Arasan in ACCA

[jdart]

Arasan scored 3/6, which is about where it's usually wound up in these tourneys. I think it was a bit unlucky against equal or lower opponents, but that's life.

Arasan has had a lot of code changes over the past 6 months. The main thing has been that it's using magic bitboard code now, not rotated bitboards (I see Crafty has been through the same evolution). It is faster/simpler. The SMP support is much more solid now. Arasan 10.4 is prone to crash in SMP mode but not the new version (11.0). I have taken the lock off the main hash table (thanks to Bob Hyatt for discussions about how/why to do this), so it is hitting much higher NPS now: up to 4 million NPS on my quad. And there are a bunch of eval and search changes.

I will probably release this version soon. I had hoped to do some fixes to the Arasan Windows UI too (although probably nobody on this forum uses that), but have only done a little cleanup on that.

Anyway, in the recent ACCA tourney Arasan beat its first round opponent handily. In the next round it lost badlly to Naum. It played into a bad book line, but probably didn't have much chance anyway. It then won a nice game against Telepath, which was decided by a sudden kingside attack (Telepath didn't see it coming).

Against Tinker it was out of book very early. I had changed the book recently to allow the B22 Sicilian (early c3), but it isn't tuned very well to play that. I should learn to leave the book alone before a tourney. In the Tinker game Arasan was much worse but managed to get into a fortress draw.

Last 2 games were against DeltomateX and Swaminathan (Slowchess). Arasan had a score over +3 against DeltomateX at one point and I think it could have won, but it made an error and got only a draw. It was out of book again early against Slowchess and made some positional errors. In the endgame Slowchess had an extra pawn: Arasan had chances to draw the endgame I think, but it lost. Good game by Slowchess.

The final 3 games are annotated here, with some help from Rybka and Shredder (but I haven't done a really deep analysis, and so there may be errors):

http://www.arasanchess.org/games.shtml

--Jon