What is a backward pawn?

[Lyudmil Tsvetkov]

My take on this is that you are somewhat mixing terms.

A pawn that is defended by a pawn is not considered backward in any book I have (g6 in your first example as it is defended by h7). The fact that it can not safely advance is not so important when it is perfectly safe where it is. If you want to talk about it being immobile, that is a different issue.

the "unopposed" requirement stems from the rook, in the books I have read over the years. A pawn that is backward (can not be safely defended by a friendly pawn) is generally considered to be worse if it is (a) on a half-open file (no enemy pawn in front of it AND (b) the enemy has rooks to attack it.

IMHO, a pawn that is backward and unopposed is not any weaker or stronger than a backward pawn that is opposed, if there are no enemy rooks to contend with. Any backward pawn is weak, and inviting to enemy kings in the endgame. backward pawns on half-open files make inviting targets even in the middle game if you have rooks to attack on the file.

I've seen games decided by two types of backward pawns, repeatedly.

The first is the classic backward pawn on a half-open file, which is just as bad as an isolated pawn on a half-open file, when the enemy has rooks. Pile up on the pawn, tying up the opponent by making him defend, and either win the pawn outright, or switch to some other idea once he is tied down and not coordinated very well.

The second is a pawn that is backward, but the file is not half-open. If you have just one, you might manage to defend it with your king, depending on the position. If you have two, the enemy king can make you commit to saving one and then to eat the other pawn chain. Doesn't matter whether the file is half open or not.

[d]6k1/5p2/4p1p1/3p2P1/1p1P4/p7/P7/6K1 w - - 0 1

I tend to concur with Bob's definition. In the diagram above the e6 pawn is still defended, and thus not vulnerable to direct attack, so that's an argument against calling it backward.

However, since it cannot safely advance, there is an element of backwardness about it, and the square in front of it (e5) can serve as a good outpost for White pieces. These considerations should justify some sort of a penalty for such a pawn, but a lesser one that a fully backward [undefendable by a fellow pawn] pawn on an open file.

The Black b-pawn, even though backward, could be pushed in some cases creating a dangerous advanced passed pawn. It's not as clear whether a backward pawn that sits in the opponent's half of the board deserves any significant penalty.

CL

Crafty calls that a3 pawn a "hidden passed pawn". GM Dzhindi used to call this a protected passed pawn himself, because a3 is certainly passed here when you think about it and it is defended by b4. after b3 black ends up with a passed pawn for certain.

You really do not read this thread.

When you add pieces, there is no danger of a passed pawn.

[d][d]6k1/5p2/4p1p1/n2p2P1/1p1P4/p7/P7/2N3K1 w - - 0 1
One knight each side added; where is the danger of the hidden passed a3 pawn?
a3 is not an immediate danger, but b4 is certainly backward, like it or not, a2 stops both a3 and b4 pawns by blocking a3 and attacking the stop square of b4.

[Lyudmil Tsvetkov]

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/1P1Q1K2/4R2R w - - 0 1
If we add one more white pawn to the diagram on b2, already b5 will not be backward, neither will b2 itself, as it is 2 vs 2. So the condition that a backward pawn is necessarily not opposed is essential, I think.

[bob]

My take on this is that you are somewhat mixing terms.

A pawn that is defended by a pawn is not considered backward in any book I have (g6 in your first example as it is defended by h7). The fact that it can not safely advance is not so important when it is perfectly safe where it is. If you want to talk about it being immobile, that is a different issue.

the "unopposed" requirement stems from the rook, in the books I have read over the years. A pawn that is backward (can not be safely defended by a friendly pawn) is generally considered to be worse if it is (a) on a half-open file (no enemy pawn in front of it AND (b) the enemy has rooks to attack it.

IMHO, a pawn that is backward and unopposed is not any weaker or stronger than a backward pawn that is opposed, if there are no enemy rooks to contend with. Any backward pawn is weak, and inviting to enemy kings in the endgame. backward pawns on half-open files make inviting targets even in the middle game if you have rooks to attack on the file.

I've seen games decided by two types of backward pawns, repeatedly.

The first is the classic backward pawn on a half-open file, which is just as bad as an isolated pawn on a half-open file, when the enemy has rooks. Pile up on the pawn, tying up the opponent by making him defend, and either win the pawn outright, or switch to some other idea once he is tied down and not coordinated very well.

The second is a pawn that is backward, but the file is not half-open. If you have just one, you might manage to defend it with your king, depending on the position. If you have two, the enemy king can make you commit to saving one and then to eat the other pawn chain. Doesn't matter whether the file is half open or not.

[d]6k1/5p2/4p1p1/3p2P1/1p1P4/p7/P7/6K1 w - - 0 1

I tend to concur with Bob's definition. In the diagram above the e6 pawn is still defended, and thus not vulnerable to direct attack, so that's an argument against calling it backward.

However, since it cannot safely advance, there is an element of backwardness about it, and the square in front of it (e5) can serve as a good outpost for White pieces. These considerations should justify some sort of a penalty for such a pawn, but a lesser one that a fully backward [undefendable by a fellow pawn] pawn on an open file.

The Black b-pawn, even though backward, could be pushed in some cases creating a dangerous advanced passed pawn. It's not as clear whether a backward pawn that sits in the opponent's half of the board deserves any significant penalty.

CL

Carl, whether e6 is defended or not is another matter, completely unrelated to backwardness, i.e. underdevelopedness, inability to advance. Defended and undefended pawns already get their separate bonus/penalty points. We are taling here about the inherent inability of the e6 pawn to advance. That matters very much, pawns are there to advance, help in the attack, promote, etc. If your pawns do not advance to attack the enemy and promote, then it will be your opponent's pawns which will do that to win the game. So that a passive state of inability to advance should always be penalised, regardless of whether such pawns are defended or not. The defended/undefended bonus/penalty is just a small fraction of the penalty for a backward pawn unable to advance without being lost, so that backwardness is the much more important concept.

[d]6k1/5p2/4p1p1/n2p2P1/1p1P4/p7/P7/2N3K1 w - - 0 1
You see above that in the usual case with pieces present, b4 does not represent any real danger of supporting promotion, but is still unable to advance without being lost. So that it is still backward. Of course, a backward pawn on the 4th rank deserves a very small penalty, much less than a backward on the 5th. That is what we have been talking about, the introduction of a unified concept that works across ranks, i.e. a good practical eval term.

How practical and good are current backward definitions that mix backward with weak, isolated, overextended, undefended?

Again, I think the definition I specified, with some 30cps penalty for the 7th rank, 15cps for the 6th rank, 8cps for the 5th rank, and 4cps for the 4th rank, is a good, working definition, unified and applicable across ranks. When you apply a unified feature across ranks, chances are you will get the most out of it.

I ask myself again, who is to blame when modern top engines fully misunderstand backward pawns? And if they badly misplay such pawns, is it possible that the definitions used for backward are good and working ones? Why should you mix backward with isolated, overextended (meaning vertically isolated) and undefended? You already have definitions and penalties for isolated and undefended. No, the only conclusion I draw from that is that currently a complete chaos reigns in the computer chess world as to what actually a backward pawn is. And that is the main reason why engines play so weak with backward pawns.

I wonder who will be the first author who will drastically change his approach and definitions of backward pawns to easily gain (after tuning of course) another 50 elo strength?

I don't think the term "backward" is related to mobility directly. A backward pawn is one that can not be defended, and which is weak where it stands offering the opponent a clear target. There is, to me, a difference between being immobile, and being backward. Immobile is certainly a problem, but not nearly the same as being backward AND immobile.

See this: http://talkchess.com/forum/viewtopic.ph ... 44&t=52300

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/3Q1K2/4R2R w - - 0 1
Is not b5 a backward pawn?

By the definition I got from Kmoch many years ago, no. It is not attackable as it stands. I can pile up every piece I have on that pawn and all I am threatening to do is sacrifice material. The pawn is definitely immobile, but that can be temporary if I can support the advance square enough times. The thing that makes an isolated pawn weak (it is not and can't be defended by a friendly pawn, which means when it is attacked it has to be defended by a piece) is the same thing that makes a backward pawn weak. Each enemy attack requires a piece to avoid losing the pawn.

Backward pawns generally fall in a discussion about "weak pawns." I'm not sure that fits the b5 pawn above for the reasons I gave. Yes, the pawn should receive a penalty due to lack of mobility, or else the other pawns that are free to move should get a bonus for being able to advance, but calling it weak? What if the most advanced pawn in a chain can't move. Is it really weak? Black pawn on d5 in your position, for example.

There's nothing wrong with disagreeing on this. I am simply giving you my "take" on the topic. In trying to recognize/valuate weaknesses, whether those weaknesses are specific pawns or just weak squares, I am trying to recognize things that will require some action on my part, such as moving a piece to defend the weakness. If the "weakness" doesn't require any attention, then it is not much of a weakness since it doesn't divert my attention from something else.

[bob]

My take on this is that you are somewhat mixing terms.

A pawn that is defended by a pawn is not considered backward in any book I have (g6 in your first example as it is defended by h7). The fact that it can not safely advance is not so important when it is perfectly safe where it is. If you want to talk about it being immobile, that is a different issue.

the "unopposed" requirement stems from the rook, in the books I have read over the years. A pawn that is backward (can not be safely defended by a friendly pawn) is generally considered to be worse if it is (a) on a half-open file (no enemy pawn in front of it AND (b) the enemy has rooks to attack it.

IMHO, a pawn that is backward and unopposed is not any weaker or stronger than a backward pawn that is opposed, if there are no enemy rooks to contend with. Any backward pawn is weak, and inviting to enemy kings in the endgame. backward pawns on half-open files make inviting targets even in the middle game if you have rooks to attack on the file.

I've seen games decided by two types of backward pawns, repeatedly.

The first is the classic backward pawn on a half-open file, which is just as bad as an isolated pawn on a half-open file, when the enemy has rooks. Pile up on the pawn, tying up the opponent by making him defend, and either win the pawn outright, or switch to some other idea once he is tied down and not coordinated very well.

The second is a pawn that is backward, but the file is not half-open. If you have just one, you might manage to defend it with your king, depending on the position. If you have two, the enemy king can make you commit to saving one and then to eat the other pawn chain. Doesn't matter whether the file is half open or not.

[d]6k1/5p2/4p1p1/3p2P1/1p1P4/p7/P7/6K1 w - - 0 1

I tend to concur with Bob's definition. In the diagram above the e6 pawn is still defended, and thus not vulnerable to direct attack, so that's an argument against calling it backward.

However, since it cannot safely advance, there is an element of backwardness about it, and the square in front of it (e5) can serve as a good outpost for White pieces. These considerations should justify some sort of a penalty for such a pawn, but a lesser one that a fully backward [undefendable by a fellow pawn] pawn on an open file.

The Black b-pawn, even though backward, could be pushed in some cases creating a dangerous advanced passed pawn. It's not as clear whether a backward pawn that sits in the opponent's half of the board deserves any significant penalty.

CL

Crafty calls that a3 pawn a "hidden passed pawn". GM Dzhindi used to call this a protected passed pawn himself, because a3 is certainly passed here when you think about it and it is defended by b4. after b3 black ends up with a passed pawn for certain.

You really do not read this thread.

When you add pieces, there is no danger of a passed pawn.

[d][d]6k1/5p2/4p1p1/n2p2P1/1p1P4/p7/P7/2N3K1 w - - 0 1
One knight each side added; where is the danger of the hidden passed a3 pawn?
a3 is not an immediate danger, but b4 is certainly backward, like it or not, a2 stops both a3 and b4 pawns by blocking a3 and attacking the stop square of b4.

Very simple. White has to avoid any move that lets me force the exchange of knights. Because allowing such is an instant loss. Unless white chooses to brink his king over to the a-file area, which ties it down and restricts white's ability to defend elsewhere.

Adding the knights does NOT eliminate the advantage of a3-b4, it just makes it harder to use that advantage. In this case, as black I would try to get the knight to c3 and take on a2. White knight will have great trouble with the a/b pawns after that

[arjuntemurnikar]

See this: http://talkchess.com/forum/viewtopic.ph ... 44&t=52300

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/3Q1K2/4R2R w - - 0 1
Is not b5 a backward pawn?

This a very instructive position about backward pawns, and no doubt very controversial.

Lyudmil, do you also then consider e3 and g6 pawns as backward? They both have squares in front of them that are defended once but attacked twice -- making them practically "immobile".

[BeyondCritics]

I think both chess engines and humans compute and evaluate in precisely the same way

This is just polemic, not more.

Humans are stronger where they have more knowledge, and engines where their knowledge is superior to human knowledge.

Knowledge of engines superior to humans??? Are you kidding??? If they have access to their databases, then i agree with you.

A good example is king attack. Engines are on average, at least the top, much better than humans in attacking the enemy king with pieces. Why? Because they have more knowledge than humans about attacking; while humans just follow general patterns, engines calculate the attacking weight for each piece and each specific square. This is what I call knowledge, humans do not have this knowledge. Engines are very good on this because they started very early elaborating on king attack. This is an area they worked hard on.

If i understand you correctly, you claim that the level 0 evaluation of stockfish is superior to that of say Kasparovs judgement.
I can't take that seriously either.

Same goes true for mobility: engines are better what concerns overall piece mobility, as they calculate precise numbers there, something humans can not do.

No please. If that would be true, everyone would do that in correspondence chess. In fact nobody does such a thing, it has nothing to do with chess. It is just a cheap, noisy statistic.

But humans are better in assessing the mobility for each particular piece. Why so? Simply because, as I understand, most engines do not give individual bonus for each piece, which I think is important. Because this lack of knowledge, you see engines like Komodo, Stockfish, Houdini in TCEC playing sometimes ugly games, losing because of extremely low mobility for a particular piece.

I agree, human are currently better in recognizing e.g. trapped pieces. The examples you have given elsewhere seems to be meaningful.

Same is true of pawn features like passers and isolated pawns: engines treat them relatively well, as the definitions and knowledge they have about those features are more or less precise and sufficient. However, when you come to backward pawns, here already engines are very bad and know almost nothing, I think in the first place because their definitions of backward pawns are, if not completely wrong, then very much imprecise.

Disagree, but i am tired now.

An example: what you mention about backward pawns being weak, undefended pawns, is simply not true. Backward pawns are not about being weak or undefended, but about the inability to advance.

OK, agreed. It was not my intent to claim that a backward pawn must always be undefended, this is an oversight. A backward pawn _could_ be "weak".

Below a position from TCEC, I am not certain this is exactly the same position, but an approximation. It is from round 26 of current stage 4, in the game Komodo-SF. I watched the game on the site, but when I now try to download games, I do not have access at the moment. So it is an approximation, but the pattern is the same.

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/3Q1K2/4R2R w - - 0 1

Komodo thinks here white is 40cps worse, SF even sees 60cps black advantage. However, the position is equal. Both engines fail to take something into consideration. I guess this is the b5 black pawn, which is objectively a backward pawn, but I am almost certain none of the engines thinks so.

Don't agree. Black is clearly preferred here: White has a bad bishop, weak pawn on a5, isolated pawn on h4. White is very passive, pieces are uncoordinated. Whites king has no shelter, this can tell if the positions opens. White can therefore only sit and wait. Black is fully active, has the superior knight and two meaningful breakthrough attempts: b4 and even g5 later. Maybe white can hold this.

Do you agree b5 is a backward pawn due a nice penalty?
Well, b5 is a chain/connected pawn, so it is defended/not weak, but in spite of this it is backward because of its inability to advance. One white pawn, c3, stops 2 black pawns at the same time, it blocks c4 and attacks the stop square of the b5 pawn. As b5 is not opposed, it is simply a backward pawn. Checking for friendly pawns that could support b5 from behind on adjacent files: well, there is such a pawn, a6, but it is blocked by white a5, so realistically it can never support b5 in its advance to the b4 square.

Agreed as a chess player. b5 is backward.
And again agreed, the engine evaluation of pawns leaves very much to be desired. This is not only about backwards pawn.
But let me ask you one thing: Do you really believe, that after 50 years of intense research in chess programming of the brightest minds, they still don't get their absolute basics right and that you lyudmil are the only one to rescue them?
Common sense dictates: no.
Their evaluation is incomplete, because they have a reason for that.
I have attempted to explain that mildly, but this was a complete failure i see.

[Lyudmil Tsvetkov]

See this: http://talkchess.com/forum/viewtopic.ph ... 44&t=52300

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/3Q1K2/4R2R w - - 0 1
Is not b5 a backward pawn?

This a very instructive position about backward pawns, and no doubt very controversial.

Lyudmil, do you also then consider e3 and g6 pawns as backward? They both have squares in front of them that are defended once but attacked twice -- making them practically "immobile".

Perfect. I would.

But I am afraid Marco will kill me, if I suggest that.

That was the reason I said backward pawns are actually the most frequent pawns, way above passers and other pawns, if you spread the definition wide enough. e3 an g6 perfectly match an extended definition of backward pawns.

[Lyudmil Tsvetkov]

My take on this is that you are somewhat mixing terms.

A pawn that is defended by a pawn is not considered backward in any book I have (g6 in your first example as it is defended by h7). The fact that it can not safely advance is not so important when it is perfectly safe where it is. If you want to talk about it being immobile, that is a different issue.

the "unopposed" requirement stems from the rook, in the books I have read over the years. A pawn that is backward (can not be safely defended by a friendly pawn) is generally considered to be worse if it is (a) on a half-open file (no enemy pawn in front of it AND (b) the enemy has rooks to attack it.

IMHO, a pawn that is backward and unopposed is not any weaker or stronger than a backward pawn that is opposed, if there are no enemy rooks to contend with. Any backward pawn is weak, and inviting to enemy kings in the endgame. backward pawns on half-open files make inviting targets even in the middle game if you have rooks to attack on the file.

I've seen games decided by two types of backward pawns, repeatedly.

The first is the classic backward pawn on a half-open file, which is just as bad as an isolated pawn on a half-open file, when the enemy has rooks. Pile up on the pawn, tying up the opponent by making him defend, and either win the pawn outright, or switch to some other idea once he is tied down and not coordinated very well.

The second is a pawn that is backward, but the file is not half-open. If you have just one, you might manage to defend it with your king, depending on the position. If you have two, the enemy king can make you commit to saving one and then to eat the other pawn chain. Doesn't matter whether the file is half open or not.

[d]6k1/5p2/4p1p1/3p2P1/1p1P4/p7/P7/6K1 w - - 0 1

I tend to concur with Bob's definition. In the diagram above the e6 pawn is still defended, and thus not vulnerable to direct attack, so that's an argument against calling it backward.

However, since it cannot safely advance, there is an element of backwardness about it, and the square in front of it (e5) can serve as a good outpost for White pieces. These considerations should justify some sort of a penalty for such a pawn, but a lesser one that a fully backward [undefendable by a fellow pawn] pawn on an open file.

The Black b-pawn, even though backward, could be pushed in some cases creating a dangerous advanced passed pawn. It's not as clear whether a backward pawn that sits in the opponent's half of the board deserves any significant penalty.

CL

Crafty calls that a3 pawn a "hidden passed pawn". GM Dzhindi used to call this a protected passed pawn himself, because a3 is certainly passed here when you think about it and it is defended by b4. after b3 black ends up with a passed pawn for certain.

You really do not read this thread.

When you add pieces, there is no danger of a passed pawn.

[d][d]6k1/5p2/4p1p1/n2p2P1/1p1P4/p7/P7/2N3K1 w - - 0 1
One knight each side added; where is the danger of the hidden passed a3 pawn?
a3 is not an immediate danger, but b4 is certainly backward, like it or not, a2 stops both a3 and b4 pawns by blocking a3 and attacking the stop square of b4.

Very simple. White has to avoid any move that lets me force the exchange of knights. Because allowing such is an instant loss. Unless white chooses to brink his king over to the a-file area, which ties it down and restricts white's ability to defend elsewhere.

Adding the knights does NOT eliminate the advantage of a3-b4, it just makes it harder to use that advantage. In this case, as black I would try to get the knight to c3 and take on a2. White knight will have great trouble with the a/b pawns after that

We are talking here about a static feature, and the static feature is that one white pawn, a2, holds 2 black pawns, a3 and b4, simultaneously.

[arjuntemurnikar]

See this: http://talkchess.com/forum/viewtopic.ph ... 44&t=52300

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/3Q1K2/4R2R w - - 0 1
Is not b5 a backward pawn?

This a very instructive position about backward pawns, and no doubt very controversial.

Lyudmil, do you also then consider e3 and g6 pawns as backward? They both have squares in front of them that are defended once but attacked twice -- making them practically "immobile".

Perfect. I would.

But I am afraid Marco will kill me, if I suggest that.

That was the reason I said backward pawns are actually the most frequent pawns, way above passers and other pawns, if you spread the definition wide enough. e3 an g6 perfectly match an extended definition of backward pawns.

I think you raised some interesting points. Whether your definition is strictly correct "by the book" or not, I will not dispute, but I think it makes perfect sense to differentiate between a backward pawn which can be attacked and a backward pawn which is just immobile. Both deserve penalties in different amounts.

Probably, I will do it this way:

-- Define a backward pawn as a pawn that cannot advance "immobile" (based on Lyudmil's definition). Give a small penalty for it (based on rank and file).
-- Further define a weak pawn as any pawn that can be attacked but cannot be dissolved or protected (i.e. Backward pawns on semi-open file, Isolated pawns, overextended pawns, pawns at the base of a chain that is blocked, etc.). Give an additional penalty for such a pawn (based on rank and file)

The benefit here is that we have very clear and strict definitions for static pawn structures and clear bonuses/penalties for them. But, we additionally consider and award bonuses/penalties for dynamic features (can be attacked/can be defended) and we separate them out, just like we do for the threat evaluation of pieces.

I think this is a more elegant approach.

Regards,
Arjun

[Lyudmil Tsvetkov]

I think both chess engines and humans compute and evaluate in precisely the same way

This is just polemic, not more.

Humans are stronger where they have more knowledge, and engines where their knowledge is superior to human knowledge.

Knowledge of engines superior to humans??? Are you kidding??? If they have access to their databases, then i agree with you.

A good example is king attack. Engines are on average, at least the top, much better than humans in attacking the enemy king with pieces. Why? Because they have more knowledge than humans about attacking; while humans just follow general patterns, engines calculate the attacking weight for each piece and each specific square. This is what I call knowledge, humans do not have this knowledge. Engines are very good on this because they started very early elaborating on king attack. This is an area they worked hard on.

If i understand you correctly, you claim that the level 0 evaluation of stockfish is superior to that of say Kasparovs judgement.
I can't take that seriously either.

Same goes true for mobility: engines are better what concerns overall piece mobility, as they calculate precise numbers there, something humans can not do.

No please. If that would be true, everyone would do that in correspondence chess. In fact nobody does such a thing, it has nothing to do with chess. It is just a cheap, noisy statistic.

But humans are better in assessing the mobility for each particular piece. Why so? Simply because, as I understand, most engines do not give individual bonus for each piece, which I think is important. Because this lack of knowledge, you see engines like Komodo, Stockfish, Houdini in TCEC playing sometimes ugly games, losing because of extremely low mobility for a particular piece.

I agree, human are currently better in recognizing e.g. trapped pieces. The examples you have given elsewhere seems to be meaningful.

Same is true of pawn features like passers and isolated pawns: engines treat them relatively well, as the definitions and knowledge they have about those features are more or less precise and sufficient. However, when you come to backward pawns, here already engines are very bad and know almost nothing, I think in the first place because their definitions of backward pawns are, if not completely wrong, then very much imprecise.

Disagree, but i am tired now.

An example: what you mention about backward pawns being weak, undefended pawns, is simply not true. Backward pawns are not about being weak or undefended, but about the inability to advance.

OK, agreed. It was not my intent to claim that a backward pawn must always be undefended, this is an oversight. A backward pawn _could_ be "weak".

Below a position from TCEC, I am not certain this is exactly the same position, but an approximation. It is from round 26 of current stage 4, in the game Komodo-SF. I watched the game on the site, but when I now try to download games, I do not have access at the moment. So it is an approximation, but the pattern is the same.

[d]4r3/3q3k/pBn1r1pp/Pp1p1p2/2pP1P1P/2P1PP2/3Q1K2/4R2R w - - 0 1

Komodo thinks here white is 40cps worse, SF even sees 60cps black advantage. However, the position is equal. Both engines fail to take something into consideration. I guess this is the b5 black pawn, which is objectively a backward pawn, but I am almost certain none of the engines thinks so.

Don't agree. Black is clearly preferred here: White has a bad bishop, weak pawn on a5, isolated pawn on h4. White is very passive, pieces are uncoordinated. Whites king has no shelter, this can tell if the positions opens. White can therefore only sit and wait. Black is fully active, has the superior knight and two meaningful breakthrough attempts: b4 and even g5 later. Maybe white can hold this.

Do you agree b5 is a backward pawn due a nice penalty?
Well, b5 is a chain/connected pawn, so it is defended/not weak, but in spite of this it is backward because of its inability to advance. One white pawn, c3, stops 2 black pawns at the same time, it blocks c4 and attacks the stop square of the b5 pawn. As b5 is not opposed, it is simply a backward pawn. Checking for friendly pawns that could support b5 from behind on adjacent files: well, there is such a pawn, a6, but it is blocked by white a5, so realistically it can never support b5 in its advance to the b4 square.

Agreed as a chess player. b5 is backward.
And again agreed, the engine evaluation of pawns leaves very much to be desired. This is not only about backwards pawn.
But let me ask you one thing: Do you really believe, that after 50 years of intense research in chess programming of the brightest minds, they still don't get their absolute basics right and that you lyudmil are the only one to rescue them?
Common sense dictates: no.
Their evaluation is incomplete, because they have a reason for that.
I have attempted to explain that mildly, but this was a complete failure i see.

50 years of intense research brought you a culmination that ends somewhere with Fritz. The last 10 years brought you Rybka. The last 5 years brought you Houdini. And the very last year brought you 2 other engines the level of Houdini and stronger. I will not be talking of the last months and the days ahead.

I do not see what you do not understand: engines play better king attacks, even than Kasparov, because Kasparov sees only general patterns, and engines count specific squares and weight pieces. Piece king attack is actually one of the most developed engine eval functions. That is what I call knowledge.