Barbarossa 0.5.0 released

[nionita]

Hi all,

I just released version 0.5.0 of Barbarossa, which has again many improvements in eval & search, as well as some technical optimizations. In self play it's about 140 elo points better than version 0.4.0.

Barbarossa is the best open source Haskell chess engine.

I created binaries for Win7 (32 bit, 64 bit and 64 bit+SSE4.2), Win10 (32 bit, 64 bit and 64 bit+SSE4.2) and Linux (64 bit and 64 bit+SSE4.2): https://github.com/nionita/Barbarossa/r ... tag/v0.5.0

Functional changes:

In eval:

Optimize eval weights
Mobility calculation change (Stockfish style)
Eval new terms:
-- weak pawns attacks
-- bishop pawns
-- king on pawn(s) - inspired from Stockfish
-- rook on 7th line (when opponent king on 8th)
Simplify king safety, king placement change, king safety sharper formula
Bishop value, SEE piece value changes

In search:

No null move search when STM has no piece
Null move only for depth >= 2 (idea from Sven Schule)
LMR even for extended moves
LMR also in PV node
Correct LMR amplitude: distance to last capture
Don't prune nor LMR passed pawn moves
Search extensions when capturing last queen/rook
When pruning, we want to have at least 1 legal move,
QS: search quiet checking moves - only on frontier and with SEE >= 0
QS: no limit for check escapes, but delta pruning applies
QS: Delta pruning refactoring for speed

Other changes & corrections:

Time management based on logistic regression + corrections & adjustments
Correct return from time abort: do not change tables
Mate score correction
Correct draft statistics
TT update: final only after position search
TT update: best so far exact score as lower limit
Random initialised history (small numbers)

If you have problems with the Win10 versions (like it was in last release), please try the Win7 versions.
Nicu

[CMCanavessi]

Awesome!

[Graham Banks]

Hi all,

I just released version 0.5.0 of Barbarossa, which has again many improvements in eval & search, as well as some technical optimizations. In self play it's about 140 elo points better than version 0.4.0.

Thanks Nicu.