Author: Vasik Rajlich
Date: 12:17:41 12/03/04
Go up one level in this thread
On December 03, 2004 at 09:27:53, José Carlos wrote: >On December 03, 2004 at 07:26:24, Vasik Rajlich wrote: > >>On December 02, 2004 at 14:51:04, José Carlos wrote: >> >>> >>>>What is the definition of closed files? >>>>By movei's definition closed files are files that are not open and >>>>open files are files when there is no friendly pawn that prevent the rook to >>>>go forward(there may be pieces or pawns of the opponent that prevent it to go >>>>forward but if you remove all pieces except friendly pawns the rook can go to >>>>the 8th rank). >>>> >>>>By movei's definition the b file is an open file because there are no friendly >>>>pawns in that file. >>>> >>>>Movei has a bonus of 0.1 pawns for rook on open file and panelty of 0.1 for >>>>closed file and I am not sure if that bonus and panelty is productive. >>>> >>>>It was productive in the positions that I tested at the time that I implemented >>>>it but I did not play enough games and it is possible that the positions were >>>>misleading and in different positions I could get different results. >>>> >>>>Uri >>> >>> If there is an enemy pawn in an open line, and it's defended by another pawn, >>>that's not likely to be a useful place for a rook. >>> The definition to open line is a line without any pawn. >>> A closed line is a line with a friendly pawn. >>> A semi-open line is a line with no friendly pawn but opponent's pawn. >>> Those three should have IMO different bonus/malus. >>> It is also important to check if a rook in a line can eventually move into >>>enemy's position. For example, in the following position: >>>[D]r2qkbnr/p1pppppp/1b6/8/8/8/P1PPPPPP/1RBQKBNR w Kkq - 0 1 >>> The rook is not very useful in b1. Same for this position: >>>[D]r2qkbnr/p1bppppp/2b5/2p5/8/8/P1PPPPPP/1RBQKBNR w Kkq - 0 1 >>> >>> José C. >> >>Just one thing to add here: these positions are pretty much the worst-case >>scenarios for a totally open file, and they're nowhere near as bad as some of >>the bad half-open-file cases (as for example from Movei-Junior). If you're going >>to give automatic bonuses, it seems that the bonus for a completely open file >>should be quite a bit higher than for a half-open file. >> >>Vas > > The good thing for checking this kind of "false" open lines and give them a >small penalty compared to "true" open lines, is that the program has something >to do, some "plan". For example, in the first position above the program will >tend to disturb the bishop with the a or c pawn. In the second, the program will >try to exchange one of the bishops to get a square to move the rook to. The >penalty must be very small, of course. These plans make sense if there's nothing >important to do first. > > José C. True - that's the beauty of search. Vas
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