Author: Uri Blass
Date: 04:05:30 06/20/04
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On June 20, 2004 at 05:14:26, Joachim Rang wrote: >On June 20, 2004 at 00:12:22, Uri Blass wrote: > >>Is it correct that fruit evaluates mobility as the same for all directions? >> >>If I understand Fruit1.5's code correctly I do not see difference between >>mobility of rook in files and in ranks. >> >>The mobility score for rook seems to be the number of square that it can goto >>minus 7. >> >>Uri > >That is how Fabien explained it to me, so I think you are correct. One >specialtity is that Fruit counts all squares where the piece can go plus the >enemy pieces which are attacked. It is actually possible to give these two >concepts different weights but so far it does not seem to increase the strength. > >regards Joachim This is similiar to the way public movei already calculates mobility by the number of the legal moves and it has no concept of open files(mobility score for fruit can also be calculated based on the number of the legal moves of pieces when the only difference is that you need to know the number of moves of every piece). I thought that I may need to change it and to define mobility forward and mobility backward and I saw few cases when public movei suffered from the fact that it did not evaluate open files. Latest movei give static bonus for open files for rooks and the same panelty for closed file when open files are defined the same way as they are defined in fruit1.0 based on Fabian's post but I am also not sure if it increase the strength(it beated previous version in the nunn match but scored similiar to movei00_8_198 in Heinz tournament). There are also some other changes when I am not sure that they increase the strength. I wonder if fruit1.5 evaluates open files directly seperate from mobility. I did not find it in the evaluation but maybe I did not look well enough. Another question is if it evaluates knight outposts. One suggestion that may help fruit is to have some mobility table with the idea that very negative mobility is worse than what is suggested by the mobility score. I do it in movei. I do not consider it as something that is hard to find by yourself because it is similiar to the idea that king safety is not something linear but maybe other people do not use it. Maybe it is one of the reasons that movei is considered by some testers to have good mobility evaluation. My solution to the problem of endgame(very bad mobility may be not so bad is simply to divide the score by 2 or 4 based on the number of pieces but I think that the substraction idea in fruit may be better). Uri
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