Author: Richard Pijl
Date: 01:42:01 11/23/05
Go up one level in this thread
On November 23, 2005 at 00:27:22, Will Singleton wrote:
>[d]5r1k/1pq4p/p3Q3/8/6R1/7P/6P1/6K1 b - -
>
>This position illustrates two effects of differing methods of rep draw scoring.
>The first method is used by many programs, including (apparently) Fruit, in
>which the program scores a position found in the search that is equal to one in
>the game history as a draw. This method ignores the fact that making the move
>which gives 0.00 does not actually constitute a draw, and the game can continue
>with any score possible.
>
>The second method is to assign a draw score only to those positions reached in
>the search or the game history that actually represent real draws. The problem
>here is that the program, due to horizon effects or other circumstances I don't
>fully understand, will choose to play a useless repetition before making the
>move which it could have (should have) played in the first place. Problems here
>include wasting time, plus sometimes incorrectly assessing the rep draw, plus
>looking kinda stupid.
The Baron uses a combination of both: On a repetition that happens in search
(including root position), the Baron scores that repetition immediately as 0,
but when including the full game history, it requires a second repetition before
a drawscore is returned. That allows the program to repeat a position to try
another continuation without showing repetitions in the PV before doing
something useful.
>In the above position, black should probably play Qd8. But my program, being a
>"second method" program, somehow likes the line Qc1+ Kh2 Qc7+ Kg1 and then Qd8.
>If you analyse with Fruit, it gives a draw score after the rep, which is fairly
>silly since it has to admit its error after Qd8. But which is sillier, Fruit's
>error or Amateur's? And, for those who subscribe to method 2, will your program
>duplicate Amateur's pseudo-rep or play Qd8 directly?
The Baron's suggestion looks weird and perhaps requires looking into my passed
pawn scoring:
ply time nodes score pv
6(15). 0:00.41 111982 +0.91 Qc7-f7 Qe6-e5 Qf7-f6 Qe5-g3 b7-b5
Kg1-h2 (Qf6-f2)
7(15)& 0:00.52 146858 +0.70 Qc7-f7 Qe6-e5 Qf7-f6 Qe5-g3 b7-b5
Kg1-h2 Qf6-f1 (Qg3-e5)
7(15)& 0:01.31 368173 +0.72 a6-a5 Qe6-e3 Rf8-d8 Qe3-e1 Qc7-b6
Kg1-h1 Qb6-f6 Qe1xa5 Qf6-f1 Kh1-h2 (Rd8-d3
)
7(17)& 0:02.30 644024 +0.84 b7-b6 Qe6-e1 Qc7-f7 Kg1-h2 a6-a5
Qe1-g3 (Qf7-f2)
7(17). 0:02.38 670744 +0.84 b7-b6 Qe6-e1 Qc7-f7 Kg1-h2 a6-a5
Qe1-g3 (Qf7-f2)
8(16)& 0:03.41 992953 +0.62 b7-b6 Qe6-e2 Qc7-c5 Kg1-h1 Qc5-b5
Qe2-e6 Qb5-f1 Kh1-h2 b6-b5 Qe6-h6
8(16)& 0:03.66 1077799 +0.68 Qc7-f7 Qe6-e5 Qf7-f6 Qe5-g3 b7-b6
Kg1-h2 b6-b5 Rg4-g5 (Qf6-f1) (Rg5-h5)
8(19). 0:05.16 1525906 +0.68 Qc7-f7 Qe6-e5 Qf7-f6 Qe5-g3 b7-b6
Kg1-h2 b6-b5 Rg4-g5 (Qf6-f1) (Rg5-h5)
9(17)& 0:05.80 1744213 +0.68 Qc7-f7 Qe6-b6 Qf7-e7 Qb6-b2 Rf8-f6
Qb2-c3 b7-b5 Rg4-f4 Kh8-g7 Qc3-g3
9(21)& 0:08.22 2520636 +0.95 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-b6 (Qe5xg3)
9(21). 0:08.67 2646398 +0.95 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-b6 (Qe5xg3)
10(21)& 0:10.67 3309866 +0.95 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-b6 Qe5xg3
(Qb6xd8) (Kh8-g7)
10(21). 0:14.59 4464603 +0.95 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-b6 Qe5xg3
(Qb6xd8) (Kh8-g7)
11(23)& 0:23.44 7364256 +1.00 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-h6 Qe5xg3
Qh6-f6 (Kh8-g8) (Qf6xd8) (Kg8-g7)
11(23). 0:26.17 8272199 +1.00 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-h6 Qe5xg3
Qh6-f6 (Kh8-g8) (Qf6xd8) (Kg8-g7)
12(22)& 0:45.63 14783153 +1.00 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-h6 Qe5xg3
Qh6-f6 Kh8-g8 Qf6xd8 (Kg8-f7) (Qd8-d7)
12(22). 0:59.05 19534318 +1.00 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-h6 Qe5xg3
Qh6-f6 Kh8-g8 Qf6xd8 (Kg8-f7) (Qd8-d7)
13(26)& 2:33.40 50783819 +0.90 b7-b5 h3-h4 a6-a5 Qe6-d5 Qc7-c1
Kg1-h2 Qc1-b2 Rg4-g5 a5-a4 Qd5xb5 Qb2xb5
Rg5xb5 Rf8-a8 Rb5-b2
13(26). 4:12.26 81686481 +0.90 b7-b5 h3-h4 a6-a5 Qe6-d5 Qc7-c1
Kg1-h2 Qc1-b2 Rg4-g5 a5-a4 Qd5xb5 Qb2xb5
Rg5xb5 Rf8-a8 Rb5-b2
14(31)& 6:33.43 130496248 +0.60 b7-b5 Qe6xa6 Qc7-c5 Kg1-h2 Qc5-e5
Kh2-g1 Rf8-d8 Rg4-g3 b5-b4 Qa6-f1 Rd8-a8
Qf1-f3 Ra8-b8 Qf3-b3 Qe5-e1 Kg1-h2
14(31)& 16:49.00 320167456 +0.82 Qc7-d8 Qe6-b3 b7-b6 Qb3-e6 a6-a5
(Kg1-h2) (Qd8-c7) (Kh2-g1) (b6-b5)
(Qe6-e3) (Rf8-d8)
(Qe3-e1) (Qc7-b6) (Kg1-h1) (Qb6-f6)
(Qe1xa5) (h7-h5)
14(31). 17:02.74 324589359 +0.82 Qc7-d8 Qe6-b3 b7-b6 Qb3-e6 a6-a5
(Kg1-h2) (Qd8-c7) (Kh2-g1) (b6-b5)
(Qe6-e3) (Rf8-d8)
(Qe3-e1) (Qc7-b6) (Kg1-h1) (Qb6-f6)
(Qe1xa5) (h7-h5)
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