Chess engine: Eubos 2.14

Eubos - a basic Java chess engine, written for kicks. Uses jcpi for the UCI protocol parts. Kind of weak, doesn't evaluate for king safety, for example. Now uses transpostion hashing, but because it runs in the Java VM on a bog standard PC, doesn't search very deeply (around 100K Nodes/s, though this is actually quite hard to evaluate due to the hashing). 

Author: Chris Bolt Rating CEDR=2053

v.2.14

Features

Added evaluation for connected passed pawns

Added full implementation for creating masks of square control, including own piece batteries. In Eubos these are referred to as 'Counted Attack Masks'

Add evaluation for pawn storm and pawn shields into the king safety algorithm

Designed and implemented a new method of efficiently finding positions where there is a passed pawn present, used as a parameter in attack mask computation

Tuning / Optimisation / Tweaks

Revise King Safety evaluation into 3 parts; 1) exposure, 2) vulnerability and 3) mate threat

Counted attack masks are only used for evaluation of positions where there is a passed pawn present, otherwise use simple attacks mask

Don't compute lazy evaluation for alpha threshold, it isn't worth the overhead

Remove prioritisation of pieces attacked by a knight or pawn in the MoveList generation, it isn't worth the overhead

Increase evalaution contribution of piece mobility - this gave a large improvement in playing strength

Fixes

Quality

Refactor the lazy evaluation threshold tuning code

Refactor lazy evaluation into the Position Evaluator class, from the Ply Searcher class

Refactor the Board class to extract a Mobility and Attacks Evaluator class

To install Eubos as an engine in Arena:
1. Select Engines > Install New Engine
2. In the file browser dialog that appears, change the drop down to *.bat
3. Navigate to the Eubos binary location, select the Eubos.bat
4. Select UCI protocol to communicate with Eubos
5. That's it! 

Eubos 2.14 download