The way all of these were done was to make such positions worse for Crafty. Just pulling the scores closer to zero is the wrong thing to do in many cases. Because many near-zero scores are just numbers representing approximate equality, even though there are imbalances that might create a struggle later. These kinds of positions are more absolute in their evaluation, which means it would be nice to have a "absolute draw" vs "probably a draw" type scoring. I would much prefer "probably a draw but with some winning chances for my side (and not the opponent's)" over "absolutely drawn because it is locked up."Tony wrote:Why would this be asymmetrical ? Shouldn't you just pull the score closer to zero if the "loosing" side has the choice to wall ?bob wrote:One day, if I can figure out how to do that without any sort of asymmetrical behavior, I will do that. But we removed _all_ asymmetry in the eval when we started the rewrite last year or the year before, and we don't want to regress to that solution for certain types of problems...CThinker wrote:Dann posted an example of how your old code could be effective at certain positions. Maybe it is worth bringing it back?bob wrote: It was an asymmetric evaluation term and all of that was eliminated within the last 2 years.
Also it did not do what Gerd is looking for. It was an almost exact match, where at least 3 of the 4 pawns had to match. He is looking more general than that I believe, with some measure between 0 and 100 of how well the match fits...
Tony
The other part was the Stonewall detection and that was completely asymmetric, being always a big penalty for Crafty so that it would just avoid that type of position completely if possible.