Chess Engines Diary

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=2016 v. 5.0: ELO Change (self-play) Elo | 113.74 +- 16.13 (95%) SPRT | 60.0+0.60s Threads=1 Hash=64MB LLR | 2.95 (-2.94, 2.94) [0.50, 2.50] Games | N: 1474 W: 787 L: 321 D: 366 Penta | [27, 73, 235, 211, 191] What's Changed Check extension in search by @Dannyj1 in #71 Fix check extension causing less TT hits by @Dannyj1 in #72 Late Move Reduction by @Dannyj1 in #73 Bias tuner towards smaller evaluation values by lowering base values by @Dannyj1 in #74 Tuner: Five-point Stencil Approximation, Train for multiple epochs, accuracy improvements & bug fixes by @Dannyj1 in #76 Fix compilation by @Dannyj1 in #77 Zagreus 4.1 - resul...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=2016 v. 4.1: Elo Change (self-play) Elo | 48.86 +- 6.75 (95%) Conf | 60.0+0.60s Threads=1 Hash=64MB Games | N: 7910 W: 3578 L: 2473 D: 1859 Penta | [296, 495, 1627, 882, 655] What's Changed Fix SEE not handling captures properly by @Dannyj1 in #64 QSearch and Move Generation Improvements (promotions in qsearch, evasions movegen) by @Dannyj1 in #65 Fixed counter move history ordering by @Dannyj1 in #66 Fix QSearch ignoring non-capture promotions by @Dannyj1 in #68 Fixed some issues with insufficient material draws wrongfully being detected when there is sufficient material. Individual statistics: Zagreus 2.0.0 alpha-2 - 105 game...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=2016 (windows) The engine has not yet been tested for Android, first tests coming soon v. 4.0: Another big update! This time I reworked the whole search to be less buggy and more accurate. There seem to be some weaknesses that still need work (especially the endgame), but the engine performs much better now. ELO Change (self-play) Elo | 293.33 +- 28.67 (95%) SPRT | 60.0+0.60s Threads=1 Hash=64MB LLR | 2.95 (-2.94, 2.94) [0.50, 2.50] Games | N: 888 W: 689 L: 78 D: 121 Penta | [3, 7, 74, 96, 264] What's Changed Evaluation of weak squares in mobility and defended minor pieces by @Dannyj1 in #60 Search rework by @Dannyj1 in #61 Ind...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=2016 v. 4.0: Another big update! This time I reworked the whole search to be less buggy and more accurate. There seem to be some weaknesses that still need work (especially the endgame), but the engine performs much better now. ELO Change (self-play) Elo | 293.33 +- 28.67 (95%) SPRT | 60.0+0.60s Threads=1 Hash=64MB LLR | 2.95 (-2.94, 2.94) [0.50, 2.50] Games | N: 888 W: 689 L: 78 D: 121 Penta | [3, 7, 74, 96, 264] What's Changed Evaluation of weak squares in mobility and defended minor pieces by @Dannyj1 in #60 Search rework by @Dannyj1 in #61 Individual statistics: Zagreus 2.0.0 alpha-2 - 105 games (+  7,=  1,- 97),...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=2016 v. 3.0: This is a pretty big update coming with a complete evaluation rewrite, improving performance, improvements to the gradient descent tuner and fixing a good amount of issues. Self-play shows a pretty good ELO change (although the real change against other engines is usually less). ELO Change Elo | 160.52 +- 30.39 (95%) SPRT | 60.0+0.60s Threads=1 Hash=64MB LLR | 1.33 (-2.94, 2.94) [0.50, 2.50] Games | N: 542 W: 347 L: 113 D: 82 Penta | [9, 13, 88, 57, 104] What's Changed Smarter/better time management by @Dannyj1 in #48 Cleanup of search code by @Dannyj1 in #49 Fix TT move sorting by @Dannyj1 in #50 Simplify versioni...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=1999 v. 2.3.1: Elo Change ELO | 44.87 +- 20.14 (95%) CONF | 60.0+0.60s Threads=1 Hash=64MB GAMES | N: 1020 W: 508 L: 377 D: 135 Notes The engine is now a lot more conservative with it's time usage, maybe a bit too conservative. This will be tweaked/tuned in a future release. What's Changed Fix outpost evaluation and pawn attacks not being taken into account during evaluation by @Dannyj1 in #43 Properly handle the movestogo UCI parameter, fix some crashes when games last very long by @Dannyj1 in #45 Time management improves & time forfeit fixes by @Dannyj1 in #47 Multiple crash fixes Reduced the size of Transposition Ta...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz  Rating CEDR=2019 v. 2.2.0: Performance improvements by @Dannyj1 in #32 Properly find optimal K by @Dannyj1 in #31 Outpost evaluation by @Dannyj1 in #33 Multiple bug fixes in move ordering by @Dannyj1 in #35 Performance improvements by @Dannyj1 in #36 Individual statistics: Zagreus 2.0.0 alpha-2 - 105 games (+  7,=  1,- 97),  7.1 % Critter 1.6a                  :   8 (+  0,=  0,-  8),  0.0 % Houdini 1.5a                  :   2 (+  0,=  0,-  2),  0.0 % ECE 20.1    ...

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. Author:Manuel Diaz v. 2.1.0: What's Changed Do an "in check" search extension before dropping into qSearch by @Dannyj1 in #24 Null move pruning by @Dannyj1 in #25 Dynamic LMR reduction by @Dannyj1 in #26 Tuner tweaks by @Dannyj1 in #27 Attacks near king evaluation rework by @Dannyj1 in #29 Fixed some issues in the fail-soft framework Full Changelog: v2.0.0...v2.1.0 Elo Change ELO | 15.61 +- 11.65 (95%) CONF | 60.0+0.60s Threads=1 Hash=64MB GAMES | N: 2984 W: 1367 L: 1233 D: 384 Zagreus 2.1.0 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v. 2.0.0: Tune all evaluation parameters with a stochastic gradient descent tuner by @Dannyj1 in #22 Full Changelog: v2.0.0-alpha-3...v2.0.0 ELO | 71.54 +- 16.76 (95%) SPRT | 10.0+0.10s Threads=1 Hash=64MB LLR | 3.00 (-2.94, 2.94) [0.00, 3.00] GAMES | N: 1640 W: 936 L: 603 D: 101 Zagreus 2.0.0 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v. 2.0.0 alpha-3: Better move ordering by @Dannyj1 in #11 Late move reduction by @Dannyj1 in #12 Improve king safety evaluation by @Dannyj1 in #14 Pawn evaluation by @Dannyj1 in #16 Performance improvements by @Dannyj1 in #17 Fixed underflow in time management by @Dannyj1 in #18 Fixed Late Move Reduction reducing early moves by @Dannyj1 in #20 Check search extension by @Dannyj1 in #21 ELO | 309.00 +- 34.12 (95%) CONF | 60.0+0.60s Threads=1 Hash=64MB GAMES | N: 848 W: 708 L: 105 D: 35 Zagreus 2.0.0 alpha-3 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v. 2.0.0 alpha-2: v2.0.0 is a complete rewrite of Zagreus.  SEE capture sorting in quiescence search by @Dannyj1 in #8 Time management enhancements by @Dannyj1 in #9 No mobility on pawn attacks by @Dannyj1 in #10 Fixed promotions not being detected from the position command, causing illegal moves to be made after promotions Fixed some bugs Zagreus 2.0.0 alpha-2 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v.1.1.: Reworked the search algorithm. Null Move Pruning isn't working properly yet, so I removed it for now. A lot of bugs were fixed in this search rework, so I found this update worth releasing anyway. Fixed an issue with UCI options not properly reporting a max value Changed the way Zagreus evaluates material balance Fixed an issue where endgame mobility was calculated in the midgame and vice-versa Bonus for pushing pawns towards promotion in the endgame (#2) Slight tweaks to mobility evaluation values (#3) Remove development score (#4) Zagreus 1.2.0 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v.1.1.: Proper MVV/LVA implementation Changes to mobility evaluation Improve performance of TT Added a MovePicker to avoid unnecessary sorting. Pretty big performance boost. Fixed Transposition Table not being used at all. It was also not implemented correctly Fixed PV move sorting Fixed multiple evaluation bugs Fixed endgame PSTs not being used in the endgame . Zagreus 1.1.0 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v.1.0.1: It appears that 1.0.0 wasn't as stable as I had thought. Fixed an issue with zobrist hashes being incorrect after losing castling rights Fixed an issue with zobrist hashes being incorrect after castling Fixed incorrect zobrist hashes being used while ordering move, thus causing more nodes to be searched than needed and potentially wrong nodes being pruned. Zagreus 1.0.1 download

Zagreus is a work in progress UCI Chess Engine. You can play against Zagreus on Lichess: https://lichess.org/@/Zagreus_Engine. You will also be able to find it's elo rating on there. At the time of writing this is around ~1800 rapid.  Zagreus is a constantly changing engine with hopefully an increase in elo every update. v.0.5: Completely rework the evaluation: Improved speed/performance Certain features are now evaluated in a better way Fixed multiple bugs regarding evaluation Zagreus 0.5 download