17 Bxc5 Qc8 18 b4 Nd7 and black plays 19...Nb6 and then regains the pawn on c5
17 Rd1 Qc6 18 Nd2 and white plays Qe2 and Nc4 keeps his advantage. White is a pawn up.
How is this position 3+ in evaluation and 0 after taking a pawn in this position?
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Oct 11, 2023
0
#3
That's not my question. I am asking why the position is 3+ points. You are just listing engine lines and not explaining the evaluation.
@3
17 Rd1 wins for white, 17 Bxc5? draws.
The fundamental reason is that 17 Rd1 keeps a queen's side pawn majority that will later lead to a passed pawn and then to promotion to a queen unless black gives up a piece to stop that, hence +3.
17 Bxc5? spoils the queen's side pawn majority hence equality 0.
Oct 11, 2023
0
#5
Ok, thank you for explaining. I am not good with this pawn majority stuff.
The answer is that Black is stuck with a bad bishop.
LeftoverChessPieces wrote:
The obvious threat is a pin on move 17 for white if it takes on c5. But there is b4. Why can't that be played? Even if we see the trades favor black to a ~0 position, how is it 3+ if we refrain from taking the pawn. I can see the equalization after taking, but I don't see what the advantage is without taking. Here is the position.
It seems obvious that white has a good position and f4 is playable, either right away or after a little preperation, with quite a bit of pressure. Apart from the fact that white isn't winning a pawn in your line, white's position is deteriorated by it. At the moment, white's Q is nicely placed. Why spoil it?
I just had a look using the excuse for an engine they have on this site. Rd1 can't be right. The rook's on the right square where it is. The engine also likes a knight move just for development.
I would play an immediate f4. Despite the engine's evaluation, I think white attacks now, while black is not properly developed. I think f4 is stronger than the engine's evaluation.
LeftoverChessPieces wrote:
Ok, thank you for explaining. I am not good with this pawn majority stuff.
Seriously, you should not have accepted that explanation. Mostly because it is not true.
The truth is more complicated, like this:
In the original position, white is up a pawn, plus black's pawns are all weak, plus black's pieces are all bad (especially the bishop). Adding all these together give an advantage not +1, but +3.
On the other hand, why is the Bxc5 line worse? First of all, it does not really win a pawn. Black will pin the bishop, then win the pawn back (see comment #2). After that, white is still up a pawn, but black's pieces have come to life. The evaluation is not 0.0, obviously (I don't know where you got that from), but white's advantage is small, while in the other line it is not small.
Oct 12, 2023
0
#10
magipi wrote:
The evaluation is not 0.0, obviously (I don't know where you got that from), but white's advantage is small, while in the other line it is not small.
What number do you want to use?
Optimissed wrote:
I just had a look using the excuse for an engine they have on this site. Rd1 can't be right. The rook's on the right square where it is. The engine also likes a knight move just for development.
I would play an immediate f4. Despite the engine's evaluation, I think white attacks now, while black is not properly developed. I think f4 is stronger than the engine's evaluation.
I'm not sure how you can say the engine is wrong; I'd like to see you play a game vs it and win. The engine judges f4 as a bad move because it is entirely unconvinced there is actually an attack there; sure playing against a flawed person it might actually be better to play f4, as they will not know the best way to defend the attack, but the engine is assuming it's opponent is just as good as it; meaning it knows that there's no solid attack after f4.
Oct 12, 2023
0
#12
I believe the OP asks for an explanation that human brain can understand, using human chess theories. So here i am giving it a try:
The original position, black has two bad pawns: a isolated c pawn, and a stacked e pawn. What makes it worse is that those two pawns blocked its dark square bishop.
Meanwhile, white pawns are mostly light square, so its dark square bishop is more active.
If white takes the c pawn, black will be able to :
1) trades the isolated c pawn with a white b pawn. Now white pawns are no longer connected. Instead white has 2 isolated pawns, a pawn and c pawn. The c pawn is very vulnerable. If black attacks the c pawn i don't see how white can protect it. and
2) trades its inactive dark square bishop with white's active dark square bishop.
Both trades are bad for white.
@5
"I am not good with this pawn majority stuff"
++ Well it is simple. White is a pawn up. White can create a passed pawn, advance it and queen it. Black must give a piece to avoid that. Hence +3.
What people say about the good bishop Be3 and the bad bishop Bd6 is true, but does not explain the +3. White can win with the extra pawn, but not with the good bishop.
So the right plan is to prepare the creation and advance of a passed pawn, by first activating pieces: 1 Rd1, 2 Qe2 3 Nd2 4 Nc4.
1 Bxc5? does not win a pawn and makes it nearly impossible to advance a passed pawn for the win.
With the Rd1 line you get a passed pawn on the b-file which gets pushed all the way to b7,
all the pieces get traded off apart from the bishops so black has to put his bishop on b8 to stop the passed pawn until he can get his king to the other side.
White uses his Bishop to win the pawns on the other side of the board
The obvious threat is a pin on move 17 for white if it takes on c5. But there is b4. Why can't that be played? Even if we see the trades favor black to a ~0 position, how is it 3+ if we refrain from taking the pawn. I can see the equalization after taking, but I don't see what the advantage is without taking. Here is the position.