Simbelmyne - UCI engine
Rating CEDR=2474
v.1.6.0:
What's new
This release mostly focuses on fleshing out the evaluation function. There's still a couple of things I might add/revisit, but I think this release adds all of the most important evaluation features.
Score of Simbelmyne vs Simbelmyne v1.5.1 (2696): 2114 - 789 - 1409 [0.654]
... Simbelmyne playing White: 1055 - 387 - 715 [0.655] 2157
... Simbelmyne playing Black: 1059 - 402 - 694 [0.652] 2155
... White vs Black: 1457 - 1446 - 1409 [0.501] 4312
Elo difference: 110.3 +/- 8.7, LOS: 100.0 %, DrawRatio: 32.7 %
Added features
🔍 Search
Tweak LMR values
⚖️: Evaluation
🔧 Eval refactor
🔧 Split eval up into incremental and non-incremental
Include pawn attacks and pin masks in mobility considerations
Add evaluation term for king tropism wrt. friendly/enemy passed pawns
Add evaluation term for connected rooks
Add evaluation term for rooks on semi-open file
Add evaluation term for major piece on 7th rank
Add evaluation term for queen on (semi-) open file
Add evaluation term for threats (pawn on minor/rook/queen, minor on rook/queen, rook on queen)
Add evaluation term for rook and bishop outposts
Add contempt factor to reduce number of early draws
Add Tempo bonus
🐛 Bugfixes
Fix PV reporting, finally
Don't double-count leaf nodes in negamax and quiescence search
Fix bug where we were wrapping around the board looking for phalanx pawns
💬 UCI
print properly formatted mate scores in UCI output (score mate n)
Pretty print UCI messages when attached to a tty
Add custom eval command that pretty-prints a breakdown of the evaluation
Misc
🔧 Pre-load a board position through a -f/--fen cli argument
See the respective PRs for self-play results where relevant
Choosing a binary
This release comes with precompiled binaries for all major platforms. Because the engine benefits tremendously from more modern CPU instruction sets, there are binaries compiled for major instruction sets, following the x86-64 microarchitecture levels as a naming scheme.
Realistically, on modern hardware (< 10 years old), you should be okay to use the binaries labeled V3. If the engine crashes within the first seconds, try V2, and so on.
What's Changed
Fix pv reporting by @sroelants in #172
Pretty print UCI messages by @sroelants in #173
Add show uci command by @sroelants in #174
Take a cli argument to pre-load a desired position by @sroelants in #175
Pretty print eval by @sroelants in #176
Eval refactor by @sroelants in #178
Eval/non incremental eval by @sroelants in #179
Eval/mobility minus pawn attacks by @sroelants in #180
Eval/king friendly passers by @sroelants in #181
Add eval term for connected rooks by @sroelants in #182
Add eval term for rook on semi-open file by @sroelants in #183
Add "Major on 7th rank" eval term by @sroelants in #184
Add eval term for queen on (semi-) open file by @sroelants in #185
Add helpers for shifting bitboards around by @sroelants in #186
Eval/fix phalanx bug by @sroelants in #187
Eval/refactor incremental context by @sroelants in #188
Use fixed phalanx-pawn bonus by @sroelants in #189
Swap connected_pawn for protected_pawn by @sroelants in #190
Eval/threats by @sroelants in #191
Add knight and bishop outposts by @sroelants in #192
Make insufficient material marginally more efficient by @sroelants in #193
Add manual contempt factor by @sroelants in #194
📈 Add tempo bonus by @sroelants in #195
Reduce bad captures more by @sroelants in #196
Simbelmyne 1.2.0 - results:
| Catto 0.1.0 | 4/4 | +4 | 4 Games |
| Sheep 1.0 | 4/4 | +4 | 4 Games |
| Fatalii 0.6.0 | 2/4 | +0 | 4 Games |
| Lynx 1.2.0 | 0.5/4 | -3 | 4 Games |
| Shuffle 5.0.0 | 0.5/4 | -3 | 4 Games |
| RubiChess 20240112 | 0/4 | -4 | 4 Games |
| Caissa 1.16 | 0/4 | -4 | 4 Games |
| Counter 5.5 | 0/4 | -4 | 4 Games |
| Minic 3.41 | 0/4 | -4 | 4 Games |
| Avalanche 2.1.0 | 0/4 | -4 | 4 Games |
| Texel 1.11 | 0/4 | -4 | 4 Games |
| Uralochka 3.41 dev1 | 0/4 | -4 | 4 Games |
| Arasan 24.1 | 0/4 | -4 | 4 Games |
| Cheng 4.43 | 0/4 | -4 | 4 Games |
| Pawn 3.0 | 0/4 | -4 | 4 Games |
| Sloth 1.6 | 2/2 | +2 | 2 Games |
| Oxidation 0.5.0 | 2/2 | +2 | 2 Games |
| Dragonrose 0.21 | 1.5/2 | +1 | 2 Games |
| Blocky 1.0.0 | 1.5/2 | +1 | 2 Games |
| Pingu 3.0.0 | 0.5/2 | -1 | 2 Games |
| Leptir 100124 | 0/2 | -2 | 2 Games |
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