4d5 and 7-7 positions.
... Johan
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