Author: Dann Corbit
Date: 11:40:09 12/10/99
Go up one level in this thread
On December 10, 1999 at 03:00:04, Paulo Soares wrote:
>On December 09, 1999 at 20:14:01, Dann Corbit wrote:
>
>>On December 09, 1999 at 18:45:42, Paulo Soares wrote:
>>>I think that are some lines that programs can't see even at
>>>depth 20.
>>Absolutely. Any move where the "payoff" is 10 full moves ahead will take 20
>>plies to see. And if the payoff is farther, the computer may not make the right
>>choice until the move is seen. Often, however, there is a simple reason why a
>>choice was not seen. More often than not when the computer analysis is deep
>>enough to see the benefit drawn in the human analysis, one of the following
>>problems exists:
>>{calling the position with a clear benefit the final board position:}
>>0. The final board position requires an intermediate positional move.
>>1. The final board position requires a deep sacrifice.
>>2. There is a zugzwang position between the final board position and the
>>current position.
>>3. The stated move is wrong {happens more often than you might think}.
>
>Look for the line below, possibly the best, or less bad, for black. After 14
>plies I placed Rebel Century (it could be another program ) to analyze the
>position, you can see that the evaluation is low.
>White wins this position, but in what item(0,1,2 or3)would you place the
>position?
>
>1. Bxh7+ Kxh7 2. Qh5+ Kg8 3. Rg3 Bf8 4. Bg5 Qc8 5. Rc1 (5. Bf6 Qc2!?) 5...
>Nc6 6. Bf6 Nxd4 7. Rxc8 Raxc8
>
>Position after 7....Raxc8:
>2r1rbk1/1p3pp1/p3pB2/3pP2Q/P2n4/6RP/1P3PP1/6K1 w - - 0 8
>
>PIII-450, HT=60Mb, Default settings:
>
> +---+---+---+---+---+---+---+---+ ComeDann
>8 | | | *R| | *R| *B| *K| |
> +---+---+---+---+---+---+---+---+ 00:00:00 00:00:00
>7 | | *p| | | | *p| *p| |
> +---+---+---+---+---+---+---+---+
>6 | *p| | | | *p| B | | | Time infinite
> +---+---+---+---+---+---+---+---+ Hash 60 Mb
>5 | | | | *p| p | | | Q | Engine Rebel Century
> +---+---+---+---+---+---+---+---+ Personality Rebel Century
>4 | p | | | *N| | | | | anti-GM Off
> +---+---+---+---+---+---+---+---+ System Tiger Off
>3 | | | | | | | R | p | Combination Off
> +---+---+---+---+---+---+---+---+ Style Normal
>2 | | p | | | | p | p | | Strength Strongest
> +---+---+---+---+---+---+---+---+ Search Normal Search
>1 | | | | | | | K | |
> +---+---+---+---+---+---+---+---+
> a b c d e f g h
>
>2r1rbk1/1p3pp1/p3pB2/3pP2Q/P2n4/6RP/1P3PP1/6K1 w - -
>
>00:00:00 1.00 -0.43 1.Bxg7 Bxg7
>00:00:00 1.06 1.67 1.Rd3 gxf6 2.Rxd4
>00:00:00 1.08 1.86 1.a5
>00:00:00 1.11 2.08 1.b4
>00:00:00 2.00 1.68 1.b4 Rc2 2.Rg4 Rc4 3.Rg3 Rxb4
>00:00:00 2.05 1.71 1.b3 Rc1+ 2.Kh2
>00:00:00 3.00 1.16 1.b3 Rc1+ 2.Kh2 Nf5 3.Rg4
>00:00:00 3.01 1.19 1.b4 Rc1+ 2.Kh2 Rec8 3.f4
>00:00:00 3.02 1.41 1.f4 Rc2 2.Kh2 Rxb2
>00:00:00 3.04 1.42 1.Kh2 Nf5 2.Rg4 Rc2 3.Kg1 Rxb2
>00:00:00 3.09 1.64 1.Rg4 Rc4 2.Rg3 Rxa4
>00:00:00 4.00 1.54 1.Rg4 Nb3 2.g3 Rc2 3.f3 Rxb2
>00:00:01 5.00 1.42 1.Rg4 Nf5 2.Kh2 Rc2 3.Kg1 Rxb2
>00:00:02 6.00 1.16 1.Rg4 Nf5 2.b3 Rc1+ 3.Kh2 Rec8 4.b4
>00:00:05 7.00 1.09 1.Rg4 Nf5 2.b4 Be7 3.b5 Bxf6 4.exf6
> g6 5.bxa6 (3)
>
>00:00:08 7.12 1.14 1.Rc3 Nf5 2.Rxc8 Rxc8 3.Bg5 g6
>00:00:10 8.00 1.09 1.Rc3 Nf5 2.Bg5 Bb4 3.Rxc8 Rxc8
> 4.Qd1 Rc4 5.Qd3 (9)
>
>00:00:22 9.00 1.05 1.Rc3 Nf5 2.Bg5 Bb4 3.Rxc8 Rxc8
> 4.Qd1 a5 5.Qb3 Nd4 6.Qd3 (18)
>
>00:00:57 10.00 1.11 1.Rc3 Nf5 2.Bg5 Bb4 3.Rxc8 Rxc8
> 4.Qd1 Rc4 5.Kh2 Be7 (33)
>
>00:02:07 11.00 1.08 1.Rc3 Nf5 2.Bg5 Bb4 3.Rxc8 Rxc8
>00:06:34 12.00 1.11 1.Rc3 Nf5 2.Bg5 Bb4 3.Rxc8 Rxc8
> 4.Qd1 (196)
>
>
>Positions : 99.105.320
>Nodes per second : 131.091
>
>Extensions (checks) : 4.276.716 (4%)
>Extensions (captures) : 952.553 (0%)
>Extensions (king safety) : 354.070 (0%)
>Extensions (on depth) : 3.858.925 (3%)
>Extensions (remaining) : 403.564 (0%)
>Extensions (total) : 9.845.828 (9%)
>
>Hash Table : 1.542.248 1.193.742 (99%)
>Average depth : 13
>Deepest depth : 41
It's an interesting position.
Crafty likes Rxg7+ with an advantage of about one pawn. Here is Crafty's
analysis:
2r1rbk1/1p3pp1/p3pB2/3pP2Q/P2n4/6RP/1P3PP1/6K1 w - - acd 15; acn 116978391; acs
802; ce 94; pv Rxg7+ Bxg7 Bxg7 Kxg7 Qg4+ Kf8 Qxd4 Rc4 Qb6 Re7 Qd8+ Re8 Qd6+ Re7
b3 Rc3 Qd8+;
However, I don't think that I understand your question.
Rebel settles on Rc3 with an advantage of about one pawn in about 8 seconds and
sticks with it. It seems that both programs see a move that is hardly
dominating (and with approximately the same advantage) and stay with it from
there forward.
Do you feel that there is some dominating move that the programs seem to miss?
If so, what is it? I think I would have traded the bishop and the rook for the
bishop, the pawn and the knight because the sequence is fairly obvious and it
leaves black's king standing naked. That's just because Rebel's sequence was
way to clever for me, besides which, I get nervous when lots of my pieces are
under fire at the same time.
I have verified that there are no sure checkmates within 9 full moves.
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