At last, the first “stable” release of my chess engine. The main new features are:

• Static Exchange Evaluator (SEE): the biggest change,  affects move ordering introducing more move generation phases, also affects LMR, etc.
• New “experimental” evaluation function, with King Safety, X-Ray attacks and improved mobility
• Recapture extension, also changed a lot the extension mechanics adding fractional extensions
• Quiescense search now only generate checks the first 4 PLYs and follows only good captures
• UCI Options: can configure Hash Size, Book, LRM, IID, extensions, the evaluator to use, etc.
• Bugs with draw detection by the 50 move rule (I was doing at 50 PLY), and lots of other small bugs solved

Finally the Negascout code did not improve results at tournaments, so all the Negascout code is commented in the SearchEngine. I’ll continue to investigate.

With this release I include an package to run the program from chess GUIs like Arena, so now it can be included in “official” tournaments.

ELO at tests had a big increase from last version. Now scores over 2330 ELO points at BT2630 test (from the 2100 of Carballo 0.2). Also the positions solved of the “win at chess” test are now 275 of 300 (from the previous 237/300), well, also helped that the EPD parser had a bug and didn’t work well with positions with more than one solution. In LCT II also scores 2300 ELO. All the tests results are in the SVN, at the folder “testresults”.

But at tournament (playing against other java chess engines), the improvement is not so much. Now I think is over BrembroCE, but remains behind Jonathan Pettersson’s Mediocre, Alf and Frank Walter chess engines. I will center the next testing in tournament play.

Play Against Carballo Chess Engine

Two months ago I read a post about Toledo Nanochess in Microsiervos, and remembered my failed attemps to make a chess program in Pascal/Assembler when I was younger. So 13 years later I wrote my chess program from scratch in Java. I did it in two months at after-hours, reading a lot at the Chess Programming Wiki, and here is the result:

Play Against Carballo Chess Engine

It is a work-in progress, but a good framework to test some ideas in chess programming and good enought to play some interesting games against it (well, actually I am not able to win it, but I am a very poor chess player).

Now I’m mounting my kitchen from Ikea, so I haven’t time to improve Carballo, but in a near future I’ll continue working on it.