Glaurung wrong mate scores

[Uri Blass]

It seems that glaurung's evaluation is too high in the following position and it see mate scores at small depth(when the depth is big enough it can see the draw)

New game - Rybka 2.3.2a 32-bit
[D]8/6kR/8/8/8/bq6/1rqqqqqq/K1nqnbrq b - - 0 1

Analysis by Glaurung 2-epsilon/4:

1...Qc2xh7
= (0.00) Depth: 2 00:00:00
1...Kg7-g8
# (#0) Depth: 2 00:00:00
1...Kg7-g8
# (#0) Depth: 3 00:00:00
1...Kg7-g8 2.Rh7-a7 Rb2-b1#
-+ (-#2) Depth: 4 00:00:00
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-a7 Rb2-b1#
-+ (-#4) Depth: 5 00:00:00
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-f7+ Kf8-e8 5.Rf7xf2 Rb2-b1#
-+ (-#5) Depth: 6 00:00:01 5kN
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-f7+ Kf8-e8 5.Rf7-e7+ Ke8-d8 6.Re7xe2 Nc1xe2#
-+ (-#6) Depth: 7 00:00:01 9kN
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-f8+ Kf7-e7 4.Rf8-e8+ Ke7-d7 5.Re8-d8+ Kd7-c7 6.Rd8-c8+ Kc7-b7 7.Rc8xc2 Ne1xc2#
-+ (-#7) Depth: 8 00:00:01 16kN
1...Kg7-g8 2.Rh7-g7+ Kg8-f8 3.Rg7-f7+ Kf8-e8 4.Rf7-e7+ Ke8-d8 5.Re7-d7+ Kd8-c8 6.Rd7-c7+ Kc8-b8 7.Rc7-b7+ Kb8-a8 8.Rb7-a7+ Ka8xa7
= (0.00) Depth: 9 00:00:01 40kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d7 5.Re6-e7+ Kd7-c6 6.Re7-c7+ Kc6-b6 7.Rc7-c6+ Kb6-a7 8.Rc6-a6+ Ka7-b8 9.Ra6xa3 Qb3xa3#
-+ (-#9) Depth: 9 00:00:01 99kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d7 5.Re6-e7+ Kd7-c6 6.Re7-c7+ Kc6-b6 7.Rc7-c6+ Kb6-a7 8.Rc6-a6+ Ka7-b8 9.Ra6-a8+ Kb8-c7 10.Ra8xa3 Qb3xa3#
-+ (-#10) Depth: 10 00:00:01 184kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-g4+ Kg5-f5 10.Rg4xg2 Rb2-b1#
-+ (-#10) Depth: 11 00:00:01 365kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g6 10.Re5-e6+ Kg6-g7 11.Re6xe2 Nc1xe2#
-+ (-#11) Depth: 12 00:00:01 540kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g6 10.Re5-e6+ Kg6-g7 11.Re6-e7+ Kg7-h6 12.Re7xe2 Rb2-b1#
-+ (-#12) Depth: 13 00:00:02 943kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g4 10.Re5-e4+ Kg4-h5 11.Re4-e5+ Kh5-h6 12.Re5-e6+ Kh6-h7 13.Re6-e7+ Kh7-h6
-+ (-#13) Depth: 14 00:00:02 1393kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g4 10.Re5-e4+ Kg4-h5 11.Re4-e5+ Kh5-h6 12.Re5-e6+ Kh6-h7 13.Re6-e7+ Qf2-f7 14.Re7xe2 Nc1xe2#
-+ (-#14) Depth: 15 00:00:03 2038kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-d4 7.Re6-e4+ Kd4-c5 8.Re4-c4+ Kc5-d5 9.Rc4-d4+ Kd5-e6 10.Rd4-e4+ Ke6-d7 11.Re4-e7+ Kd7-c6 12.Re7-c7+ Kc6-d5 13.Rc7-c5+ Kd5-e4 14.Rc5xc2 Ne1xc2#
-+ (-#14) Depth: 16 00:00:04 2448kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-d4 7.Re6-e4+ Kd4-c5 8.Re4-c4+ Kc5-d5 9.Rc4-d4+ Kd5-e6 10.Rd4-e4+ Ke6-d7 11.Re4-e7+ Kd7-c6 12.Re7-c7+ Kc6-d5 13.Rc7-c5+ Kd5-e4 14.Rc5xc2 Ne1xc2#
-+ (-#14) Depth: 17 00:00:04 2717kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 18 00:00:07 4455kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 19 00:00:08 5519kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 20 00:00:09 6503kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-d5 15.Re6-d6+ Kd5-c4 16.Rd6-d4+ Kc4-b5 17.Rd4-d5+
-+ (-#18) Depth: 21 00:00:12 8477kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 22 00:00:13 9240kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 23 00:00:14 10447kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 24 00:00:16 12265kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 25 00:00:19 14926kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c7 15.Re6-c6+ Kc7-d7 16.Rc6-d6+ Kd7-e8 17.Rd6-d8+
-+ (-#19) Depth: 26 00:00:28 22260kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c7 15.Re6-c6+ Kc7-d7 16.Rc6-d6+ Kd7-e8 17.Rd6-d8+
-+ (-#19) Depth: 27 00:00:36 29184kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d5 4.Re7-e5+ Kd5-d4 5.Re5-e4+ Kd4-c5 6.Re4-c4+ Kc5-d6 7.Rc4-c6+ Kd6-e5 8.Rc6-e6+ Ke5-f4 9.Re6-e4+ Kf4-g5 10.Re4-e5+ Kg5-h4 11.Re5-e4+ Kh4-h5 12.Re4-e5+ Qc2-f5 13.Re5xf5+ Kh5-g4 14.Rf5-f4+ Kg4-g5 15.Rf4-f5+ Kg5-h4 16.Rf5-f4+ Kh4-h5 17.Rf4-f5+
-+ (-#27) Depth: 28 00:00:57 46581kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d4 5.Re6-e4+ Kd4-c5 6.Re4-c4+ Kc5-d6 7.Rc4-c6+ Kd6-e5 8.Rc6-e6+ Ke5-d5 9.Re6-d6+ Kd5-e4 10.Rd6-d4+ Ke4-f5 11.Rd4-f4+ Kf5-e6 12.Rf4-e4+ Qh2-e5 13.Re4xe5+ Ke6-d6 14.Re5-d5+ Kd6-c7 15.Rd5-c5+ Kc7-d7 16.Rc5-c7+ Kd7-e6 17.Rc7-e7+
-+ (-#29) Depth: 29 00:01:14 61573kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 30 00:01:19 67158kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 31 00:01:26 74705kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 32 00:01:34 84977kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 33 00:01:48 98911kN

(, 23.06.2007)

[bob]

It seems that glaurung's evaluation is too high in the following position and it see mate scores at small depth(when the depth is big enough it can see the draw)

New game - Rybka 2.3.2a 32-bit
[D]8/6kR/8/8/8/bq6/1rqqqqqq/K1nqnbrq b - - 0 1

Analysis by Glaurung 2-epsilon/4:

1...Qc2xh7
= (0.00) Depth: 2 00:00:00
1...Kg7-g8
# (#0) Depth: 2 00:00:00
1...Kg7-g8
# (#0) Depth: 3 00:00:00
1...Kg7-g8 2.Rh7-a7 Rb2-b1#
-+ (-#2) Depth: 4 00:00:00
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-a7 Rb2-b1#
-+ (-#4) Depth: 5 00:00:00
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-f7+ Kf8-e8 5.Rf7xf2 Rb2-b1#
-+ (-#5) Depth: 6 00:00:01 5kN
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-f7+ Kf8-e8 5.Rf7-e7+ Ke8-d8 6.Re7xe2 Nc1xe2#
-+ (-#6) Depth: 7 00:00:01 9kN
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-f8+ Kf7-e7 4.Rf8-e8+ Ke7-d7 5.Re8-d8+ Kd7-c7 6.Rd8-c8+ Kc7-b7 7.Rc8xc2 Ne1xc2#
-+ (-#7) Depth: 8 00:00:01 16kN
1...Kg7-g8 2.Rh7-g7+ Kg8-f8 3.Rg7-f7+ Kf8-e8 4.Rf7-e7+ Ke8-d8 5.Re7-d7+ Kd8-c8 6.Rd7-c7+ Kc8-b8 7.Rc7-b7+ Kb8-a8 8.Rb7-a7+ Ka8xa7
= (0.00) Depth: 9 00:00:01 40kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d7 5.Re6-e7+ Kd7-c6 6.Re7-c7+ Kc6-b6 7.Rc7-c6+ Kb6-a7 8.Rc6-a6+ Ka7-b8 9.Ra6xa3 Qb3xa3#
-+ (-#9) Depth: 9 00:00:01 99kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d7 5.Re6-e7+ Kd7-c6 6.Re7-c7+ Kc6-b6 7.Rc7-c6+ Kb6-a7 8.Rc6-a6+ Ka7-b8 9.Ra6-a8+ Kb8-c7 10.Ra8xa3 Qb3xa3#
-+ (-#10) Depth: 10 00:00:01 184kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-g4+ Kg5-f5 10.Rg4xg2 Rb2-b1#
-+ (-#10) Depth: 11 00:00:01 365kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g6 10.Re5-e6+ Kg6-g7 11.Re6xe2 Nc1xe2#
-+ (-#11) Depth: 12 00:00:01 540kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g6 10.Re5-e6+ Kg6-g7 11.Re6-e7+ Kg7-h6 12.Re7xe2 Rb2-b1#
-+ (-#12) Depth: 13 00:00:02 943kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g4 10.Re5-e4+ Kg4-h5 11.Re4-e5+ Kh5-h6 12.Re5-e6+ Kh6-h7 13.Re6-e7+ Kh7-h6
-+ (-#13) Depth: 14 00:00:02 1393kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g4 10.Re5-e4+ Kg4-h5 11.Re4-e5+ Kh5-h6 12.Re5-e6+ Kh6-h7 13.Re6-e7+ Qf2-f7 14.Re7xe2 Nc1xe2#
-+ (-#14) Depth: 15 00:00:03 2038kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-d4 7.Re6-e4+ Kd4-c5 8.Re4-c4+ Kc5-d5 9.Rc4-d4+ Kd5-e6 10.Rd4-e4+ Ke6-d7 11.Re4-e7+ Kd7-c6 12.Re7-c7+ Kc6-d5 13.Rc7-c5+ Kd5-e4 14.Rc5xc2 Ne1xc2#
-+ (-#14) Depth: 16 00:00:04 2448kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-d4 7.Re6-e4+ Kd4-c5 8.Re4-c4+ Kc5-d5 9.Rc4-d4+ Kd5-e6 10.Rd4-e4+ Ke6-d7 11.Re4-e7+ Kd7-c6 12.Re7-c7+ Kc6-d5 13.Rc7-c5+ Kd5-e4 14.Rc5xc2 Ne1xc2#
-+ (-#14) Depth: 17 00:00:04 2717kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 18 00:00:07 4455kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 19 00:00:08 5519kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 20 00:00:09 6503kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-d5 15.Re6-d6+ Kd5-c4 16.Rd6-d4+ Kc4-b5 17.Rd4-d5+
-+ (-#18) Depth: 21 00:00:12 8477kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 22 00:00:13 9240kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 23 00:00:14 10447kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 24 00:00:16 12265kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 25 00:00:19 14926kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c7 15.Re6-c6+ Kc7-d7 16.Rc6-d6+ Kd7-e8 17.Rd6-d8+
-+ (-#19) Depth: 26 00:00:28 22260kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c7 15.Re6-c6+ Kc7-d7 16.Rc6-d6+ Kd7-e8 17.Rd6-d8+
-+ (-#19) Depth: 27 00:00:36 29184kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d5 4.Re7-e5+ Kd5-d4 5.Re5-e4+ Kd4-c5 6.Re4-c4+ Kc5-d6 7.Rc4-c6+ Kd6-e5 8.Rc6-e6+ Ke5-f4 9.Re6-e4+ Kf4-g5 10.Re4-e5+ Kg5-h4 11.Re5-e4+ Kh4-h5 12.Re4-e5+ Qc2-f5 13.Re5xf5+ Kh5-g4 14.Rf5-f4+ Kg4-g5 15.Rf4-f5+ Kg5-h4 16.Rf5-f4+ Kh4-h5 17.Rf4-f5+
-+ (-#27) Depth: 28 00:00:57 46581kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d4 5.Re6-e4+ Kd4-c5 6.Re4-c4+ Kc5-d6 7.Rc4-c6+ Kd6-e5 8.Rc6-e6+ Ke5-d5 9.Re6-d6+ Kd5-e4 10.Rd6-d4+ Ke4-f5 11.Rd4-f4+ Kf5-e6 12.Rf4-e4+ Qh2-e5 13.Re4xe5+ Ke6-d6 14.Re5-d5+ Kd6-c7 15.Rd5-c5+ Kc7-d7 16.Rc5-c7+ Kd7-e6 17.Rc7-e7+
-+ (-#29) Depth: 29 00:01:14 61573kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 30 00:01:19 67158kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 31 00:01:26 74705kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 32 00:01:34 84977kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 33 00:01:48 98911kN

(, 23.06.2007)

programs have many sorts of bugs. In my cluster testing, Arasan (as but one example) has problems resigning and tries to resign but give the wrong result (it plays white, and sends "1-0 Black resigns" in some cases, I had to make my referee program handle that nonsense correctly.

[Tord Romstad]

It seems that glaurung's evaluation is too high in the following position and it see mate scores at small depth(when the depth is big enough it can see the draw)

Hello Uri,

Thanks for reporting this! I haven't looked at my code, but I am fairly sure I understand what is happening here: Black is so far ahead in material that the static evaluation function returns a score that is better than a mate score. The program therefore thinks it is better for white to accept being mated rather than accepting a static evaluation which is even worse (from white's point of view).

The bug should be easy to fix, of course: Just crop that the static evaluation score so that the absolute value is never bigger than a mate score.

Fortunately, this bug isn't likely to have a big impact on practical playing strength.

Tord

[glorfindel]

The bug should be easy to fix, of course: Just crop that the static evaluation score so that the absolute value is never bigger than a mate score.

Is that why many engines are reporting a score of +327.66 when they see a mate? I always wondered what is the significance of this number.

[Tord Romstad]

Is that why many engines are reporting a score of +327.66 when they see a mate? I always wondered what is the significance of this number.

You are probably right. If an engine uses signed 16-bit integers to represent scores (which is probably a common choice), the possible range of scores is from -32768 to +32767 (the number 32768 is equal to 2 to the power of 15). It is therefore natural to use 32767 (or something similar) to represent the best possible score, i.e. a mate. If the value of a pawn is represented by the number 100, a mate score will be printed as something close to +327.66.

In Glaurung, it looks a bit different: The value of mate is +30000, and the value of a pawn is 256. When the scores are printed to the standard output, they are converted to the scale pawn = 1.00, and mate scores are displayed as "mate in n" rather than as a numerical score.

Tord

[geots]

It seems that glaurung's evaluation is too high in the following position and it see mate scores at small depth(when the depth is big enough it can see the draw)

New game - Rybka 2.3.2a 32-bit
[D]8/6kR/8/8/8/bq6/1rqqqqqq/K1nqnbrq b - - 0 1

Analysis by Glaurung 2-epsilon/4:

1...Qc2xh7
= (0.00) Depth: 2 00:00:00
1...Kg7-g8
# (#0) Depth: 2 00:00:00
1...Kg7-g8
# (#0) Depth: 3 00:00:00
1...Kg7-g8 2.Rh7-a7 Rb2-b1#
-+ (-#2) Depth: 4 00:00:00
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-a7 Rb2-b1#
-+ (-#4) Depth: 5 00:00:00
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-f7+ Kf8-e8 5.Rf7xf2 Rb2-b1#
-+ (-#5) Depth: 6 00:00:01 5kN
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-h7+ Kf7-f8 4.Rh7-f7+ Kf8-e8 5.Rf7-e7+ Ke8-d8 6.Re7xe2 Nc1xe2#
-+ (-#6) Depth: 7 00:00:01 9kN
1...Kg7-g8 2.Rh7-h8+ Kg8-f7 3.Rh8-f8+ Kf7-e7 4.Rf8-e8+ Ke7-d7 5.Re8-d8+ Kd7-c7 6.Rd8-c8+ Kc7-b7 7.Rc8xc2 Ne1xc2#
-+ (-#7) Depth: 8 00:00:01 16kN
1...Kg7-g8 2.Rh7-g7+ Kg8-f8 3.Rg7-f7+ Kf8-e8 4.Rf7-e7+ Ke8-d8 5.Re7-d7+ Kd8-c8 6.Rd7-c7+ Kc8-b8 7.Rc7-b7+ Kb8-a8 8.Rb7-a7+ Ka8xa7
= (0.00) Depth: 9 00:00:01 40kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d7 5.Re6-e7+ Kd7-c6 6.Re7-c7+ Kc6-b6 7.Rc7-c6+ Kb6-a7 8.Rc6-a6+ Ka7-b8 9.Ra6xa3 Qb3xa3#
-+ (-#9) Depth: 9 00:00:01 99kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d7 5.Re6-e7+ Kd7-c6 6.Re7-c7+ Kc6-b6 7.Rc7-c6+ Kb6-a7 8.Rc6-a6+ Ka7-b8 9.Ra6-a8+ Kb8-c7 10.Ra8xa3 Qb3xa3#
-+ (-#10) Depth: 10 00:00:01 184kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-g4+ Kg5-f5 10.Rg4xg2 Rb2-b1#
-+ (-#10) Depth: 11 00:00:01 365kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g6 10.Re5-e6+ Kg6-g7 11.Re6xe2 Nc1xe2#
-+ (-#11) Depth: 12 00:00:01 540kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g6 10.Re5-e6+ Kg6-g7 11.Re6-e7+ Kg7-h6 12.Re7xe2 Rb2-b1#
-+ (-#12) Depth: 13 00:00:02 943kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g4 10.Re5-e4+ Kg4-h5 11.Re4-e5+ Kh5-h6 12.Re5-e6+ Kh6-h7 13.Re6-e7+ Kh7-h6
-+ (-#13) Depth: 14 00:00:02 1393kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-f3 7.Re6-e3+ Kf3-f4 8.Re3-e4+ Kf4-g5 9.Re4-e5+ Kg5-g4 10.Re5-e4+ Kg4-h5 11.Re4-e5+ Kh5-h6 12.Re5-e6+ Kh6-h7 13.Re6-e7+ Qf2-f7 14.Re7xe2 Nc1xe2#
-+ (-#14) Depth: 15 00:00:03 2038kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-d4 7.Re6-e4+ Kd4-c5 8.Re4-c4+ Kc5-d5 9.Rc4-d4+ Kd5-e6 10.Rd4-e4+ Ke6-d7 11.Re4-e7+ Kd7-c6 12.Re7-c7+ Kc6-d5 13.Rc7-c5+ Kd5-e4 14.Rc5xc2 Ne1xc2#
-+ (-#14) Depth: 16 00:00:04 2448kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-d6+ Kd5-e4 6.Rd6-e6+ Ke4-d4 7.Re6-e4+ Kd4-c5 8.Re4-c4+ Kc5-d5 9.Rc4-d4+ Kd5-e6 10.Rd4-e4+ Ke6-d7 11.Re4-e7+ Kd7-c6 12.Re7-c7+ Kc6-d5 13.Rc7-c5+ Kd5-e4 14.Rc5xc2 Ne1xc2#
-+ (-#14) Depth: 17 00:00:04 2717kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 18 00:00:07 4455kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 19 00:00:08 5519kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d5 8.Rc4-c5+ Kd5-e4 9.Rc5-e5+ Ke4-d3 10.Re5-e3+ Kd3-c4 11.Re3-c3+ Kc4-d4 12.Rc3-c4+ Kd4-e5 13.Rc4-e4+ Ke5-f5 14.Re4-e5+ Kf5-g4 15.Re5-e4+ Kg4-g5 16.Re4-e5+ Kg5-h6 17.Re5xe2
-+ (-#17) Depth: 20 00:00:09 6503kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-d5 15.Re6-d6+ Kd5-c4 16.Rd6-d4+ Kc4-b5 17.Rd4-d5+
-+ (-#18) Depth: 21 00:00:12 8477kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 22 00:00:13 9240kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 23 00:00:14 10447kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 24 00:00:16 12265kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c5 15.Re6-c6+ Kc5-d4 16.Rc6-c4+ Kd4-e5 17.Rc4-e4+
-+ (-#18) Depth: 25 00:00:19 14926kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c7 15.Re6-c6+ Kc7-d7 16.Rc6-d6+ Kd7-e8 17.Rd6-d8+
-+ (-#19) Depth: 26 00:00:28 22260kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d6 4.Re7-e6+ Kd6-d5 5.Re6-e5+ Kd5-d4 6.Re5-e4+ Kd4-c5 7.Re4-c4+ Kc5-d6 8.Rc4-d4+ Qg2-d5 9.Rd4xd5+ Kd6-e7 10.Rd5-e5+ Ke7-f7 11.Re5-f5+ Kf7-e8 12.Rf5-e5+ Ke8-d7 13.Re5-e7+ Kd7-d6 14.Re7-e6+ Kd6-c7 15.Re6-c6+ Kc7-d7 16.Rc6-d6+ Kd7-e8 17.Rd6-d8+
-+ (-#19) Depth: 27 00:00:36 29184kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e6 3.Rf7-e7+ Ke6-d5 4.Re7-e5+ Kd5-d4 5.Re5-e4+ Kd4-c5 6.Re4-c4+ Kc5-d6 7.Rc4-c6+ Kd6-e5 8.Rc6-e6+ Ke5-f4 9.Re6-e4+ Kf4-g5 10.Re4-e5+ Kg5-h4 11.Re5-e4+ Kh4-h5 12.Re4-e5+ Qc2-f5 13.Re5xf5+ Kh5-g4 14.Rf5-f4+ Kg4-g5 15.Rf4-f5+ Kg5-h4 16.Rf5-f4+ Kh4-h5 17.Rf4-f5+
-+ (-#27) Depth: 28 00:00:57 46581kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d4 5.Re6-e4+ Kd4-c5 6.Re4-c4+ Kc5-d6 7.Rc4-c6+ Kd6-e5 8.Rc6-e6+ Ke5-d5 9.Re6-d6+ Kd5-e4 10.Rd6-d4+ Ke4-f5 11.Rd4-f4+ Kf5-e6 12.Rf4-e4+ Qh2-e5 13.Re4xe5+ Ke6-d6 14.Re5-d5+ Kd6-c7 15.Rd5-c5+ Kc7-d7 16.Rc5-c7+ Kd7-e6 17.Rc7-e7+
-+ (-#29) Depth: 29 00:01:14 61573kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 30 00:01:19 67158kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 31 00:01:26 74705kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 32 00:01:34 84977kN
1...Kg7-f6 2.Rh7-f7+ Kf6-e5 3.Rf7-e7+ Qb3-e6 4.Re7xe6+ Ke5-d5 5.Re6-d6+ Kd5-e4 6.Rd6-d4+ Ke4-f5 7.Rd4-f4+ Kf5-e6 8.Rf4-f6+ Ke6-e5 9.Rf6-e6+ Ke5-d5
= (0.00) Depth: 33 00:01:48 98911kN

(, 23.06.2007)

No offense meant here, Uri. But if you are going to show me a bug found in a program, please show me where you found it in a position that actually came up or could easily come up in game play. All these weird positions that are impossible to reproduce in game play are just a waste of time and bandwidth IMHO.

Best regards,

[Alessandro Scotti]

No offense meant here, Uri. But if you are going to show me a bug found in a program, please show me where you found it in a position that actually came up or could easily come up in game play. All these weird positions that are impossible to reproduce in game play are just a waste of time and bandwidth IMHO.

Well a bug is always a bug... Personally, I am interested in any kind of bug reports as several of those have helped find bugs in my own engines in the past. Because of this, I tend to welcome posts like Uri's.

[geots]

No offense meant here, Uri. But if you are going to show me a bug found in a program, please show me where you found it in a position that actually came up or could easily come up in game play. All these weird positions that are impossible to reproduce in game play are just a waste of time and bandwidth IMHO.

Well a bug is always a bug... Personally, I am interested in any kind of bug reports as several of those have helped find bugs in my own engines in the past. Because of this, I tend to welcome posts like Uri's.

I probably have to agree, when realizing posts like Uri's are meant more for programmers as yourself rather than people like me who have no concept of programming issues. Another case of my speaking too soon w/o thinking it thru.

Regards,

[Tord Romstad]

No offense meant here, Uri. But if you are going to show me a bug found in a program, please show me where you found it in a position that actually came up or could easily come up in game play. All these weird positions that are impossible to reproduce in game play are just a waste of time and bandwidth IMHO.

Not necessarily: Sometimes it could happen that the bugs you see in such extremely artificial positions can have a negative effect in some normal chess positions, too, but be much more difficult to spot there. In this particular case, the bug has zero importance for practical game play (the bug can only occur when one side has a material advantage worth more than 100 pawns), but in other cases it could be different.

Tord

[Dann Corbit]

Is that why many engines are reporting a score of +327.66 when they see a mate? I always wondered what is the significance of this number.

You are probably right. If an engine uses signed 16-bit integers to represent scores (which is probably a common choice), the possible range of scores is from -32768 to +32767 (the number 32768 is equal to 2 to the power of 15). It is therefore natural to use 32767 (or something similar) to represent the best possible score, i.e. a mate. If the value of a pawn is represented by the number 100, a mate score will be printed as something close to +327.66.

In Glaurung, it looks a bit different: The value of mate is +30000, and the value of a pawn is 256. When the scores are printed to the standard output, they are converted to the scale pawn = 1.00, and mate scores are displayed as "mate in n" rather than as a numerical score.

Tord

The frequently seen 32766 is directly from the PGN standard:

"16.2.5.6: Opcode "ce": centipawn evaluation

The opcode "ce" indicates the evaluation of the indicated position in centipawn
units. It takes a single operand, an optionally signed integer that gives an
evaluation of the position from the viewpoint of the active player; i.e., the
player with the move. Positive values indicate a position favorable to the
moving player while negative values indicate a position favorable to the
passive player; i.e., the player without the move. A centipawn evaluation
value close to zero indicates a neutral positional evaluation.

Values are restricted to integers that are equal to or greater than -32767 and
are less than or equal to 32766.

A value greater than 32000 indicates the availability of a forced mate to the
active player. The number of plies until mate is given by subtracting the
evaluation from the value 32767. Thus, a winning mate in N fullmoves is a mate
in ((2 * N) - 1) halfmoves (or ply) and has a corresponding centipawn
evaluation of (32767 - ((2 * N) - 1)). For example, a mate on the move (mate
in one) has a centipawn evaluation of 32766 while a mate in five has a
centipawn evaluation of 32758.

A value less than -32000 indicates the availability of a forced mate to the
passive player. The number of plies until mate is given by subtracting the
evaluation from the value -32767 and then negating the result. Thus, a losing
mate in N fullmoves is a mate in (2 * N) halfmoves (or ply) and has a
corresponding centipawn evaluation of (-32767 + (2 * N)). For example, a mate
after the move (losing mate in one) has a centipawn evaluation of -32765 while
a losing mate in five has a centipawn evaluation of -32757.

A value of -32767 indicates an illegal position. A stalemate position has a
centipawn evaluation of zero as does a position drawn due to insufficient
mating material. Any other position known to be a certain forced draw also has
a centipawn evaluation of zero."