Alexandria 9.0.0 - new version chess engine

Chess engine: Alexandria

Author: PGG106 Rating Chess Engines Diary CEDR=3723

We were excited to see the release of the latest Alexandria engine, which has climbed to 6th place on our CEDR ranking list. Version 9.0.0 made its debut in the 1st Chess Engine League – 03/2026 edition, which kicked off today.

Alexandria 9.0.0 what's new?

This release was brought to you by people putting cores on SWE, thanks everyone!

LTC Progression test

Elo   | 28.84 +- 4.40 (95%)
Conf  | 60.0+0.60s Threads=1 Hash=64MB
Games | N: 5060 W: 1553 L: 1134 D: 2373
Penta | [2, 341, 1426, 758, 3]

Progression test was run on the Pohl.pgn book.

Search Changes

Introduced gravity formula for correction history updates
Lowered SBeta on ex pv nodes Lower SBeta on ex Pv nodes
Increased NegExt on cutnodes

Eval Changes

Finally switched to a Multi-layer architecture, with L2=16 and L3=32
Added dual activation to the net architecture
Improved WDL filtering and added piececount filtering in the training process
added a WDL component to loss in the training process
Implemented AddSub for Finny tables
Added NNZ inference (but no permutation step yet)

Alexandria 8.0.0 - results:

Stockfish 17.1	19/39	-1	39 Games
PlentyChess 6.0.5 JA	14/28	+0	28 Games
Berserk 20250307b	12/22	+2	22 Games
Dragon 3.3	10.5/22	-1	22 Games
Berserk 20250606	9.5/20	-1	20 Games
Yuliana 7.0	9.5/20	-1	20 Games
RubiChess 20250606 JA	9/18	+0	18 Games
Cool Iris 14	8/18	-2	18 Games
Lc0 0.31.2	8/14	+2	14 Games
Kookaburra 3.10	7/14	+0	14 Games
Cool Iris v19	7/14	+0	14 Games
DarkSeid 6.2 EE	6/14	-2	14 Games
Obsidian dev-16.14	6.5/13	+0	13 Games
CalvinChess 6.0.0 JA	9/12	+6	12 Games
Stormphrax 6.0.0	7/12	+2	12 Games
Booot 7.4	6/12	+0	12 Games
Green Way	5.5/12	-1	12 Games
Contact 12	5/12	-2	12 Games
Mayhem 8.8 JA	10/10	+10	10 Games
Uralochka 3.42 dev13	7/10	+4	10 Games
Pawnocchio 1.7.2	7/10	+4	10 Games