I’ll let my Pull Request notes (PR 3) explain where I began and where I finished (hint: not where I expected) with my latest code improvements to MadChess 3.0 Beta:
Originally, I intended this PR to add Static Exchange Evaluation (SEE) to MadChess’ search method to reorder or skip evaluation of captures and / or quiet moves that enable the opponent to profitably capture the most recently moved piece. After numerous attempts to write a method that evaluates piece exchanges- either statically (without actually moving pieces) or dynamically (move pieces and search), and integrate it into the search, I could not find any technique that improved the engine’s playing strength. I decided to leave in the
Search.GetExchangeScore method (dynamic evaluation of piece exchanges) and associated
analyzeexchangepositions UCI commands even though exchange score is not considered by the main search nor the quiet (quiescence) search.
I could not find any SEE technique that improved the engine’s playing strength.
In addition, this PR contains numerous tweaks to search logic and tuned evaluation parameters; and it contains numerous code performance and clarity improvements. Together, these changes account for a 30 ELO improvement in playing strength. MadChess 3.0 Beta, even with its primitive evaluation function (simple endgames, material, piece location, passed pawns, and piece mobility) now plays stronger (2450 ELO) than MadChess 2.2 (2443 ELO), at least at bullet time control.
|Eval Param Tuning||Evaluation||2020 Jul 23||bef88d5||283||2450||+30|
|Late Move Pruning||Search||2020 Feb 08||6f3d17a||288||2420||+29|
|Piece Mobility||Evaluation||2020 Feb 01||5c5d4fc||282||2391||+62|
|Passed Pawns||Evaluation||2018 Dec 27||103||279||2329||+119|
|Staged Move Generation||Search||2018 Dec 15||93||275||2210||+39|
|History Heuristics||Search||2018 Dec 03||84||275||2171||+28|
|Eval Param Tuning||Evaluation||2018 Nov 24||75||272||2143||+47|
Material and Piece Location
|Baseline||2018 Nov 08||58||269||2096||0|
- GitHub commit (hash) or Subversion source code revision (integer)
- Win At Chess position test, 3 seconds per position
- Bullet chess, 2 min / game + 1 sec / move