Hi Marco.mcostalba wrote:Why it favors black and not white? What if position is flipped? It would favor white instead?Lyudmil Tsvetkov wrote: this is precisely the type of position for which the white king should receive some nice penalty, as the general pattern favours black very much, especially what concerns possible king attacks.
Once detected the closed position how can SF understand if it favors white or black?
I guess in closed position the most sane thing to do is to lower scale factors (i.e moving the evaluation toward a draw), independently from the side color.
You would feel the same way if I asked you does it make sense to use null move at all.
Well, the position favours black, and would favour white if flipped, for the reasons I already mentioned:
1. The e4 black chain pawn, the most advanced of the chain, is pointed toward Ke1, which is on the king side, but even better would be with Kg1,h1, etc. This e4 pawn is very close to the enemy king, and it is strong, it facilitates very much black king attack.
The most advanced white chain pawn, on the other hand, c5, is far away from the black king, so it does not help with the attack, and that is a major distinction.
2. The f2 white pawn is backward, a necessary condition for the closed trick to work. In order to defend well, especially with Kg1,h1, etc., this pawn needs to advance, and it is not very easy to do so with the enemy e4 chain pawn that restricts it. You see, if you play f2-f3 and e4 was not a chain pawn, you could just change pawns and e4 disappears. Now, because it is a chain pawn close to the enemy king, it reproduces itself automatically by capturing d5e4, and that means this is already a long-term factor, and black has more time to rely on this factor to launch a king-side attack.
Very well that you submitted a test, but I think it will not help in the particular position and with the particular detector. If you want to detect draws, as the test you submitted attempts, it better for me to scale when there are at least 6 blocked pawns on all the board, and not only in the center. 6 blocked pawns already pretty much favour draw result, and it is good to scale score in that case. Even more scaling when there are 7 blocked pawns, 8 blocked pawns might mean on many occasions an automatic draw.
So that, if you would like to detect draws in fortress positions, you need another detector: i.e. when there are at least 6 blocked pawns on all the board, scale down score.
The detector I asked about, 3 blocked pawns in the center + a backward pawn for the side with the king at which the most advanced chain pawn and the chain itself is pointed, is designed to handle rich middlegame KID-type positions, which already favour one of the sides. This detector type could be meaningful in terms of elo, as a lot of wins could come from that knowledge. This is standard-type KID knowledge.
So, if anyone asks my advice what to do about the KID, I would say the following easy rule:
white pawns on c3,d4,e5, black pawns on c4,d5,e6,f7, and black king on the king side - then give 20cps penalty or so to the black king
white pawns on d3,e4,f5, black pawns on d4,e5,f6,g7, and black king on the king side - then give penalty to the black king
this completed with the mirrored positions for black.
That is all, it should improve SF understanding of KID structures which is not optimal currently. That was basically the Joona Kiiski suggestion that passed in early January STC and scored positively in LTC. My idea is just to suggest a probably more refined approach.
So it would make sense to push a test along these lines with penalty for the kings with the above pawn structures, this should be aimed at solving the KID.
If you want to push a test that assesses draw possibilities, you need a detector with 6 blocked pawns overall. When the blocked pawns are at least 6, you can scale down the score.