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REPORT: wrong perft result by qperft.

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Jesús Muñoz

Joined: 13 Jul 2011
Posts: 689
Location: Madrid, Spain.

Post subject: REPORT: wrong perft result by qperft. Posted: Tue Feb 14, 2012 3:47 pm

Hello:

Sorry for this extremely long post.

[d]rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 6

I was testing this position for see if JetChess 1.0.0.0 and/or qperft (by Muller, but this time compiled my myself with mingw32) had problems with O-O for white: there is no problem here until Perft(6), (both results match). But I found one flaw in (at least) one of these two perft counters at Perft(7) (256 MB of hash for each perft counter):

Code:

qperft 7 "H24" "rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 6"
Hash-table size = ffffff, Starts at 4f0040,section = 1fffff
- - - - - - - - - - - -
- - - - - - - - - - - -
- - r n b q k b . r - -
- - p p . p . p p p - -
- - . . p . . . . . - -
- - . . . . P . . . - -
- - . . B . . . . . - -
- - . . . . . . . . - -
- - P P P . N n P P - -
- - R N B Q K . . R - -
- - - - - - - - - - - -
- - - - - - - - - - - -

Quick Perft by H.G. Muller
Perft mode: Hash-table size = 256MB, bulk counting in horizon nodes

perft( 1)= 42 ( 0.000 sec)
perft( 2)= 1352 ( 0.000 sec)
perft( 3)= 53392 ( 0.000 sec)
perft( 4)= 1761505 ( 0.031 sec)
perft( 5)= 70202861 ( 0.735 sec)
perft( 6)= 2362704901 (13.078 sec)
perft( 7)= 94855003088 (358.000 sec)

Code:

rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 6

1 Qd1-d2 2481769422
2 Qd1-d3 3719739001
3 Qd1-d4 3598056747
4 Qd1-d5 2815305249
5 Qd1-d6 2314600161
6 Qd1*d7 207937563
7 Rh1-g1 1983977646
8 Rh1-f1 2220729699
9 Bc1-d2 2107363662
10 Bc1-e3 3184524390
11 Bc1-f4 2482656228
12 Bc1-g5 2400385594
13 Bc1-h6 2344263758
14 Bc4-b5 2130713616
15 Bc4-a6 1855061374
16 Bc4-d5 2046941872
17 Bc4-e6 2444185312
18 Bc4*f7 86568355
19 Bc4-d3 1886965922
20 Bc4-b3 1816240296
21 Nb1-a3 2002068159
22 Nb1-c3 2655487727
23 Nb1-d2 1435627351
24 Ne2-c3 3057530890
25 Ne2-d4 3061284388
26 Ne2-f4 2949871106
27 Ne2-g3 2865273204
28 Ne2-g1 2354927176
29 a2-a3 2245837704
30 a2-a4 2548648372
31 b2-b3 2166557328
32 b2-b4 2263311424
33 c2-c3 2411002727
34 g2-g3 1981011243
35 g2-g4 2033046400
36 h2-h3 2217212927
37 h2-h4 2387827889
38 e5-e6 2461806026
39 0-0 2291266832
40 Ke1-f1 2483161986
41 Ke1-d2 1152858513
42 Ke1*f2 1701268892

Total: 94854874131

94,854,874,131 (move pathes after 7 half moves).

Time: 380.995 s (0:06:20.995).

Splitting the results in qperft:

Code:

2. e1g1 moves = 2291266832 (10.625 sec)
2. h2h3 moves = 2217212927 (13.391 sec)
2. h2h4 moves = 2387827889 (14.125 sec)
2. g2g3 moves = 1981011243 (11.062 sec)
2. g2g4 moves = 2033046400 (11.328 sec)
2. c2c3 moves = 2411002727 (11.422 sec)
2. b2b3 moves = 2166557328 (10.844 sec)
2. b2b4 moves = 2263311424 (11.141 sec)
2. a2a3 moves = 2245837704 (10.765 sec)
2. a2a4 moves = 2548648372 (11.703 sec)
2. e5e6 moves = 2461934981 (11.125 sec)
2. b1a3 moves = 2002068159 (10.047 sec)
2. b1c3 moves = 2655487727 (10.250 sec)
2. b1d2 moves = 1435627351 ( 5.594 sec)
2. e2c3 moves = 3057530890 (13.375 sec)
2. e2d4 moves = 3061284388 (12.719 sec)
2. e2f4 moves = 2949871106 (13.500 sec)
2. e2g3 moves = 2865273204 (12.797 sec)
2. e2g1 moves = 2354927176 (11.562 sec)
2. c4b5 moves = 2130713616 ( 9.625 sec)
2. c4a6 moves = 1855061374 ( 7.344 sec)
2. c4d3 moves = 1886965922 ( 6.500 sec)
2. c4d5 moves = 2046941872 ( 7.484 sec)
2. c4e6 moves = 2444185312 (11.188 sec)
2. c4f7 moves = 86568355 ( 0.922 sec)
2. c4b3 moves = 1816240298 ( 7.156 sec)
2. c1d2 moves = 2107363662 ( 6.969 sec)
2. c1e3 moves = 3184524390 (12.718 sec)
2. c1f4 moves = 2482656228 ( 8.297 sec)
2. c1g5 moves = 2400385594 (10.422 sec)
2. c1h6 moves = 2344263758 (10.469 sec)
2. d1d2 moves = 2481769422 ( 9.844 sec)
2. d1d3 moves = 3719739001 (11.843 sec)
2. d1d4 moves = 3598056747 (11.719 sec)
2. d1d5 moves = 2815305249 ( 8.469 sec)
2. d1d6 moves = 2314600161 ( 7.484 sec)
2. d1d7 moves = 207937563 ( 2.891 sec)
2. h1g1 moves = 1983977646 ( 3.609 sec)
2. h1f1 moves = 2220729699 ( 4.172 sec)
2. e1f1 moves = 2483161986 ( 3.469 sec)
2. e1f2 moves = 1701268892 ( 5.578 sec)
2. e1d2 moves = 1152858513 ( 4.688 sec)

perft( 7)= 94855003088 (390.235 sec)

JetChess and qperft do not agree (128,957 nodes more in qperft):

Code:

[Nodes(qperft)] - [nodes(JetChess)] =

= 128,955 (e6)
= 2 (Bb3)

The comparison was made by eye.... I hope no errors.

Only change in qperft source was replacing %10lld by %10I64d and %12lld by %12I64d. Reasons for these changes:

http://talkchess.com/forum/viewtopic.php?topic_view=threads&p=425310&t=40108

http://talkchess.com/forum/viewtopic.php?topic_view=threads&p=425312&t=40108

I did some dirty job, searching for the errors:

Code:

(JetChess 1.0.0.0): e6 played (128 MB of hash).

rnbqkb1r/pp1p1ppp/2p1P3/8/2B5/8/PPP1NnPP/RNBQK2R b KQkq - 0 6

1 qd8-c7 80381152
2 qd8-b6 78384048
3 qd8-a5 21945709
4 qd8-e7 62217713
5 qd8-f6 91231153
6 qd8-g5 105270469
7 qd8-h4 83720856
8 rh8-g8 74139349
9 bf8-e7 75419103
10 bf8-d6 96107199
11 bf8-c5 88600632
12 bf8-b4 15650634
13 bf8-a3 83712650
14 nf2*d1 42513258
15 nf2*h1 46660634
16 nf2-d3 7357733
17 nf2-e4 75283737
18 nf2-g4 67607241
19 nf2-h3 56792704
20 nb8-a6 82211968
21 c6-c5 65250953
22 a7-a6 70418560
23 a7-a5 77371240
24 b7-b6 72566559
25 b7-b5 76728327
26 d7-d6 67036802
27 d7-d5 82257295
28 d7*e6 86701509
29 f7-f6 54438728
30 f7-f5 64186383
31 f7*e6 64535721
32 g7-g6 78034448
33 g7-g5 66169827
34 h7-h6 74322298
35 h7-h5 78705132
36 ke8-e7 47874302

Total: 2461806026

2,461,806,026 (move pathes after 6 half moves).

Time: 11.574 s (0:00:11.574).

Code:

qperft 6 "H23" "-2" "rnbqkb1r/pp1p1ppp/2p1P3/8/2B5/8/PPP1NnPP/RNBQK2R b KQkq - 0 6"
Hash-table size = 7fffff, Starts at 4f0040,section = fffff
- - - - - - - - - - - -
- - - - - - - - - - - -
- - r n b q k b . r - -
- - p p . p . p p p - -
- - . . p . P . . . - -
- - . . . . . . . . - -
- - . . B . . . . . - -
- - . . . . . . . . - -
- - P P P . N n P P - -
- - R N B Q K . . R - -
- - - - - - - - - - - -
- - - - - - - - - - - -

Quick Perft by H.G. Muller
Perft mode: Hash-table size = 128MB, bulk counting in horizon nodes

2. c6c5 moves = 65256159 ( 0.610 sec)
2. h7h6 moves = 74327157 ( 0.718 sec)
2. h7h5 moves = 78710388 ( 0.750 sec)
2. g7g6 moves = 78039114 ( 0.703 sec)
2. g7g5 moves = 66173473 ( 0.610 sec)
2. f7e6 moves = 64535721 ( 0.547 sec)
2. f7f6 moves = 54441466 ( 0.468 sec)
2. f7f5 moves = 64191163 ( 0.547 sec)
2. d7e6 moves = 86701509 ( 0.735 sec)
2. d7d6 moves = 67046267 ( 0.515 sec)
2. d7d5 moves = 82266683 ( 0.672 sec)
2. b7b6 moves = 72570447 ( 0.500 sec)
2. b7b5 moves = 76734004 ( 0.563 sec)
2. a7a6 moves = 70423024 ( 0.453 sec)
2. a7a5 moves = 77376491 ( 0.500 sec)
2. f2d3 moves = 7357733 ( 0.078 sec)
2. f2e4 moves = 75289295 ( 0.469 sec)
2. f2g4 moves = 67612137 ( 0.375 sec)
2. f2h3 moves = 56797036 ( 0.297 sec)
2. f2h1 moves = 46664359 ( 0.265 sec)
2. f2d1 moves = 42517678 ( 0.297 sec)
2. b8a6 moves = 82217426 ( 0.422 sec)
2. d8e7 moves = 62217717 ( 0.281 sec)
2. d8f6 moves = 91234424 ( 0.453 sec)
2. d8g5 moves = 105274408 ( 0.469 sec)
2. d8h4 moves = 83723867 ( 0.406 sec)
2. d8c7 moves = 80384080 ( 0.250 sec)
2. d8b6 moves = 78387062 ( 0.344 sec)
2. d8a5 moves = 21945709 ( 0.109 sec)
2. f8e7 moves = 75419070 ( 0.344 sec)
2. f8d6 moves = 96110664 ( 0.406 sec)
2. f8c5 moves = 88603987 ( 0.344 sec)
2. f8b4 moves = 15650634 ( 0.094 sec)
2. f8a3 moves = 83715833 ( 0.328 sec)
2. h8g8 moves = 74144265 ( 0.109 sec)
2. e8e7 moves = 47874382 ( 0.094 sec)
perft( 6)= 2461934832 (15.125 sec)

Code:

All this math was done by hand, so may contain errors:

[Nodes(qperft)] - [nodes(JetChess)] = 128,806

c5: 5,206
h6: 4,859
h5: 5,256
g6: 4,666
g5: 3,646
fxe6: 0
f6: 2,738
f5: 4,780
dxe6: 0
d6: 9,465
d5: 9,388
b6: 3,888
b5: 5,677
a6: 4,464
a5: 5,251
Nd3: 0
Ne4: 5,558
Ng4: 4,896
Nh3: 4,332
Nxh1: 3,725
Nxd1: 4,420
Na6: 5,458
Qe7: 4
Qf6: 3,271
Qg5: 3,939
Qh4: 3,011
Qc7: 2,928
Qb6: 3,044
Qa5: 0
Be7: -33
Bd6: 3,465
Bc5: 3,355
Bb4+: 0
Ba3: 3,183
Rg8: 4,916
Ke7: 80

--------------------------------------------------

Code:

(JetChess 1.0.0.0): Bb3 played (128 MB of hash).

rnbqkb1r/pp1p1ppp/2p5/4P3/8/1B6/PPP1NnPP/RNBQK2R b KQkq - 1 6

1 qd8-c7 54525077
2 qd8-b6 58096159
3 qd8-a5 13505005
4 qd8-e7 53302902
5 qd8-f6 70060805
6 qd8-g5 73090912
7 qd8-h4 67702711
8 rh8-g8 57085208
9 bf8-e7 60529998
10 bf8-d6 68409266
11 bf8-c5 68305577
12 bf8-b4 12613053
13 bf8-a3 65315697
14 nf2*d1 31840592
15 nf2*h1 35327507
16 nf2-d3 5037855
17 nf2-e4 58142514
18 nf2-g4 51764063
19 nf2-h3 43315381
20 nb8-a6 63977245
21 c6-c5 52391837
22 a7-a6 53685043
23 a7-a5 59377653
24 b7-b6 56117504
25 b7-b5 60985564
26 d7-d6 74907507
27 d7-d5 73250093
28 f7-f6 53848827
29 f7-f5 57438047
30 g7-g6 60001019
31 g7-g5 50604958
32 h7-h6 57272220
33 h7-h5 60840404
34 ke8-e7 33572093

Total: 1816240296

1,816,240,296 (move pathes after 6 half moves).

Time: 9.490 s (0:00:09.490).

Code:

qperft 6 "H23" "-2" "rnbqkb1r/pp1p1ppp/2p5/4P3/8/1B6/PPP1NnPP/RNBQK2R b KQkq - 1 6"
Hash-table size = 7fffff, Starts at 4f0040,section = fffff
- - - - - - - - - - - -
- - - - - - - - - - - -
- - r n b q k b . r - -
- - p p . p . p p p - -
- - . . p . . . . . - -
- - . . . . P . . . - -
- - . . . . . . . . - -
- - . B . . . . . . - -
- - P P P . N n P P - -
- - R N B Q K . . R - -
- - - - - - - - - - - -
- - - - - - - - - - - -

Quick Perft by H.G. Muller
Perft mode: Hash-table size = 128MB, bulk counting in horizon nodes

2. c6c5 moves = 52391837 ( 0.516 sec)
2. h7h6 moves = 57272220 ( 0.578 sec)
2. h7h5 moves = 60840404 ( 0.594 sec)
2. g7g6 moves = 60001019 ( 0.578 sec)
2. g7g5 moves = 50604958 ( 0.484 sec)
2. f7f6 moves = 53848827 ( 0.454 sec)
2. f7f5 moves = 57438047 ( 0.500 sec)
2. d7d6 moves = 74907507 ( 0.593 sec)
2. d7d5 moves = 73250093 ( 0.625 sec)
2. b7b6 moves = 56117504 ( 0.422 sec)
2. b7b5 moves = 60985564 ( 0.453 sec)
2. a7a6 moves = 53685043 ( 0.375 sec)
2. a7a5 moves = 59377653 ( 0.407 sec)
2. f2d3 moves = 5037855 ( 0.062 sec)
2. f2e4 moves = 58142514 ( 0.375 sec)
2. f2g4 moves = 51764063 ( 0.313 sec)
2. f2h3 moves = 43315381 ( 0.250 sec)
2. f2h1 moves = 35327507 ( 0.218 sec)
2. f2d1 moves = 31840592 ( 0.235 sec)
2. b8a6 moves = 63977245 ( 0.359 sec)
2. d8e7 moves = 53302902 ( 0.266 sec)
2. d8f6 moves = 70060805 ( 0.297 sec)
2. d8g5 moves = 73090912 ( 0.343 sec)
2. d8h4 moves = 67702711 ( 0.360 sec)
2. d8c7 moves = 54525077 ( 0.203 sec)
2. d8b6 moves = 58096159 ( 0.281 sec)
2. d8a5 moves = 13505005 ( 0.078 sec)
2. f8e7 moves = 60529998 ( 0.266 sec)
2. f8d6 moves = 68409266 ( 0.234 sec)
2. f8c5 moves = 68305577 ( 0.266 sec)
2. f8b4 moves = 12613053 ( 0.078 sec)
2. f8a3 moves = 65315697 ( 0.234 sec)
2. h8g8 moves = 57085208 ( 0.078 sec)
2. e8e7 moves = 33572093 ( 0.063 sec)
perft( 6)= 1816240296 (11.438 sec)

--------------------------------------------------

Divided Perft(7) of Bb3 is wrong by only 2 nodes, but when doing Perft(6) of Bb3 the result is good (some hidden bug?). More complicated seems to me the other case (e6). I run perft of Critter 1.4 and Stockfish 2.2.2 (both of them in console mode) in the following position:

[d]rnbqkb1r/pp1p1ppp/2p1P3/8/2B5/8/PPP1NnPP/RNBQK2R b - 0 6

Code:

Critter v1.4 32-bit, by Richard Vida
position fen rnbqkb1r/pp1p1ppp/2p1P3/8/2B5/8/PPP1NnPP/RNBQK2R b KQkq - 0 6
perft 6
2461806026 nodes in 87000 ms, 28296 knps

Code:

Stockfish 2.2.2 JA by Tord Romstad, Marco Costalba and Joona Kiiski
position fen rnbqkb1r/pp1p1ppp/2p1P3/8/2B5/8/PPP1NnPP/RNBQK2R b KQkq - 0 6
perft 6

Nodes 2461806026
Time (ms) 59953
Nodes/second 41062265

I wonder the results of GNU 5.07.173b, NebiyuChess 1.42, etc. (too slow in my computer). I encourage other people to check this position with their own move generators, just for verification purposes.

Then, I tried dedicated perft programmes:

Code:

OliPerft -7 "rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 6"
r n b q k b . r
p p . p . p p p
. . p . . . . .
. . . . P . . .
. . B . . . . .
. . . . . . . .
P P P . N n P P
R N B Q K . . R

Ke1xf2: 1701268892
Ke1-f1: 2483161986
Ke1-d2: 1152858513
Pa2-a3: 2245837704
Pa2-a4: 2548648372
Pb2-b3: 2166557328
Pb2-b4: 2263311424
Pc2-c3: 2411002727
Pg2-g3: 1981011243
Pg2-g4: 2033046400
Ph2-h3: 2217212927
Ph2-h4: 2387827889
Pe5-e6: 2461806026
Nb1-d2: 1435627351
Nb1-a3: 2002068159
Nb1-c3: 2655487727
Ne2-g1: 2354927176
Ne2-c3: 3057530890
Ne2-g3: 2865273204
Ne2-d4: 3061284388
Ne2-f4: 2949871106
Rh1-f1: 2220729699
Rh1-g1: 1983977646
Ke1-g1: 2291266832
Bc1-d2: 2107363662
Bc1-e3: 3184524390
Bc1-f4: 2482656228
Bc1-g5: 2400385594
Bc1-h6: 2344263758
Bc4xf7: 86568355
Bc4-b3: 1816240296
Bc4-d3: 1886965922
Bc4-b5: 2130713616
Bc4-d5: 2046941872
Bc4-a6: 1855061374
Bc4-e6: 2444185312
Qd1xd7: 207937563
Qd1-d2: 2481769422
Qd1-d3: 3719739001
Qd1-d4: 3598056747
Qd1-d5: 2815305249
Qd1-d6: 2314600161

Nodes: 94854874131 cs: 126339 knps: 75079

Code:

frcperft-win32

frcperft 1.0, (C) 2008-2011 AJ Siemelink
single threaded, no hashing, mode=FAST, extract=BSF32, count=LOOP

+---+---+---+---+---+---+---+---+
8 |*r*|*n*|*b*|*q*|*k*|*b*|*n*|*r*|
+---+---+---+---+---+---+---+---+
7 |*p*|*p*|*p*|*p*|*p*|*p*|*p*|*p*|
+---+---+---+---+---+---+---+---+
6 | | | | | | | | |
+---+---+---+---+---+---+---+---+
5 | | | | | | | | |
+---+---+---+---+---+---+---+---+
4 | | | | | | | | |
+---+---+---+---+---+---+---+---+
3 | | | | | | | | |
+---+---+---+---+---+---+---+---+
2 |(P)|(P)|(P)|(P)|(P)|(P)|(P)|(P)|
+---+---+---+---+---+---+---+---+
1 |(R)|(N)|(B)|(Q)|(K)|(B)|(N)|(R)|
+---+---+---+---+---+---+---+---+
a b c d e f g h

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
interactive mode, type 'help'+Enter for help
% fen rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 6

+---+---+---+---+---+---+---+---+
8 |*r*|*n*|*b*|*q*|*k*|*b*| |*r*|
+---+---+---+---+---+---+---+---+
7 |*p*|*p*| |*p*| |*p*|*p*|*p*|
+---+---+---+---+---+---+---+---+
6 | | |*p*| | | | | |
+---+---+---+---+---+---+---+---+
5 | | | | |(P)| | | |
+---+---+---+---+---+---+---+---+
4 | | |(B)| | | | | |
+---+---+---+---+---+---+---+---+
3 | | | | | | | | |
+---+---+---+---+---+---+---+---+
2 |(P)|(P)|(P)| |(N)|*n*|(P)|(P)|
+---+---+---+---+---+---+---+---+
1 |(R)|(N)|(B)|(Q)|(K)| | |(R)|
+---+---+---+---+---+---+---+---+
a b c d e f g h

rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 1
% divide 7
O-O 2291266832
a4 2548648372
b4 2263311424
g4 2033046400
h4 2387827889
a3 2245837704
b3 2166557328
c3 2411002727
g3 1981011243
h3 2217212927
e6 2461806026
Nd2 1435627351
Na3 2002068159
Nbc3 2655487727
Ng1 2354927176
Nec3 3057530890
Ng3 2865273204
Nd4 3061284388
Nf4 2949871106
Bd2 2107363662
Be3 3184524390
Bf4 2482656228
Bg5 2400385594
Bh6 2344263758
Bb3 1816240296
Bd3 1886965922
Bb5 2130713616
Bd5 2046941872
Ba6 1855061374
Be6 2444185312
Bxf7 86568355
Qd2 2481769422
Qd3 3719739001
Qd4 3598056747
Qd5 2815305249
Qd6 2314600161
Qxd7 207937563
Rf1 2220729699
Rg1 1983977646
Kf1 2483161986
Kd2 1152858513
Kxf2 1701268892
-------------------
total 94854874131
% Around 72 minutes!

Code:

i-perft -divide 7 "rnbqkb1r/pp1p1ppp/2p5/4P3/2B5/8/PPP1NnPP/RNBQK2R w KQkq - 0 6"

i-perft 1.0 (c) 2006-2008 AJ Siemelink

+---+---+---+---+---+---+---+---+
8 |*r*|*n*|*b*|*q*|*k*|*b*| |*r*|
+---+---+---+---+---+---+---+---+
7 |*p*|*p*| |*p*| |*p*|*p*|*p*|
+---+---+---+---+---+---+---+---+
6 | | |*p*| | | | | |
+---+---+---+---+---+---+---+---+
5 | | | | |(P)| | | |
+---+---+---+---+---+---+---+---+
4 | | |(B)| | | | | |
+---+---+---+---+---+---+---+---+
3 | | | | | | | | |
+---+---+---+---+---+---+---+---+
2 |(P)|(P)|(P)| |(N)|*n*|(P)|(P)|
+---+---+---+---+---+---+---+---+
1 |(R)|(N)|(B)|(Q)|(K)| | |(R)|
+---+---+---+---+---+---+---+---+
a b c d e f g h

--divide--------------
Ke1g1 2291266832
e5e6 2325676972
a2a3 2123107962
a2a4 2413850557
b2b3 2046782855
b2b4 2141251457
c2c3 2279251420
g2g3 1868008811
g2g4 1917481468
h2h3 2098320010
h2h4 2269413040
Ne2g1 2345960033
Ne2c3 2902361581
Ne2g3 2725063064
Ne2d4 2907846050
Ne2f4 2806058340
Nb1d2 1349053003
Nb1a3 1890833545
Nb1c3 2513874218
Bc4b5 2013859334
Bc4a6 1752476016
Bc4d5 1933421928
Bc4e6 2307811200
Bc4xf7+ 81765044
Bc4d3 1780719048
Bc4b3 1711824192
Bc1d2 1979741418
Bc1e3 3020083840
Bc1f4 2353180659
Bc1g5 2279029333
Bc1h6 2220512706
Rh1g1 1983977087
Rh1f1 2220729140
Qd1d2 2339880427
Qd1d3 3536668777
Qd1d4 3418732701
Qd1d5 2670993689
Qd1d6 2202746795
Qd1xd7+ 193879619
Ke1f1 2483161986
Ke1xf2 1701268892
Ke1d2 1152858513
----------------------
total 90554783562 (1951.23 seconds)

Oliperft 1.01 and frcperft 1.0 agree with JetChess; I know that i-perft 1.0 is buggy (I only wanted to test its speed), but the following fact surprised me: it gives the exact numbers for O-O, Kf1, Kxf2 and Kd2, while gives 559 nodes less for Rg1 and other 559 nodes less for Rf1... the rest of the moves are counted very badly.

Summarizing: it looks like qperft is wrong and has some hidden bugs. It would be good that Muller or anyone else can confirm this issue (and fix it, in the case I am right).

For those who want to know where this position comes from, it is a kind of the Urusov/Ponziani Gambit:

1.- e4, e5; 2.- Bc4, Nf6; 3.- d4, c6; 4.- dxe5, Nxe4; 5.- Ne2, Nxf2 (the position of perft test, with the idea 6.- Kxf2?, Qh4+, forking the king and the light bishop, winning a pawn); 6.- O-O!? (tempting to the greedy 6.- ..., Nxd1?? (which leads to a mate in two); 7.- Bxf7+, Ke7 (the only move); 8.- Bg5#... a beautiful miniature).

Regards from Spain.

Ajedrecista.
_________________
Six Fortran 95 tools.

Chess will never be solved.

Display posts from previous:

Subject	Author	Date/Time
REPORT: wrong perft result by qperft.	Jesús Muñoz	Tue Feb 14, 2012 3:47 pm
Re: REPORT: wrong perft result by qperft.	Filip Tvrzsky	Tue Feb 14, 2012 6:29 pm
Re: REPORT: wrong perft result by qperft.	Michel Van den Bergh	Tue Feb 14, 2012 6:31 pm
Re: REPORT: wrong perft result by qperft.	kongsian	Wed Feb 15, 2012 12:03 am
Re: REPORT: wrong perft result by qperft.	Daniel Shawul	Wed Feb 15, 2012 4:36 am
Re: REPORT: wrong perft result by qperft.	Steven Edwards	Wed Feb 15, 2012 1:17 am
Re: REPORT: wrong perft result by qperft.	Heiner Marxen	Thu Feb 16, 2012 8:07 pm
Re: REPORT: wrong perft result by qperft.	Lucas Braesch	Sun Feb 19, 2012 7:51 am
Re: REPORT: wrong perft result by qperft.	Daniel Shawul	Wed Feb 15, 2012 1:46 am
Re: REPORT: wrong perft result by qperft.	Julien MARCEL	Wed Feb 15, 2012 10:03 am
Re: REPORT: wrong perft result by qperft.	Julien MARCEL	Wed Feb 15, 2012 7:30 pm
Re: REPORT: wrong perft result by qperft.	Jesús Muñoz	Thu Feb 16, 2012 11:47 am
Re: REPORT: wrong perft result by qperft.	H.G.Muller	Wed Feb 15, 2012 1:29 pm
To draft 8	Steven Edwards	Sun Feb 19, 2012 1:38 pm
Re: To draft 8	Paul Byrne	Sun Feb 19, 2012 8:17 pm
Re: To draft 8	Jesús Muñoz	Mon Feb 20, 2012 10:06 am
Re: To draft 8	Paul Byrne	Mon Feb 20, 2012 6:21 pm
Correction of my error.	Jesús Muñoz	Mon Feb 20, 2012 7:04 pm

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