Tenax ver. 0.7.8 released

[carotino]

Tenax (a Latin term meaning tenacious) is a UCI compatible chess engine written in ANSI C.
Tenax is a traditional Alpha/Beta engine (not NNUE) and uses the most modern move search and selection techniques.

Tenax support Szigigy Table Bases.
Tenax has a playing strength of around 3000, 3100 ELO points (rough estimate).

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SEARCHING & EXTENSIONS
--------------------
Iterative Deepening
Negamax
Quiescence
Aspiration Windows
Transposition Table
Futility Pruning
Razoring
Null Move Pruning
Prob Cut
LMR / LMP
Internal Iterative Reductions
SEE
History Pruning
Countermove Heuristic
Killer Heuristic
Castle Extension
Check Extensions
Recapture Extensions
Singular Extensions
History Extensions


--------------------
ENGINES THAT INSPIRED ME
--------------------

Laser, Koivisto, Cheng, Ethereal, Xiphos, Berserk, Marvin-Chess, Stockfish (old versions, no NNUE).

Download: https://drive.google.com/file/d/1mlb8Ow ... share_link

Cheers...

[Graham Banks]

Is it open source?

Author nationality?

[carotino]

Hi! I'm italian, I live in a small village at the foot of the Dolomites.

[carotino]

The engine is free but, currently, it's not open source.

[carotino]

In the end game Tenax tries to give the rook for a knight, but unfortunately it wasn't enough to win...

[Event "My Tournament"]
[Site "?"]
[Date "2023.04.12"]
[Round "10"]
[White "komodo-14.1-linux"]
[Black "tenax-0.7.8-x86_64"]
[Result "1/2-1/2"]
[ECO "C23"]
[GameDuration "01:28:08"]
[GameEndTime "2023-04-12T23:58:48.767 CEST"]
[GameStartTime "2023-04-12T22:30:39.806 CEST"]
[Opening "Bishop's Opening"]
[PlyCount "112"]
[Termination "adjudication"]
[TimeControl "40/1800"]
[Variation "Calabrese counter-gambit, Jaenisch Variation"]

1.e4 e5 2.Bc4 f5 3.d3 Nf6 4.Nf3 fxe4 5.dxe4 Bb4+ 6.c3 Bc5 7.b4 Bb6 8.O-O d6 9.a4 a5 10.Ba3 Qe7 11.Nbd2 Nc6 12.Rc1 Bg4 13.h3 Bh5 14.Qb3 Nd7 15.Bd5 Rf8 16.Rb1 Nd8 17.bxa5 Rxa5 18.Bb4 Ra7 19.Ra1 Bc5 20.a5 Qf6 21.Qc4 c6 22.Bg8 Qh6 23.Qa2 Ke7 24.Bc4 b5 25.Bb3 Nb7 26.Bd1 Nxa5 27.Qb2 Rfa8 28.Nh4 g6 29.Bxh5 Qxh5 30.Nhf3 Qh6 31.Bxc5 Nxc5 32.c4 bxc4 33.Ra3 Ra6 34.Rfa1 Nab3 35.Rxa6 Rxa6 36.Rd1 Nxd2 37.Nxd2 c3 38.Qxc3 Qf4 39.Qc2 Ra4 40.Nc4 Qxe4 41.Qd2 d5 42.Nb6 Qf4 43.Nxa4 Qxd2 44.Rxd2 Nxa4 45.Ra2 Nc5 46.Kf1 d4 47.Ke2 e4 48.Kd2 Nd7 49.h4 c5 50.h5 gxh5 51.Ra5 h4 52.Ra6 c4 53.Kc2 h5 54.Ra5 Ke6 55.Rxh5 c3 56.Rxh4 Nc5 1/2-1/2

[carotino]

CHANGES:

- fix some bugs
- improved search stability
- adjust time management
- search tuning
- adjust space Eval

https://drive.google.com/file/d/1TTEoBR ... share_link

[carotino]

----------------------
Ver. 0.8.0 CHANGES
----------------------

- correct a serious shortcoming in King Safety
- correct some little bugs
- added bonus for Rook opposite King (and adjacent lines)
- fixed some tables in eval.c


Download: https://drive.google.com/file/d/1nD2Ra8 ... share_link

[Event "Tenax test"]
[Site "?"]
[Date "2023.04.23"]
[Round "1"]
[White "tenax-0.8.0-x86_64"]
[Black "Pedone_linux_sse42"]
[Result "1/2-1/2"]
[ECO "C63"]
[GameDuration "00:26:11"]
[GameEndTime "2023-04-23T10:47:31.590 CEST"]
[GameStartTime "2023-04-23T10:21:20.179 CEST"]
[Opening "Ruy Lopez"]
[PlyCount "69"]
[Termination "adjudication"]
[TimeControl "40/900"]
[Variation "Schliemann defense"]

1.e4 e5 2.Nf3 Nc6 3.Bb5 f5 4.d3 fxe4 5.dxe4 Nf6 6.O-O d6 7.Bc4 Bg4 8.Be3
Qd7 9.h3 Bh5 10.Nc3 Be7 11.Be2 Bg6 12.Nh4 Bf7 13.Nf5 O-O 14.f4 exf4 15.
Rxf4 Rae8 16.Qd2 Bd8 17.Raf1 Be6 18.Bb5 a6 19.Bxc6 bxc6 20.Qd3 Nxe4 21.
Nh6+ gxh6 22.Rxf8+ Rxf8 23.Rxf8+ Kxf8 24.Bxh6+ Ke8 25.Qxe4 Bf6 26.Qa4 Kd8
27.Ne4 Bxb2 28.Bg5+ Kc8 29.c3 Bf5 30.Qxa6+ Kb8 31.Qa4 Qe6 32.Nxd6 cxd6 33.
Qb4+ Kc7 34.Qa5+ Kc8 35.Qa6+ 1/2-1/2

[Graham Banks]

I'm already 100 games into a 0.7.9 gauntlet, so I'll finish that before looking at later versions.

[carotino]

Thx for Your testing, Graham.
Apologies for the quick version updates, but these days I had a lot of free time, so I worked on the engine.

The version 0.8.0 is now quite stable because I fixed several bugs and glitches.

[benkrik]

Hi, somehow it seems that 0.8.0 is 100 Elo or more weaker than 0.7.8 or 0.7.9 both in self-play and in tournaments. Also Stefan Pohl aborted testing of Tenax 0.8.0 as it's too weak. As 0.7.8 and 0.7.9 are not available anymore I guess he never had chance to test those stronger versions.

In my tests 0.7.9 would have similar relative strength as in ccrl ratings , and 0.7.8 seems to be even 10-15 ELO stronger, but 0.8.0 comparing to the older versions is not as good. Does anybody else have the similar results?

Any comments from the author?

[carotino]

After correcting the previous bugs, at the last moment I wanted to insert some "improvements", without doing any serious tests.
Only verification: my belief that the engine would have "definitely" been stronger...

Everything will be fixed in the next release (I hope!).

[benkrik]

Happens to the best of us Waiting for the next version, thank you for the engine!

[carotino]

This version is still in beta testing, but is stable.
Executable for Windows and Linux

Changes:
-------------
- correct various bugs
- added bonus for Rook opposite King (and adjacent lines)
- fixed the PSQT tables in eval.c
- improving aspiration window
- add compilation for PEXT and AVX2


Download: https://drive.google.com/file/d/1yOm3kL ... drive_link

Cheers.