I added piece mobility evaluation to MadChess 2.0 Beta. The candidate moves of each piece are counted (move legality is not tested) and a non-linear bonus is assigned. Pieces with few moves are penalized. Pieces with many moves are awarded. Assigning a non-linear bonus encourages MadChess to develop all of its pieces, as opposed to maximizing the candidate moves of a few pieces. For example, more centipawns are awarded for increasing the candidate moves of a knight from three to six moves than for increasing the candidate moves of a queen from 14 to 20.
This added 64 Elo to the playing strength of MadChess 2.0 Beta.
MadChess 2.0 1877 : 800 (+208,=134,-458), 34.4 % vs. : games ( +, =, -), (%) : Diff, SD, CFS (%) BikJump v2.01 : 100 ( 13, 17, 70), 21.5 : -204, 12, 0.0 Matheus-2.3 : 100 ( 12, 22, 66), 23.0 : -186, 13, 0.0 Monarch 1.7 : 100 ( 31, 10, 59), 36.0 : -151, 13, 0.0 BigLion 2.23w : 100 ( 30, 15, 55), 37.5 : -127, 12, 0.0 Faile 1.4 : 100 ( 17, 29, 54), 31.5 : -123, 11, 0.0 Sharper 0.17 : 100 ( 43, 9, 48), 47.5 : -104, 12, 0.0 Jabba13032012 : 100 ( 35, 11, 54), 40.5 : -55, 11, 0.0 Roce 0.0390 : 100 ( 27, 21, 52), 37.5 : +16, 10, 94.1
| Feature | Category | Date | Rev1 | WAC2 | Elo Rating3 | Improvement |
|---|---|---|---|---|---|---|
| Piece Mobility | Evaluation | 2014 Dec 16 | 29 | 225 | 1877 | +64 |
| Draw By Repetition Bug | Evaluation | 2014 Dec 10 | 27 | 225 | 1813 | +47 |
| Passed Pawns | Evaluation | 2014 Dec 09 | 26 | 225 | 1766 | +72 |
| Time Management | Search | 2014 Dec 08 | 25 | 231 | 1694 | +24 |
| Delay Move Generation Aspiration Window Bug |
Search | 2014 Dec 02 | 23 | 231 | 1670 | +44 |
| MVV / LVA Move Order Draw By Insufficient Material Move List Overflow Bug |
Search | 2014 Dec 01 | 22 | 235 | 1626 | +30 |
| Tapered Evaluation MG and EG Piece Location |
Evaluation | 2014 Nov 29 | 21 | 234 | 1596 | +107 |
| Alpha / Beta Negamax Aspiration Windows Quiescence, Hash Material, Piece Squares |
Baseline | 2014 Nov 25 | 20 | 236 | 1489 | – |
- Subversion source code revision
- Win At Chess position test, 3 seconds per position
- Bullet chess, 2 min / game + 1 sec / move
I work as a Software Architect at an insurance company. We're building a modern tech stack in the cloud using C#, Azure, ASP.NET Core, Angular, TypeScript, etc.
Thanks a lot for your post. I used your idea of nonlinear mobility in my evaluation in my own engine and it scored 45 Elo!
Cool! Glad to hear the idea benefitted your engine also.
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