Texel 1.03

[petero2]

Version 1.03 of my chess engine Texel is now available for download from http://dl.dropboxusercontent.com/u/89684995/texel103.7z

The largest user visible changes are SMP support, MultiPV support and a re-tuned evaluation function which makes the engine play more aggressively.

There are 7 compiled versions included:

texel-arm : For the armv7-a architecture. Should work on most modern android devices.
texel32.exe : For 32-bit windows systems with SSE42 and POPCOUNT.
texel32old.exe : For 32-bit windows systems without SSE42 and POPCOUNT.
texel64 : For 64-bit linux intel systems with SSE42 and POPCOUNT.
texel64.exe : For 64-bit windows intel systems with SSE42 and POPCOUNT.
texel64amd.exe : For 64-bit windows systems with SSE42 and POPCOUNT.
texel64old.exe : For 64-bit windows systems without SSE42 and POPCOUNT.

Texel 1.03 scores about 66% (+112 elo) against Texel 1.02 on my linux computer at very fast time controls, using one core.

Changes meant to improve playing strength:
- Multi-threaded (SMP) search.
- Remove moves before the last zeroing move from the repetition history list before starting search.
- Removed bogus transposition table store in Search::iterativeDeepening().
- Disable aspiration window logic when searching for a faster mate.
- Added null move verification search.
- Prefetch entries from the main transposition table.
- Bonus for candidate passed pawns.
- Skip move ordering after enough moves to trigger LMP have been searched.
- Implemented pawn storm bonus for opposite castling positions.
- Removed the Botvinnik-Markoff extension.
- More aggressive LMR.
- Added knowledge for KBpKB, KNpKB, KBpKN and KNpK endgames.
- Store endgame flag in material hash table.
- Optimized lots of evaluation function parameters.
- More consistent evaluation of different classes of pawnless endgames. KQK, KRK, KQKM, KBBK, KBNK, KQKR, KQKMM, KMMKM (M = B or N).

Other changes:
- MultiPV-support.
- Mate distance pruning.
- Evaluation correction for 7 knights vs 3 queens.
- Display engine evaluation using "info string" when starting search in analysis mode.
- Changed internal parameter handling to make it easier to switch between UCI parameters and compile-time constants.

Enjoy!

[velmarin]

You can not say you were stopped.

Great job.
You have to waste time and enjoy it.
Thank you.

[Mike S.]

Thanks! This is an impressive list of improvements and enhancements. I hope to see Texel in the upcoming nTCEC Season 3?

[El Gringo]

Hi,

First tests STS 1-14

Code: Select all

Texel 1.03 x64 	90	85	88	80	69	75	71	73	72	74	76	84	83	80	1100
Texel 1.02 x64	84	77	71	75	73	77	70	65	58	69	74	80	76	67	1016

[Graham Banks]

Excellent news. Thanks Peter.

[Sedat Canbaz]

Many thanks Peter!

Right now your previous version is playing in my newest Scratch testing, but anyway so far Texel's performance is very good!

[petero2]

Hi,

First tests STS 1-14

Code: Select all

Texel 1.03 x64 	90	85	88	80	69	75	71	73	72	74	76	84	83	80	1100
Texel 1.02 x64	84	77	71	75	73	77	70	65	58	69	74	80	76	67	1016

Thank you, this looks pretty good.

I have never studied the STS test suite before, but it looks like it could be a source of inspiration for evaluation function improvements to test.

On a side note I would be very interested to see how texel 1.03 compares to 1.02 and to other engines in a similarity test. I have developed a special optimization program that computes all parameters in the texel evaluation function. Not a single value was decided by me. Even though I sometimes felt the urge to "correct" some of the values that looked weird to me, I managed to resist.

[petero2]

Thanks! This is an impressive list of improvements and enhancements. I hope to see Texel in the upcoming nTCEC Season 3?

Yes, that is the plan.

[tpetzke]

I have developed a special optimization program that computes all parameters in the texel evaluation function. Not a single value was decided by me. Even though I sometimes felt the urge to "correct" some of the values that looked weird to me, I managed to resist.

Welcome to the club

Thomas...

[Graham Banks]

For anybody interested, I'm running a short 10 game match between Texel 1.03 64-bit and Quazar 0.4 64-bit at the CCRL 40/40 time control in TLCV (GrahamCCRL.dyndns.org 16001).