Even crazier

[syzygy]

Some very small example of the validity of apex pawns.

It seems both positions are drawn, so they don't seem to be an example of the validity of the concept. Your explanations seem to be a rewording of the definition of the term.

I don't mean to say that the concept has no value, but I do have the impression that you base your position intuitively on its definition. To really be sure that the concept adds value to current pawn evaluation terms used by top engines one would need to run many many tests. In my view "just look, it's obvious" does not work here.

[Lyudmil Tsvetkov]

Some very small example of the validity of apex pawns.

It seems both positions are drawn, so they don't seem to be an example of the validity of the concept. Your explanations seem to be a rewording of the definition of the term.

I don't mean to say that the concept has no value, but I do have the impression that you base your position intuitively on its definition. To really be sure that the concept adds value to current pawn evaluation terms used by top engines one would need to run many many tests.

Those are not specific positions, but simple illustrations, as in a more complex position you could be distracted by other details and not pay sufficient attention to the term discussed.
Really, do not you see that d5 in the first diagram is both very solid, and the structure as a whole very flexible, with one of the supporting pawns, e6 being able to advance easier than usual?

[syzygy]

Really, do not you see that d5 in the first diagram is both very solid, and the structure as a whole very flexible, with one of the supporting pawns, e6 being able to advance easier than usual?

But I do not need to see the diagram for that. By its very defintion an "apex pawn" has exactly the flexibility that you describe (unless I have misunderstood you).

The real question is whether awarding points to this flexibility gains Elo. Only if it does, the concept is "valid". That it does might be intuitively obvious to you, but this is not how top engines make progress nowadays.

[bob]

Two things.

1. Why try to invent a NEW pawn vocabulary? There are several good books on pawn structure. Kmoch comes to mind.

2. I don't like terms like "semi-backward." Why not just do as most upper-level players do and consider weak pawns. A backward pawn is weak. An isolated pawn is weak. An artificially isolated pawn is weak. Kmoch defines all of those. Ditto for majority, crippled majority, mobile majority, immobile majority, etc...

But these new terms are not going to catch on very well since there is already a lot of pawn structure analysis in GM books...

Mr. Hyatt, I respect you very much for your enormous contribution to computer chess, but, what would you suggest instead? Stick to the notions people invented 30-50-100 years ago and not progress any more, simply because we regard those doctrines as a dogma?

Do you really suggest that a scientific mind doing research some 100 years ago would really surpass persons that would inquire into interesting aspects of knowledge that probably exists, but is still unveiled? It would be really funny if it is like that. Actually, most branches of science and even art have already attained levels where there are very few substantial things to do, but, fortunately, computer chess is not one of those.

Do you realize the enormous progress being made in computer chess every year, including in terms of elo increase to the point where many programs already surpass the best humans? How much of this progress do you think is due to implementing eval terms in general, and, if you want to make a distinction, in applying existing and tinkering with new terms, previously unused? I guess eval would be responsible for 1/3 of all progress, including search and hardware. That is not negligeable.

I myself do not have any ambitions at all, I would be glad to help a bit some engines, if possible, as engines, including Crafty (thanks for this software!), have helped me quite a lot in my development. But is not it evident that some eval terms are really outdated? You can not do a 21-st century engine with concepts from the middle of the 20th century. Could you tell me what auothors of renown have suggested pawn concepts like backward-fated, unopposed, apex pawns, proximity of peak pawns to the enemy king, etc.? Do you think they are not valid concepts? Do they have to be suggested by Hans Kmoch in a paper edition to be valid?

I would suggest to do the following: try measuring the impact of, say, apex pawns, in Crafty, very easy to do, and see what happens. I suppose, if correctly implemented, with no redundancies, you will see some elo increase in Crafty, it might be 10 elo, but will be there. Why reject the existence of concepts that are useful?

Best, Lyudmil

Sorry, but nothing in your "new terms" is new. Read some good books on pawn structure, and you will see that you have not identified anything new at all...

Most authors I have read discuss your concepts. The "apex" is a part of a common attacking theme. Which is often modified by the direction of the pawns. For example, white pawns at d3,e4,f5 are in a chain pointing toward the enemy king, helping an attack, while black pawns at f6, e5, d4 also form a chain, but it points in the wrong direction.

As I said, using new terms for existing ideas doesn't help at all...

[Lyudmil Tsvetkov]

Sorry, but I don't get it. What can Black do here?

[d] 6k1/p6p/1p2p1pP/3pPpP1/2pP1P2/2P5/PP6/6K1 w - -

Black has no majority so can't create a passer, if I am not mistaken.

--Jon

Again, Jon, this was just an illustration of the principle, and not a position to evaluate properly if drawn or won.

I am posting here a position I posted back in January under the thread 'The space advantage that was non-existent'.

[d][d]r2q1rk1/1b1nbppp/4p3/3pP3/p1pP4/PpP2N1P/1P3PP1/R1BQRNK1 b 0 1

Engines evaluated this position in favour of black (and I think even the top still do), however, the position is favourable to white. The point is again, that all the space advantage for black, as well as good mobility on the queen side come to nothing, as the queen side is closed, you can neither open files, nor attack there. On the other hand, the only white pawn gaining space on the king side, e5, does a lot more and determines that the position favours white, as the king side is not fully closed, and under such circumstances the player who has space advantage on the side that is not fully closed will enjoy an overall advantage. Having space advantage in terms of pawns, but also minors as a rule supposes that the player having it will be able to attack, open files and develop further initiative. White can gradually increase its pressure on the king side, while black can not do the same on the queen, therefore its assets there come to nothing. If even one file on the quuen side had been open, that would already be another thing, but this is not the case.

Of course, this is just a random position. You can tweak it at will so that white will be even better on the king side, supposing an even easier intiative and win, but the majority of engines would still consider black as better. There should be something wrong with that, do not you think, something that is evaluated wrongly?

[syzygy]

The real question is whether awarding points to this flexibility gains Elo. Only if it does, the concept is "valid". That it does might be intuitively obvious to you, but this is not how top engines make progress nowadays.

And I should add that before trying this out, it must be determined whether the concept is not already implicit in other pawn evaluation terms. If it is, a new term would merely slow down parameter tuning by adding a redundant parameter.

[Lyudmil Tsvetkov]

Here just a small example of the validity of blocking with minors enemy passers.

[d]8/6kb/p3n1p1/Pp1nPp2/1PpPp2p/2P4P/3B2P1/2R1R1K1 b 0 1
This is a position I posted earlier in the 'Total mess thread' from February. As Terry Donahue has demonstrated in a superb way with Houdini 1.5, Houdini initially evaluates the position as 1.5 pawns better for white, but, when confronted with a shoot-out at longer time control, Houdini wins the position with black convincingly. How can that happen?

Actually, the position very strongly favours black, but how many engines would think so? I posted it again to illustrate the importance of piece blocking of enemy passers. This factor is real, and very real indeed. The excellent black knights on d5 and e6 perfectly block the white connected d4 and e5 passers, so those do basically nothing there: blocking with minors, especially the knight, is tantamount to depriving the enemy passers of their functionality. At the same time, black is soon going to form 2 connected passers, that are impossible to block, and consequently to stop. That makes an enormous difference, and decides the game. You do not need passers that can not advance.

Of course, there are other factors that would favour black to equalise and lead in the score: the unopposed pawn on f5 will help in creating another black passer (so why dismiss unopposed?); the white g2 backward pawn that might even become backward-fated; fully closed queen side, where white can do nothing, although having considerable advantage, versus the still open king side, where already black has superiority in space (2 pawns on e4 and h4 against one white on e5), this will suppose adding another 50cps to the black score, are only black has realistic chances to develop initiative and attack on the king side, where it prevails in space; the opposite square bishops also favour black, as they would increase here the invulnerability of the black passers (the black bishop can support the advance of the own passers on squares where the white bishop lacks control), etc.

When you add 60cps for blocking, another 50 and another 50, it is almost equal, but, truely, how many engines would think so, even after seraching some 30 moves ahead? This means that there are some real positional factors, subtler evaluation terms that can not simply be discarded. That they are not in wide use, or ignored generally, does not mean that they do not exist.

[Lyudmil Tsvetkov]

Sorry, but I don't get it. What can Black do here?

[d] 6k1/p6p/1p2p1pP/3pPpP1/2pP1P2/2P5/PP6/6K1 w - -

Black has no majority so can't create a passer, if I am not mistaken.

--Jon

Here, Jon, this is just for you. (btw., thanks for starting the discussion)

[d][d]8/6kb/p3n1p1/Pp1nPp2/1PpPp2p/2P4P/3B2P1/2R1R1K1 b 0 1
This is a specific position. The queen side is fully closed, black enjoys superiorirty in space on the king side (2 pawns on e4 and h4 versus one white on e5), therefore black should have overall advantage, or at least add a substantial bonus to its score.

How does Arasan evaluate this position? If not winning for black, does it at least see that the game is at least a draw, because only black is able to attack on one of the sides, and white can not budge even on the king side? (btw., as already shown in another thread, black should be winning here)

[Tord Romstad]

[d]6k1/p7/1p2p1p1/3pPp1p/2pP3P/2P1P1P1/PP6/6K1 w - - 0 1
Now, on the above position, g3 is still backward-fated, but g6 already is not, and you can not call the king side fully closed. There is a substantial difference. Could you possibly say that g6 in this diagram and g6 in the former one are one and the same pawn? This is ludicrous. So that, for me, backward-fated pawns have their right of existence, actually they are one of the most positional elements in chess, if chess programs are reluctant in general or unable to implement them, that is another question.

This reminds me of an evaluation term I once had, which I called "pawn structure mobility". What I did was to give every pawn on the board a bonus measuring its ability to move without getting lost or creating weaknesses. I don't remember the exact numbers I used, but the general idea, applied to the above position, would be something like this:

• The black pawns on a7 and b6 would get a significant bonus, because they are able to move freely without creating any backward, isolated or doubled pawns or important weak squares in their own camp.
• The black pawn on g6 would get a somewhat smaller bonus. If supported by a friendly piece, it can safely advance, but only at the cost of accepting an isolated pawn on h5.
• No other black pawns have any safe moves, they therefore don't get any bonus
• The white pawn on a2 only gets a small bonus, because moving it means weakening the square b3, which is attacked by a black pawn, and would render the b2 pawn locked in place.
• The white pawn on b2 also gets a small bonus, because moving it would give white (after b3 cxb3 axb3 b5) a backward pawn on c3.
• No other white pawns get bonuses, because they're all immobile, even with the support of friendly pieces.

This may seem expensive to compute (it even included a simple pawn-move-only search, as illustrated in the discussion of the white b2 pawn), but the nice thing about evaluation terms which *only* consider pawn structure is that you don't have to compute them very often. Even though the number of positions encountered during the search is astronomical, the number of distinct pawn structures are much smaller. The program remembers the pawn structures it has seen before, and only needs to perform the expensive pawn structure evaluation on the rare occasions when it encounters a previously unseen structure. This makes very complicated pawn structure evaluation terms like this one attractive to investigate. The programmers among you already knew all of this, of course, but I thought it would be interesting and useful for Lyudmil to learn.

Unfortunately, as is so often the case with complicated evaluation terms, I was never able to make it work well in practice. The program played some impressive-looking positional games from time to time and looked more intelligent, but the test results were still disappointing. Of course this doesn't mean that the idea is unworkable; it's quite possible that I was just too stupid and/or didn't work hard enough to make it work.

[jdart]

[d] 8/6kb/p3n1p1/Pp1nPp2/1PpPp2p/2P4P/3B2P1/2R1R1K1 b - - 0 1

White pawn score:
general = 0
midgame = 70
endgame = 91
blend = 91
Black pawn score:
general = 0
midgame = 54
endgame = 72
blend = 70

White gets a bonus for the passer (diminished because it is blocked by piece). Black has a majority here (unlike the other position I commented on) so gets a bonus for a potential passer. Overall White gets a little higher pawn score. Maybe wrongly.

Overall the position is scored as better for White because White has the two Rooks vs two minors.

--Jon