Zahak

A UCI compatible chess AI written in Go. Still work in progress.

Courtesy to the OpenBench community, Zahak is now part of the official OpenBench instance

The name

Zahak (or Zahhak or Azhi Dahak) is an evil figure in Iranian/Kurdish/Perisan mythology, evident in ancient Iranian folklore as Azhi Dahāka, the name by which he also appears in the texts of the Avesta. Legend has it, that he had two giant snakes on his shoulders and he had to feed them two human brains on daily basis, you can read more about him here

Play Zahak online

Zahak is new to LiChess, you can play him and be impressed with him. His LiChess handle is zahak_engine.

Play Zahak on your Android Phone/Desktop

Zahak is a bare chess engine AI, that means it doesn't come with any GUI interface. That also means, it is easy to plug it into any chess GUI that supports UCI protocol.

Tournaments

Zahak recently got invitation to the TCEC tournament!

Zahak is also participating in ZaTour tournament series for open source and original chess engines. And many other tournaments, like the ones arranged by the amazing Graham Banks.

Rating

Zahak is in almost all major rating lists, here are the details:

CCRL rating list

version	CCRL Blitz Rating	CCRL Blitz (8CPU) Rating	CCRL 40/40 Rating	CCRL 40/4040 (4CPU) Rating
9.x	3278	3406	3213	3282
8.x	3133	N/A	3098	N/A
7.x	2964 (32 bit: 2897)	N/A	2938	3006
6.x	2833	N/A	2800 (unstable rating)	N/A
5.0	2730	N/A	2676	N/A
4.0	2570	N/A	2568 (unstable rating)	N/A
3.0	2407	N/A	N/A	N/A
2.0.0	2105 (unstable rating)	N/A	N/A	N/A
1.0.0	2011	N/A	N/A	N/A
0.3.0	1922	N/A	N/A	N/A
0.2.1	1824	N/A	N/A	N/A

CEGT rating list

version	CEGT 40/4 Rating	CEGT 40/20 Rating	CEGT 5"+3' Rating (Ponder On)
9.x	3182	3162	3199
8.x	3046	3022	3051
7.x	2840	N/A	2858
6.x	2664	N/A	2676
5.0	2553	N/A	N/A
4.0	2417	N/A	N/A

Other well-known rating lists

version	GRL 40/2 Rating	SPCC Rating	BRUCE Rating	Fast GM 60+06	Fast GM 10m+6s
9.x	3244	3273	3283	N/A	3138
8.x	3140	N/A	3169	N/A	3057
7.x	2929	N/A	2981	2749	N/A
6.x	2785	N/A	2841	2584	2720
5.0	2686	N/A	2683	2505	N/A
4.0	2522	N/A	N/A	N/A	N/A
3.0	2378	N/A	N/A	N/A	N/A

Implemented Features:

Core Features

UCI Support
(Magic) Bitboards
Multi-stage move generation
Transposition Table
Pawnhash
PolyGlot opening book
Compliant with OpenBench
Syzygy Support
MultiPV
Skill Levels, 1 to 7 (strongest)

Search

Basics

Alpha-Beta search
Quiescence Search
Iterative Deepening
PV Search and PV
Search with Zero Windows
Aspiration Window with PVS
Pondering
Multi-Threading (LazySMP)

Move Ordering

Hash move
Promotions
Static Exchange Evaluation followed by LVA-MVV for equal captures according to SEE
Killer Moves Heuristics
Countermove Heuristics
Move History Heuristics
Countermove History Heuristics
FollowUp History Heuristics

Selectivity

Late Move Pruning
Null-Move Pruning
Delta Pruning
Reverse Futility Pruning
Futility Pruning
Late Move Reduction
Razoring
Check Extensions
Internal Iterative Deepening
SEE pruning both in QS and normal search
Threat Pruning
Singular Extension
Multi-Cut

Evaluation

NNUE

Command line options

bash-3.2$ bin/zahak -help
Usage of bin/zahak:
  Commands:
   ./zahak         Runs Zahak in UCI mode
   ./zahak bench   Runs Zahak in OpenBench mode
   
  Options:
  
  -book string
        Path to openning book in PolyGlot (bin) format
  -perft
        Provide this to run perft tests
  -perft-tree
        Run the engine in prefttree mode
  -gen-epds
        Generate opening EPDs for self-play
  -profile
        Run the engine in profiling mode
  -slow
        Run all perft tests, even the very slow tests
  -test-positions string
        Path to EPD positions, used to test the strength of the engine

Skill Levels

Anchored around Rustic Alpha 3, I found that, based on CCRL the ratings will probably translate to the following:

Skill Level 1: 1270
Skill Level 2: 1440
Skill Level 3: 1630
Skill Level 4: 1856
Skill Level 5: 2004
Skill Level 6: 2074

Opening Books

Currently only PolyGlot is supported. Then engine doesn't come with any books, but you can attach your favourite one easily by passing the path to -book command: zahak -book PATH_TO_BOOK.

A bunch of free books are available here

Training Networks

Please refer to this guide.

Building

To build the project, simply run make build, testing with make test, and running with make run. Other features exist, for example you can run perft with ./zahak -perft or profile it with ./zahak -profile. You can also run it in perfttree mode with ./zahak -preft-tree.

Contributors

Thanks to the following for their valuable contributions:

Basti Dangca: for generating data for training Zahak's network
Alan Cooper (Scally): for generating weaker networks for different skill levels.

Acknowledgement

Zahak wouldn't have been possible without:

VICE videos
Chess Programming Wiki
The official OpenBench instance, and the all the hardware donators (noopwn4ftw and others)
Aryan Parekh the author of Bit-Genie, who helped me with NNUE
Niels Abildskov the author of Loki, who helped me with Texel Tuning
Nasrin Zaza for the amazing logo
OpenSource engines like: Weiss, Ethereal, CounterGo, Cheng and Berserk (in no specific order)
OpenBench community on Discord
No4b for helping me with some evaluation terms

amanjpro / zahak Goto Github PK

zahak's Introduction