JudaS ++ is a free and strong UCI chess engine derived from Stockfish that analyzes chess positions and computes the optimal moves. JudaS ++ does not include a graphical user interface (GUI).
Eubos chess is a multi-threaded Java chess engine. Eubos uses a standard alpha-beta negascout algorithm with transposition hashing and quiescence search extension. It uses lazy move generation and lazy evaluation.
The evaluation function takes account of the following factors
material balance
piece mobility
pawn structure
king safety
tactical threats
It knows about draws by 3-fold repetition and insufficient material.
Lozza was primarily created for use in browsers, but can also be used with traditional chess UIs via Node.js and on pretty-much any platform (see below). Note however that Lozza is relatively slow compared to compiled engines of a similar design, which also makes her relatively weak.
This is a Lozza 4 re-release.
The original Lozza 4 release caused problems for some users. For those that ran it successfully, results (e.g. CCRL Blitz) can stand because no peformative changes have been made. However, please replace with this re-release anyway; thanks.
Please use a recent version of Node if possible (they are always improving performance). The latest stable version is 22.
Train generation 3 net. Use ADJACENT, not DIST. Simplify QS and don’t go into QS if in check. Scale eval by 1.9. Scale UCI cp by 1.9. Add perspective (currently unused). Use the Mersene Twister from cwtch for randoms. Move futility alpha test to move loop. Use hash move in QS. Optmise deferral of accumulator update a bit more. Fix some web stuff. Add improving indicator (failed to get it to gain so far). Prune QS with quickSee(). Only count nodes that iterate moves. Put eval in TT before search. Optimise castling a bit. Simplify search recursion. Allow successive NMP and beta pruning. Bigger net 768x128x1 srelu. Make sure all UE updates (e.g. castling) are a single accumulator loops. Defer UE to after legal check (doh!) and don’t check pre-determined legal moves. Minor tweaks for datagen + net command.
This script will prompt you for beginning and end year/month, then download everything you ask for, extract each one, and filter each one in pgn-extract according to certain criteria that can be changed.
This is what the file pgn-extract-command.txt looks like:
Anything from -t to -w can be changed. For instance, if you want to change the minimum and maximum moves — or to take one or both parameters out, here’s the place to do it. If you want to take out the requirement that a game end in checkmate, just take out the –checkmate option. The –evaluation option is what creates those evaluations for each move. The -w9999 is what makes each movelist one line. -D checks for doubles, -e specifies that you want ECO information and opening names. (Which is what eco.pgn is for.) If you want to change the contents of tags.txt, you’d either be changing the minimum Elo for either white or black, or the minimum time control — or taking any of those requirements out. The roster.txt file is a list of tag names, one per line, that define the order those tags go in. Specifying –xroster means that it will remove any tags *not* in the roster, as well as put them in the same order.
Because this script needs pgn-extract.exe to run, it’s necessary to keep the binary and all of its dependent files in the same directory as the script.
This is a C program written by ChatGPT o1, at my direction. To be clear, I know nothing about coding, especially in a low-level language. The form that the command takes is:
It should be run in the same directory as the executable, at least for the command to take the form above. If you wanted, you could have each path be a full path. If there are any spaces in the path, you should surround it with double quotes.
It should be noted that because this is written in C and optimized for speed, it runs bizarrely fast. It finishes a gigabyte in about two seconds. It should also be noted that for the same reasons, it’s just going to do it, and not check to make sure there’s enough room. So if you are filtering a very large PGN, make sure you have enough space and resources.
If you simply double-click on the file, it should prompt you for a few things, like the PGN or the path to a directory, for games to convert, the time it takes per move, the color of the board, and… I guess that’s all. Point is, all you need to bring is the path to your PGN(s). It should do the rest. Here is a raw PGN that I’m using as a source in this case:
[Event "Casual game"][Site "London ENG"][Date "1851.06.21"][EventDate "?"][Round "?"][Result "1-0"][White "Adolf Anderssen"][Black "Lionel Adalbert Bagration Felix Kieseritzky"][ECO "C33"][WhiteElo "?"][BlackElo "?"][Source "La Régence, v3 n7, July 1851, pp221-222"][SourceNote "ends 19.Ke2"][Source2 "The Chess Player, vol.i no.1, 1851.07.19, p.2"][PlyCount "45"]1.e4 e5 2.f4 exf4 3.Bc4 Qh4+ 4.Kf1 b5 5.Bxb5 Nf6 6.Nf3 Qh67.d3 Nh5 8.Nh4 Qg5 9.Nf5 c6 10.g4 Nf6 11.Rg1 cxb5 12.h4 Qg613.h5 Qg5 14.Qf3 Ng8 15.Bxf4 Qf6 16.Nc3 Bc5 17.Nd5 Qxb2 18.Bd6Bxg1 {It is from this move that Black's defeat stems. WilhelmSteinitz suggested in 1879 that a better move would be18... Qxa1+; likely moves to follow are 19. Ke2 Qb2 20. Kd2Bxg1.} 19. e5 Qxa1+ 20. Ke2 Na6 21.Nxg7+ Kd8 22.Qf6+ Nxf623.Be7# 1-0
And here is a GIF produced with this program in green at 1s per move:
