DiscoCheck 5.2

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lucasart
Posts: 201
Joined: Mon Dec 17, 2012 1:09 pm
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DiscoCheck 5.2

Post by lucasart » Sat Jan 11, 2014 2:09 am

Here is a new version of my engine, DiscoCheck.

I've attached some compiles (Linux and Windows 64-bit). As usual, SSE4.2 compiles are for modern CPU, and SSE2 are slower but compatible with older CPU:

The source code is also available, on my github page:
https://github.com/lucasart/chess/releases

It scores +58 elo against DiscoCheck 5.1, at fast time control 6"+0.05". Probably +40 elo in rating list conditions (ie. against unrelated opponents and at much longer time control).

Important changes
  • Update move sorting heuristics only when alpha is raised. This stupid bug was quite a big elo drain.
  • Passed pawn tuning: push away more aggressively the enemy king from our passed pawns.
  • Simplify Pawn Piece-Square Table
  • Introduce material imbalance formula, based on counting minor pieces. Re-tune material values in the presence of the new material imbalance.
  • Do not distinguish node type for reduction (PV, Cut, All are always reduced the same way).
  • null search only when depth >= 2. And re-CLOP null search reduction with depth >= 2 precondition.
  • Prune threat refutations, like any other moves.
  • Improve LMR transition (between search and qsearch).
  • Introduce triple reductions.
  • Do not double reduce bad checks.
  • Never prune the first move.
  • Update move sorting heuristics on TT pruning (History, Refutation, Killers).
Enjoy!
Attachments
discocheck_5.2.tar.gz
(612.17 KiB) Downloaded 996 times
"Talk is cheap. Show me the code." -- Linus Torvalds.

Werner
Posts: 12
Joined: Mon Aug 02, 2010 11:06 am

Re: DiscoCheck 5.2

Post by Werner » Mon Jan 20, 2014 12:03 pm

Hi Lucas,
thanks for the engine.
Please have a look at Talkchess.com
http://www.talkchess.com/forum/viewtopi ... 91&t=50965

I have some debug Infos for you.

regards
Werner

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