Author: Dann Corbit
Date: 19:23:44 03/29/02
Go up one level in this thread
On March 29, 2002 at 22:01:40, Will Singleton wrote:
>On March 29, 2002 at 16:39:53, Dann Corbit wrote:
>
>>On March 29, 2002 at 15:54:08, Art Basham wrote:
>>
>>>Here white's best move is Bg7..!
>>>(with the threat of 2. Qxh7+...and mate by the rook at h8...
>>>
>>>
>>>[D]1r2r1k1/3b1p1p/p4PpB/2qPp3/p1P1R2Q/P7/6PP/5R1K w - -
>>>
>>>Believe it or not, some engines miss this completely and rather play
>>>something like Bc1..etc. ???
>>
>>Beowulf took 14.5 seconds on an AMD 950 MHz machine.
>>
>>Position 1 - White to play
>>--------------------------
>>ID =
>>FEN = 1r2r1k1/3b1p1p/p4PpB/2qPp3/p1P1R2Q/P7/6PP/5R1K w - -
>>
>>. r . . r . k .
>>. . . b . p . p
>>p . . . . P p B
>>. . q P p . . .
>>p . P . R . . Q
>>P . . . . . . .
>>. . . . . . P P
>>. . . . . R . K
>>
>>Current Position = 0.58
>>Number of Possible Moves = 36
>>
>> 6 98 88 79497 Bc1 a5 Qf2 Rec8 Qxc5 Rxc5
>> 7 118 184 180300 Bc1 h5 Qf2 Rbc8 Bb2 Bf5 Qxc5 Rxc5
>> 8 94 396 420473 Bc1 h5 Qf2 Qxf2 Rxf2 Bf5 Rh4 e4
>> 9 113 1038 1110972 Bc1 h5 Qg5 Rb3 Qh6 Qf8 Qxf8+ Kxf8 c5 Rd3
>> 9 123! 1448 1555074 Bg7 h5 Qg5 Rb3 Qh6 Qb6 Rfe1 Rb1 Rxb1 Qxb1+
>> 9 588 2554 2711402 Bg7 Bg4 Rxg4 h5 Ra1 Qxa3 Qe1 Qc5 Rxa4 hxg4
>> 10 586 4907 5283324 Bg7 h5 Qg5 Qf2 Ree1 Qc5 Qg4 hxg4 d6
>> 11 603 9748 10947729 Bg7 Bg4 Rxg4 h5 Qg5 Qf2 Qc1 Qe2 Rh4 Rb2 g3 Qd3
>>Rf2
>>
>>Search Time : 999.0 Seconds
>>Total Nodes Searched : 95521440 (84.8% Qui)
>>Total Nodes Evaluated : 80995522
>>Cuts : Delta 19222644 : SEE 9400726 : Mate 0
>> : Razor 5045011 : Eval 43111935
>>Extensions : Check 3669449 : OneRep 631520 : CMThreat 119043
>> : Pawn 560266 : Recap 296138 : RevCheck 244444
>>Hash Stores (Size) : 6014980 (2097143)
>>Hash Probes (Hits) : 55812193 (4685047)
>>EGTB Probes (Hits) : 0 (0)
>>Move Ordering : 55.4%
>>Best Move = Bg7
>>--Answer: Bg7 ** Correct **
>>Time To Solution = 14.48 sec
>>Correct So Far : 1/1
>
>
>Amateur does well here, probably by luck. Finds Bg7 at ply 4 after 0.12 sec,
>score +2, rising to +6 at ply 9, powerbook 300mhz.
>
>btw, a question re your node numbers. Beowulf reports 95 million total nodes,
>but shows only 10 million in ply 11? I assume you just omitted ply 12.
It's the count where it was interrupted (probably near to completing 12 ply).
>And, the quiesce percentage seems high, although I notice some programs report
>high percentages, and some low. I'm thinking this is due to how nodes are
>counted. Does Beowulf happen to count qnodes as calls to quiesce, even if the
>quiesce search cuts off prior to making a move?
Qnodes is incremented for every call to quiesce.
/* --------------==== QUIESCENCE SEARCH ====------------ */
/* Do the quiescence search. This is a clever trick used by ALL chess programs
* avoid the so-called 'Horizon Effect'. This is where a terrible capture is pu
* off the end of the search tree and therefore missed. The quiescence search s
* continues the search and only evaluates the board when all is quiet and calm.
* In the Quiescence search, we continue the a-b tree search, but consider only
* moves. If we find ourselves in check here then we simply ignore it and just
* generate captures anyway. At each point we allow ourselves the choice of mak
* no move at all (on the expectation that there might be a better move which is
* NOT a capture, so therefore *forcing* a capture might give spurious results.)
int Quiesce(Board * B, const int alpha, const int beta, int ply, int
{
int NMoves,
Moveno,
newfifty = fifty,
gchk = 0;
MOVE movelist[MAX_MOVES],
m,
*lastmove,
hashmove = NO_MOVE,
bestmove = NO_MOVE;
int score,
best,
talpha = alpha,
tbeta = beta,
EntryScore;
FullMove Full[100];
HashElt *Entry;
BOOL IsPV = FALSE,
Filtered = FALSE;
Undo U;
/* Increase the Node Count */
Qnodes++;
/* Check for draw */
if (IsDrawn(B, ply, fifty, FALSE))
return ((Current_Board.side == B->side) ? (DRAW_SCORE) : -(DRAW_SCORE));
...
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