Author: Russell Reagan
Date: 09:47:49 04/30/02
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On April 30, 2002 at 11:51:29, JW de Kort wrote: >hi friends > >i am currently working on the improvement of my pawn evaluation. I wonder how to >define a weak pawn. I have studied the appropriate code in Crafty but it is not >completely clear to me. Is it correct to assume that a pawn cannot be weak if it >is not on a open file? > > >Thanks in advance > >Jan WIllem A weak pawn is basically a pawn that is going to cause you some kind of disadvantage. I'll go through the examples. An isolated pawn cannot be defended by your other pawns, so you must defend it with your pieces. So if you have to put your pieces to work defending that pawn, then your pieces aren't free to attack or defend other places on the board, and often your pieces get in each other's way, and you end up having to give up a piece or lose your isolated pawn. Once you lose the isolated pawn, not only are you down a pawn, but your pieces are out in the open because there are three open files now, and the enemy can attack that quite nicely. Isolated pawns aren't always bad though. I've seen master games where one player set a trap for his opponent by allowing himself to get an isolated pawn, and then the opponent followed the typical plan of piling up attackers on the isolated pawn, and it ended up being a trap for his opponent. I don't recall exactly how it worked, but the point is that isolated pawns are usually weak, but not always. Then you have doubled pawns. Doubled pawns aren't always bad either, but they are usually harder to guard and they usually get in the way of your pieces. This usually leads to your pieces being uncoordinated and they get in each other's way, and the same situation arises that you had in the isolated pawn situation where you either have to give up a pawn or a piece because you let your pieces get so uncoordinated and in each other's way. Doubled pawns can be an advantage sometimes, especially in the opening. If you have both doubled pawns attacking the center, that's usually a good thing, and often you can trade off one of the doubled pawns for one of the opponent's center pawns and you can end up with an advantage. So here again, it can be good sometimes, but usually it's a bad thing. Then we have backward pawns. Backwards pawns are just pawns that have fallen our of the pawn chain. In other words, they can't be protected by your other pawns, so you have to guard the pawn with your pieces instead (seeing a pattern yet?). Once again this leads to you having to defend the pawn with your pieces, and often what happens is that the pieces get in each other's way and your opponent sets up some tactics or forces some of your pieces to move away from defending the pawn, and the opponent can win the pawn. So basically there is a kind of pattern here. You have a pawn that for some reason needs the pieces to protect it instead of having other pawns protect it, and your pieces don't have a lot of options if they are tied down to guarding a pawn on a single square. Think about it, your knights and bishops pretty much have to stay put if they're guarding a square, and your rooks have a little bit of room, but they still can't move off the rank or file that they are guarding the pawn on, and your queen can move around a little and still guard the pawn, but do you really want to use your queen for something as simple as guarding a pawn? Basically guarding a pawn with your pieces isn't a good thing. It means your pieces can't really move, and if you have a pawn and a piece or two that can't really move, then those pieces get in the way of the rest of the pieces, and before you know it, half of your pieces are stuck without many options. So that's kind of a summary of why weak pawns are weak. I'm not sure how you would implement this into a program, but that's where you have to let yourself be creative and figure out how to program these kinds of things into your program. One "easy" method would be to say if a pawn can't be guarded by other pawns then it's "weak" because your pieces will have to guard it. That won't be true 100% of the time, but that is a good general rule that would take care of things most of the time. Russell
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