Colossus 2025b now available

[MartinBryant]

I have just released an updated version of my Colossus engine on my website at http://www.colossusgames.co.uk

Changes include late-move pruning, null-move refinements, a small evaluation mod and various tweaks.
My tests indicate an improvement of about 25 ELO.

[mclane]

Thank you Martin. Perfect update „service“.

[skalde]

Hi Martin, thank you for the update! By the way, for me, Colossus2025b seems buggy and make the gui freezes... both on fritz gui and cutechess

[Programmingbear]

Hi,

Hi Martin, thank you for the update! By the way, for me, Colossus2025b seems buggy and make the gui freezes... both on fritz gui and cutechess

do you have more information when this happens? I have not yet been able to reproduce this under BearChess.
By the way, an error in an engine should not cause the GUI to freeze
Lars

[MartinBryant]

Sorry to hear that.
I used to use cutechess-cli for test runs but have changed to fastchess under which I have run tens of thousands of test games without problem. Also it's currently running ok as a lichess bot and I also run it in my own personal GUI and ran a test tourney in Arena before releasing it.
I did change the messaging output to be 'quieter' than it used to be. So it may not display any messages for the first couple of seconds.
Is that what you mean by 'freezes'? Or does it kill the GUI entirely?

[Steve Maughan]

I can confirm Colossus 2025b crashes quite a lot in the Shredder GUI when analyzing different position. I suspect it's to do with the 'position fen' command. This sort of bug wouldn't show up in games against engines. I exported a "ucilog.txt" files and found the problem.

If you start Colossus 2025b as a console app, and type the following:

Code: Select all

uci
position fen 1rq5/p3kp2/2Bp1p2/1P2p1r1/QP3n2/2P5/5PPP/R4RK1 b - - moves

It will crash. I believe the problem is Colossus is expecting some moves after the 'move' keyword. It should be a simple fix.

— Steve

[MartinBryant]

I can confirm Colossus 2025b crashes quite a lot in the Shredder GUI when analyzing different position. I suspect it's to do with the 'position fen' command. This sort of bug wouldn't show up in games against engines. I exported a "ucilog.txt" files and found the problem.

If you start Colossus 2025b as a console app, and type the following:

Code: Select all

uci
position fen 1rq5/p3kp2/2Bp1p2/1P2p1r1/QP3n2/2P5/5PPP/R4RK1 b - - moves

It will crash. I believe the problem is Colossus is expecting some moves after the 'move' keyword. It should be a simple fix.

— Steve

Thanks Steve. It does indeed. I'll fix it for the next version.
How bizarre though that some GUIs would suffix 'moves' when there aren't any. The joys of a very loose UCI 'standard'.

[Programmingbear]

I can confirm Colossus 2025b crashes quite a lot in the Shredder GUI when analyzing different position. I suspect it's to do with the 'position fen' command. This sort of bug wouldn't show up in games against engines. I exported a "ucilog.txt" files and found the problem.

If you start Colossus 2025b as a console app, and type the following:

Code: Select all

uci
position fen 1rq5/p3kp2/2Bp1p2/1P2p1r1/QP3n2/2P5/5PPP/R4RK1 b - - moves

It will crash. I believe the problem is Colossus is expecting some moves after the 'move' keyword. It should be a simple fix.

— Steve

Thanks Steve. It does indeed. I'll fix it for the next version.
How bizarre though that some GUIs would suffix 'moves' when there aren't any. The joys of a very loose UCI 'standard'.

Unfortunately, the UCI definition could be understood to mean that “moves” should always come:

Code: Select all

 position [fen <fenstring> | startpos ]  moves <move1> .... <movei>
 

Of course, this only makes sense if moves have actually been made.
In BearChess I had chosen the logical version

Lars

[chessica]

[d]1B3B1B/2B5/p6B/8/8/8/8/1k1K4 w - - 0 1

Colossus 2025b:

18 00:00,709 1.769k 2.495k +17,69 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lb8-a7 a4-a3 Lb2xa3 Kb1-a2 Kd1-c2 Ka2-a1 Lc1-h6 Ka1-a2 La3-d6 Ka2-a1 La7-d4+ Ka1-a2 Ld4-e3 Ka2-a1 Lf8-e7 Ka1-a2 Ld6-b4 Ka2-a1 Le7-c5 Ka1-a2 Lc5-b6 Ka2-a1 Lc7-f4 Ka1-a2 Lh6-f8 Ka2-a1
19 00:01,248 2.984k 2.391k +17,69 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lb8-a7 a4-a3 Lb2xa3 Kb1-a2 Kd1-c2 Ka2-a1 Lc1-h6 Ka1-a2 La3-d6 Ka2-a1 La7-d4+ Ka1-a2 Ld4-e3 Ka2-a1 Lf8-e7 Ka1-a2 Ld6-b4 Ka2-a1 Le7-c5 Ka1-a2 Lc5-b6 Ka2-a1 Lc7-f4 Ka1-a2 Lb6-c5 Ka2-a1 Lf4-b8 Ka1-a2
20 00:02,504 5.794k 2.314k +17,71 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lb8-a7 a4-a3 Lb2xa3 Kb1-a2 Kd1-c2 Ka2-a1 Lc1-h6 Ka1-a2 La3-d6 Ka2-a1 La7-d4+ Ka1-a2 Ld4-e3 Ka2-a1 Lf8-e7 Ka1-a2 Ld6-g3 Ka2-a1 Le3-d4+ Ka1-a2 Ld4-f2 Ka2-a1 Lg3-e5+ Ka1-a2 Le5-d6 Ka2-a1 Lf2-d4+ Ka1-a2 Ld4-e3 Ka2-a1 Ld6-b4 Ka1-a2 Le7-c5 Ka2-a1 Lc7-e5+ Ka1-a2 Kc2-c3
21 00:04,434 10.066k 2.270k +17,71 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lc7-h2 a4-a3 Lb2xa3 Kb1-a2 Kd1-c2 Ka2-a1 Lf8-e7 Ka1-a2 Le7-c5 Ka2-a1 Lc5-g1 Ka1-a2 Lb8-a7 Ka2-a1 La3-b4 Ka1-a2 Lg1-c5 Ka2-a1 Lc1-g5 Ka1-a2 Lc5-e3 Ka2-a1 Lh2-e5+ Ka1-a2 Le5-c7 Ka2-a1 La7-c5 Ka1-a2 Lg5-h6 Ka2-a1 Lc7-e5+ Ka1-a2 Le5-d6 Ka2-a1
22/43 00:07,470 16.586k 2.220k +17,71 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lc7-h2 a4-a3 Lb2xa3 Kb1-a2 Kd1-c2 Ka2-a1 Lf8-e7 Ka1-a2 Le7-c5 Ka2-a1 Lc5-g1 Ka1-a2 Lb8-a7 Ka2-a1 La3-b4 Ka1-a2 Lg1-c5 Ka2-a1 Lc1-g5 Ka1-a2 Lc5-e3 Ka2-a1 Lh2-e5+ Ka1-a2 Le5-c7 Ka2-a1 La7-c5 Ka1-a2 Lg5-h6 Ka2-a1 Lc7-e5+ Ka1-a2 Le5-d6 Ka2-a1 Ld6-b8 Ka1-a2
23/43 00:17,031 37.414k 2.197k +17,69 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lc7-h2 a4-a3 Lb2xa3 Kb1-a2 Kd1-c2 Ka2-a1 Lf8-e7 Ka1-a2 Le7-c5 Ka2-a1 Lc5-g1 Ka1-a2 Lb8-a7 Ka2-a1 La3-b4 Ka1-a2 Lg1-c5 Ka2-a1 Lb4-a3 Ka1-a2 Lc1-h6 Ka2-a1 Kc2-b3 Ka1-b1 La7-b8 Kb1-a1 Lh2-e5+ Ka1-b1 Le5-f4 Kb1-a1 Lc5-f8 Ka1-b1 La3-c5 Kb1-a1 Lb8-e5+ Ka1-b1 Le5-d6 Kb1-a1
23/43 00:28,570 62.486k 2.187k +17,70 Kd1-d2 a6-a5 Lc7xa5 Kb1-a2 Kd2-c3 Ka2-b1 Lh6-e3 Kb1-a2 Kc3-c4 Ka2-b1 Kc4-d3 Kb1-a2 Kd3-c3 Ka2-b1 Lh8-e5 Kb1-a2 Le5-h2 Ka2-b1 Kc3-b3 Kb1-a1 Lf8-g7+ Ka1-b1 Lg7-h6 Kb1-a1 Lh6-f8 Ka1-b1 Lf8-e7 Kb1-a1 Lh2-e5+ Ka1-b1 Kb3-c3 Kb1-a2 Le7-f8 Ka2-b1
24/47 00:40,768 88.909k 2.181k +17,70 Kd1-d2 a6-a5 Lc7xa5 Kb1-a2 Kd2-c3 Ka2-b1 Lh6-e3 Kb1-a2 Kc3-c4 Ka2-b1 Kc4-d3 Kb1-a2 Kd3-c3 Ka2-b1 Lh8-e5 Kb1-a2 Le5-h2 Ka2-b1 Kc3-b3 Kb1-a1 Lf8-g7+ Ka1-b1 Lg7-h6 Kb1-a1 Lh6-f8 Ka1-b1 Lf8-e7 Kb1-a1 Lh2-e5+ Ka1-b1 Kb3-c3 Kb1-a2 Le7-f8 Ka2-b1 Le5-h2 Kb1-a2
24/47 00:51,190 111.392k 2.176k +17,75 Lh6-c1 a6-a5 Lh8-b2 a5-a4 Lc7-h2 a4-a3 Lb2xa3 Kb1-a1 Kd1-c2 Ka1-a2 Lf8-e7 Ka2-a1 La3-b2+ Ka1-a2 Kc2-c3 Ka2-b1 Le7-c5 Kb1-a2 Lc1-e3 Ka2-b1 Lb8-e5 Kb1-a2 Kc3-c4 Ka2-b1 Kc4-d3 Kb1-a2 Kd3-c3 Ka2-b1 Le3-h6 Kb1-a2 Le5-b8 Ka2-b1 Lb2-a3 Kb1-a2 Kc3-c2 Ka2-a1 Kc2-b3 Ka1-b1 Lc5-f8 Kb1-a1
25/51 01:34,976 204.145k 2.149k +17,78 Lh6-c1 a6-a5 Lb8-a7 a5-a4 Lf8-a3 Kb1-a2 Kd1-d2 Ka2-b3 Kd2-d3 Kb3-a2 La7-c5 Ka2-b3 Lc1-h6 Kb3-a2 Lc5-f8 Ka2-b1 Lh8-f6 Kb1-a2 Lc7-b8 Ka2-b1 Lf6-h8 Kb1-a2 Lh8-e5 Ka2-b3 Le5-d6 Kb3-a2 Kd3-c2 Ka2-a1 Ld6-e5+ Ka1-a2 La3-c5 a4-a3 Le5-c7 Ka2-a1 Lc5-d4+ Ka1-a2
26/51 02:56,346 370.040k 2.098k +17,78 Lh6-c1 a6-a5 Lb8-a7 a5-a4 Lf8-a3 Kb1-a2 Kd1-d2 Ka2-b3 Kd2-d3 Kb3-a2 La7-c5 Ka2-b3 Lc1-h6 Kb3-a2 Lc5-f8 Ka2-b1 Lc7-b8 Kb1-a2 Lh8-e5 Ka2-b1 Le5-f4 Kb1-a2 Kd3-c2 Ka2-a1 Lf4-e5+ Ka1-a2 Le5-g3 Ka2-a1 Lg3-f4 Ka1-a2 Lf8-b4 Ka2-a1 Lb4-c5 Ka1-a2 Lf4-d6 Ka2-a1 La3-b2+ Ka1-a2 Lc5-b6 a4-a3
27/51 05:46,376 707.025k 2.041k +17,78 Lh6-c1 a6-a5 Lb8-a7 a5-a4 Lf8-a3 Kb1-a2 Kd1-d2 Ka2-b3 Kd2-d3 Kb3-a2 La7-c5 Ka2-b3 Lc1-h6 Kb3-a2 Lc5-f8 Ka2-b1 Lc7-b8 Kb1-a2 Lh6-f4 Ka2-b3 Lf4-e5 Kb3-a2 Le5-g3 Ka2-b1 Lg3-f4 Kb1-a2 Lf4-d6 Ka2-b1 Ld6-c7 Kb1-a2 Lc7-e5 Ka2-b1 Kd3-e2 Kb1-a2
28/51 10:46,473 1.304.725k 2.018k +17,78 Lh6-c1 a6-a5 Lb8-a7 a5-a4 Lf8-a3 Kb1-a2 Kd1-d2 Ka2-b3 Kd2-d3 Kb3-a2 Kd3-c4 Ka2-b1 Kc4-c3 Kb1-a2 Lh8-d4 Ka2-b1 Lc7-e5 Kb1-a2 Kc3-d3 Ka2-b1 Ld4-b2 Kb1-a2 Le5-f4 Ka2-b1 La3-e7 Kb1-a2 Kd3-c2 a4-a3 Lb2xa3 Ka2-a1 Lc1-e3 Ka1-a2 Le7-c5 Ka2-a1 Lc5-d6 Ka1-a2 La7-b8 Ka2-a1
29/51 29:44,995 3.570.699k 2.000k +17,78 Lh6-c1 a6-a5 Lb8-a7 a5-a4 Lf8-a3 Kb1-a2 Kd1-d2 Ka2-b3 Kd2-d3 Kb3-a2 Kd3-c4 Ka2-b1 Kc4-c3 Kb1-a2 Lh8-d4 Ka2-b1 Lc7-e5 Kb1-a2 Kc3-d3 Ka2-b1 La7-b8 Kb1-a2 Ld4-c5 Ka2-b1 Le5-g3 Kb1-a2 Kd3-c2 Ka2-a1 La3-b2+ Ka1-a2 Lb8-c7 a4-a3 Lb2xa3 Ka2-a1 Lc1-h6 Ka1-a2 Lc7-b8 Ka2-a1 Lg3-e5+ Ka1-a2 Le5-d6 Ka2-a1 Lc5-d4+ Ka1-a2 Ld4-f2 Ka2-a1
29/51+ 30:12,977 3.624.052k 1.999k +M11 Lc7-e5
29/51 35:56,998 4.356.030k 2.019k +M9 Lc7-e5 a6-a5 Le5-a1 a5-a4 Lb8-e5 a4-a3 Kd1-d2 Kb1-a2 Kd2-c3 Ka2xa1 Kc3-b3+ Ka1-b1 Le5-a1 a3-a2 Kb3-c3 Kb1xa1 Kc3-c2+
30/55 40:31,250 4.971.845k 2.045k +M9 Lc7-e5 a6-a5 Le5-a1 a5-a4 Lb8-e5 a4-a3 Kd1-d2 Kb1-a2 Kd2-c3 Ka2xa1 Kc3-b3+ Ka1-b1 Le5-a1 a3-a2 Kb3-c3 Kb1xa1 Kc3-c2+
31/55 50:32,139 6.376.446k 2.103k +M9 Lc7-e5 a6-a5 Le5-a1 a5-a4 Lb8-e5 a4-a3 Kd1-d2 Kb1-a2 Kd2-c3 Ka2xa1 Kc3-b3+ Ka1-b1 Le5-a1 a3-a2 Kb3-c3 Kb1xa1 Kc3-c2+
32/61 56:49,229 7.765.457k 2.278k +M9 Lc7-e5 a6-a5 Le5-a1 a5-a4 Lb8-e5 a4-a3 Kd1-d2 Kb1-a2 Kd2-c3 Ka2xa1 Kc3-b3+ Ka1-b1 Le5-a1 a3-a2 Kb3-c3 Kb1xa1 Kc3-c2+

[MartinBryant]

Nice problem! I've not seen it before so I've added it to my collection, thank you.

It reminds me of this old chestnut...
[d]k2b3b/8/2N2b2/6b1/1b6/b7/3b2K1/b1b2B1n w - - 0 1
...which is a mate in 10

Can I ask what settings you used? Hash? Threads? And what processor did you use?