search

sandermvdb / chess22k

Chessengine written in Java
GNU General Public License v3.0
31 stars 8 forks source link

Screwed detection #3

Closed ratosh closed 6 years ago

ratosh commented 6 years ago

If i understood screwed detection serves to detect pieces that you can capture when giving a safe check. It does not detect screwed pieces that are not behind the king: 3k4/8/8/8/7r/2B5/8/K7 w - -

It may be detecting screwed pieces that could be defended by the king: 1r1k4/7R/8/8/8/8/8/K7 w - -

sandermvdb commented 6 years ago

Screwed pieces are indeed skewed pieces ;)

The reason it does not detect pieces that are not behind the king is that I would need to calculate all possible moves/x-rays when giving a safe check. At the moment this is not necessary. (I only calculate sliding moves from king position and check if king is in between a sliding piece and a screwed pieces).

It does not detect screwed pieces that are defended by the king if the king needs to make 2 moves. This would require a new KING_2_MOVES lookup table. I implemented this but the eval error result was only marginally better so I am leaving this out.