pointy chains redux (part 1)

[carldaman]

I'd like to go over the pointy chains issue again, this time attempting to break it down into finer details, which will hopefully assist others in their understanding, and (why not?) perhaps clear the path for improved coding implementations down the line.

This is not aimed at any particular engine or programmer, but an open-ended discussion that others should chime into with further on-topic comments or observations.

Firstly, I'd like to start off with a basic diagram illustrating a pointy chain that's directed at the enemy Kingside. (By the last statement, I mean that the Black King is situated on the short side of the board relative to the White pawn chain, namely on the g or h file) Let's not assume that these are the only pieces present on the board - indeed, if that were the case, there would hardly be any advantage conferred by the pointy chain.

[D]6k1/6pp/5p2/4pP2/3pP3/3P2P1/7P/6K1 b - - 0 1

The above position was arrived at after White's f4-f5, thus favorably 'extending the pawn chain'. Assuming sufficient material is on the board (i.e. especially the Queen and a bunch of other pieces - but more on this later), it is my contention that the d3-e4-f5 White chain is not only superior to the (longer) Black chain (g7-f6-e5-d4), but actually should give White a clear advantage due to far better Kingside attacking chances. The same considerations would hold true if the position was horizontally mirrored, and Black had the pointy chain directed at the White Kingside, as in the King's Indian proper. Also, I should quickly mention that the offensive pointy chain should contain at least 3 chain pawns, since a 2-pawn chain is much easier to undermine and would confuse the issue.

There's one more essential element present in the set-up in the above diagram that helps tip the balance in favor of the pointy chain directed at the Kingside, which I have not mentioned yet. [Without this element, the the position would likely be up for grabs, and the correct evaluation would probably depend on a myriad of other factors, rendering the whole pointy chain idea far less effective.] I invite the reader to take a good look at the position and try to determine what it might be.

OK, let's now compare the previous diagram with this one:


[D]6k1/6pp/5p2/2p2P2/3pP3/3P2P1/7P/6K1 b - - 0 1

We still have a pointy chain aimed at the Kingside, following the f4-f5 advance, but something is seriously amiss. There is no longer a black pawn on e5, and this should throw White's set-up for a loop. Again, it's my contention that that the pointy chain is no longer so favorable, as Black can use the open square on e5 in a number of ways to come up with effective counterplay.

So, it seems that our pointy chain concept really hinges on the presence of this pawn on e5. Here I would like to define a new term to aid us in our understanding - I'd like to call such a pawn as the one on e5 a congestion point, and it can be a favorable or unfavorable feature of the position depending on which way the chains are pointing, relative to the opposing Kingside.

While at it, let's come up with a better term for the foremost pawn at the tip of our pointy chain - I'd like to call it the spearhead. This will help us to better define the congestion point as the pawn directly in front of the chain pawn that is defending the spearhead. Its presence next to the spearhead is essential to the effectiveness of pointy chains in general, as it helps create a barrier that both hinders the defender and aids the attacker.

I suspect that prior attempted implementations of the pointy chain may have ignored the presence or absence of a congestion point pawn, and therefore failed as a result. Another point of failure may involve incorrectly defining the opposing King's danger zone relative to the pointy chain, but more on this later.

In part 2, later on, I'd like to go over pointy chains directed at the Queenside, and further elaborate on congestion points.

(End of part 1 here)

Regards,
CL

[Lyudmil Tsvetkov]

I'd like to go over the pointy chains issue again, this time attempting to break it down into finer details, which will hopefully assist others in their understanding, and (why not?) perhaps clear the path for improved coding implementations down the line.

This is not aimed at any particular engine or programmer, but an open-ended discussion that others should chime into with further on-topic comments or observations.

Firstly, I'd like to start off with a basic diagram illustrating a pointy chain that's directed at the enemy Kingside. (By the last statement, I mean that the Black King is situated on the short side of the board relative to the White pawn chain, namely on the g or h file) Let's not assume that these are the only pieces present on the board - indeed, if that were the case, there would hardly be any advantage conferred by the pointy chain.

[D]6k1/6pp/5p2/4pP2/3pP3/3P2P1/7P/6K1 b - - 0 1

The above position was arrived at after White's f4-f5, thus favorably 'extending the pawn chain'. Assuming sufficient material is on the board (i.e. especially the Queen and a bunch of other pieces - but more on this later), it is my contention that the d3-e4-f5 White chain is not only superior to the (longer) Black chain (g7-f6-e5-d4), but actually should give White a clear advantage due to far better Kingside attacking chances. The same considerations would hold true if the position was horizontally mirrored, and Black had the pointy chain directed at the White Kingside, as in the King's Indian proper. Also, I should quickly mention that the offensive pointy chain should contain at least 3 chain pawns, since a 2-pawn chain is much easier to undermine and would confuse the issue.

There's one more essential element present in the set-up in the above diagram that helps tip the balance in favor of the pointy chain directed at the Kingside, which I have not mentioned yet. [Without this element, the the position would likely be up for grabs, and the correct evaluation would probably depend on a myriad of other factors, rendering the whole pointy chain idea far less effective.] I invite the reader to take a good look at the position and try to determine what it might be.

OK, let's now compare the previous diagram with this one:


[D]6k1/6pp/5p2/2p2P2/3pP3/3P2P1/7P/6K1 b - - 0 1

We still have a pointy chain aimed at the Kingside, following the f4-f5 advance, but something is seriously amiss. There is no longer a black pawn on e5, and this should throw White's set-up for a loop. Again, it's my contention that that the pointy chain is no longer so favorable, as Black can use the open square on e5 in a number of ways to come up with effective counterplay.

So, it seems that our pointy chain concept really hinges on the presence of this pawn on e5. Here I would like to define a new term to aid us in our understanding - I'd like to call such a pawn as the one on e5 a congestion point, and it can be a favorable or unfavorable feature of the position depending on which way the chains are pointing, relative to the opposing Kingside.

While at it, let's come up with a better term for the foremost pawn at the tip of our pointy chain - I'd like to call it the spearhead. This will help us to better define the congestion point as the pawn directly in front of the chain pawn that is defending the spearhead. Its presence next to the spearhead is essential to the effectiveness of pointy chains in general, as it helps create a barrier that both hinders the defender and aids the attacker.

I suspect that prior attempted implementations of the pointy chain may have ignored the presence or absence of a congestion point pawn, and therefore failed as a result. Another point of failure may involve incorrectly defining the opposing King's danger zone relative to the pointy chain, but more on this later.

In part 2, later on, I'd like to go over pointy chains directed at the Queenside, and further elaborate on congestion points.

(End of part 1 here)

Regards,
CL

Thanks for the discussion, Carl!

Wholehearted applause.

I hope at least 5 parts are in store for us.

I guess you will not mind if I add my 2 cents.

[D]6k1/6pp/5p2/4pP2/3pP3/3P2P1/7P/6K1 b - - 0 1
d3-e4-f5 white chain, or otherwise, e4 defended pawn, and f5 defended pawn, and e4 defending f5 (as f5 could also be defended by g4, not quite to the point) = score pointy chain

Completely agree, you need at least 3 pawns for a meaningful pointy chain, and, necessarily, those pawns should be relatively advanced, at least one of them on the 5th or 6th ranks.

So again, pointy chain =

- e4 defended pawn, and f5 defended pawn, and e4 defending f5, or
- f5 defended pawn, and g6 defended pawn, and f5 defending g6 (as it might also be defended by h5 otherwise), or
- d4 defended pawn, and e5 defended pawn, and d4 defending e5, or
- e5 defended pawn, and f6 defended pawn, and e5 defending f6

That is it.
Plus the mirror chains from black's point of view.

As kingside castling is to be seen in 95% of cases, you might well skip other relevant chains here.

And, after you easily define the 4 most important pointy chains, you give the bonus for such a condition, maybe some 30cps.

[D]6k1/6pp/5p2/2p2P2/3pP3/3P2P1/7P/6K1 b - - 0 1

Here I do not agree: a pointy chain is a pointy chain, no matter what other conditions you have, just as a backward pawn is a backward pawn, and an isolated pawn an isolated pawn.

As long as you have one of the above conditions, e4 defended pawn, and f5 defended pawn, and e4 defending f5, which is true for the above diagram, you score a pointy chain and give the bonus.

The e5 square might be occupied beneficially by a black knight or bishop, but that is another thing, which receives bonus/penalty apart.

So far so good, we always miss something, no matter how hard we try.

[carldaman]

I'd like to go over the pointy chains issue again, this time attempting to break it down into finer details, which will hopefully assist others in their understanding, and (why not?) perhaps clear the path for improved coding implementations down the line.

This is not aimed at any particular engine or programmer, but an open-ended discussion that others should chime into with further on-topic comments or observations.

Firstly, I'd like to start off with a basic diagram illustrating a pointy chain that's directed at the enemy Kingside. (By the last statement, I mean that the Black King is situated on the short side of the board relative to the White pawn chain, namely on the g or h file) Let's not assume that these are the only pieces present on the board - indeed, if that were the case, there would hardly be any advantage conferred by the pointy chain.

[D]6k1/6pp/5p2/4pP2/3pP3/3P2P1/7P/6K1 b - - 0 1

The above position was arrived at after White's f4-f5, thus favorably 'extending the pawn chain'. Assuming sufficient material is on the board (i.e. especially the Queen and a bunch of other pieces - but more on this later), it is my contention that the d3-e4-f5 White chain is not only superior to the (longer) Black chain (g7-f6-e5-d4), but actually should give White a clear advantage due to far better Kingside attacking chances. The same considerations would hold true if the position was horizontally mirrored, and Black had the pointy chain directed at the White Kingside, as in the King's Indian proper. Also, I should quickly mention that the offensive pointy chain should contain at least 3 chain pawns, since a 2-pawn chain is much easier to undermine and would confuse the issue.

There's one more essential element present in the set-up in the above diagram that helps tip the balance in favor of the pointy chain directed at the Kingside, which I have not mentioned yet. [Without this element, the the position would likely be up for grabs, and the correct evaluation would probably depend on a myriad of other factors, rendering the whole pointy chain idea far less effective.] I invite the reader to take a good look at the position and try to determine what it might be.

OK, let's now compare the previous diagram with this one:


[D]6k1/6pp/5p2/2p2P2/3pP3/3P2P1/7P/6K1 b - - 0 1

We still have a pointy chain aimed at the Kingside, following the f4-f5 advance, but something is seriously amiss. There is no longer a black pawn on e5, and this should throw White's set-up for a loop. Again, it's my contention that that the pointy chain is no longer so favorable, as Black can use the open square on e5 in a number of ways to come up with effective counterplay.

So, it seems that our pointy chain concept really hinges on the presence of this pawn on e5. Here I would like to define a new term to aid us in our understanding - I'd like to call such a pawn as the one on e5 a congestion point, and it can be a favorable or unfavorable feature of the position depending on which way the chains are pointing, relative to the opposing Kingside.

While at it, let's come up with a better term for the foremost pawn at the tip of our pointy chain - I'd like to call it the spearhead. This will help us to better define the congestion point as the pawn directly in front of the chain pawn that is defending the spearhead. Its presence next to the spearhead is essential to the effectiveness of pointy chains in general, as it helps create a barrier that both hinders the defender and aids the attacker.

I suspect that prior attempted implementations of the pointy chain may have ignored the presence or absence of a congestion point pawn, and therefore failed as a result. Another point of failure may involve incorrectly defining the opposing King's danger zone relative to the pointy chain, but more on this later.

In part 2, later on, I'd like to go over pointy chains directed at the Queenside, and further elaborate on congestion points.

(End of part 1 here)

Regards,
CL

Thanks for the discussion, Carl!

Wholehearted applause.

I hope at least 5 parts are in store for us.

I guess you will not mind if I add my 2 cents.

[D]6k1/6pp/5p2/4pP2/3pP3/3P2P1/7P/6K1 b - - 0 1
d3-e4-f5 white chain, or otherwise, e4 defended pawn, and f5 defended pawn, and e4 defending f5 (as f5 could also be defended by g4, not quite to the point) = score pointy chain

Completely agree, you need at least 3 pawns for a meaningful pointy chain, and, necessarily, those pawns should be relatively advanced, at least one of them on the 5th or 6th ranks.

So again, pointy chain =

- e4 defended pawn, and f5 defended pawn, and e4 defending f5, or
- f5 defended pawn, and g6 defended pawn, and f5 defending g6 (as it might also be defended by h5 otherwise), or
- d4 defended pawn, and e5 defended pawn, and d4 defending e5, or
- e5 defended pawn, and f6 defended pawn, and e5 defending f6

That is it.
Plus the mirror chains from black's point of view.

As kingside castling is to be seen in 95% of cases, you might well skip other relevant chains here.

And, after you easily define the 4 most important pointy chains, you give the bonus for such a condition, maybe some 30cps.

[D]6k1/6pp/5p2/2p2P2/3pP3/3P2P1/7P/6K1 b - - 0 1

Here I do not agree: a pointy chain is a pointy chain, no matter what other conditions you have, just as a backward pawn is a backward pawn, and an isolated pawn an isolated pawn.

As long as you have one of the above conditions, e4 defended pawn, and f5 defended pawn, and e4 defending f5, which is true for the above diagram, you score a pointy chain and give the bonus.

The e5 square might be occupied beneficially by a black knight or bishop, but that is another thing, which receives bonus/penalty apart.

So far so good, we always miss something, no matter how hard we try.

So again, pointy chain =

- e4 defended pawn, and f5 defended pawn, and e4 defending f5, or
- f5 defended pawn, and g6 defended pawn, and f5 defending g6 (as it might also be defended by h5 otherwise), or
- d4 defended pawn, and e5 defended pawn, and d4 defending e5, or
- e5 defended pawn, and f6 defended pawn, and e5 defending f6

Yes, that's basically the attacking chains in a nutshell. Was gonna get to it in a future post, but I appreciate your prompt input. I even had the same type of bonus in mind, 30-40 cps at a minimum, probably slightly more for the spearheads that are closer to the opposing King.

[D]6k1/6pp/5p2/2p2P2/3pP3/3P2P1/7P/6K1 b - - 0 1

Here I do not agree: a pointy chain is a pointy chain, no matter what other conditions you have, just as a backward pawn is a backward pawn, and an isolated pawn an isolated pawn.

As long as you have one of the above conditions, e4 defended pawn, and f5 defended pawn, and e4 defending f5, which is true for the above diagram, you score a pointy chain and give the bonus.

The e5 square might be occupied beneficially by a black knight or bishop, but that is another thing, which receives bonus/penalty apart.

Of course, I'm assuming a congestion point is present, or else I'm not sure how much the pointy chains are worth. You may be the right that they're still worth something, but I think it's less than half at best if there's a hole in the barrier. Don't forget that it's not just a Knight landing on e5 that should worry us, but also the open b8-h2 diagonal that is ripe for a Queen-Bishop battery, a potential thorn right into our Kingside.

I'm just concerned that an improper weight here can break the implementation. With the normal congestion point on e5, Black does not get any meaningful counterplay, on the other hand. Big difference in my opinion.

Actual concrete examples coming up in part 2. Stay tuned.

[Lyudmil Tsvetkov]

Staying tuned, Carl.

A spearhead closer to the enemy king should also get a bigger bonus as a storming pawn, so we must be careful here to award only and exclusively the pointy chain ability.

Btw., Carl, just to ask you, as foremost language expert, the term is yours, I like it very much, however, should not it be pointed chain rather than pointy chain?

If you ask me, the first one is the better choice. The second one is too colloquial.

OK, just to ask programmers again, what is so difficult in implementing a simple rule like that:

Pointed chain bonus

Whenever you find:

- e4,f5 and g6 pawns at the same time, or
- d3,e4 and f5 pawns, or
- d4,e5 and f6 pawns, or
- c3,d4 and e5 pawns

with the respective mirrored cases for black,

you give some additional 30cps bonus for the presence of a pointed chain.

That is it. You do not care about the location of the king, as in 95% of cases the kings will be found on the king side, and that will save you computational time. You do not care about the queen side. You just define those 4 basic and most useful chain types.

You also do not care in the least if the pawns of the chain are blocked, not blocked, or partially blocked, as all of those cases are fully realistic, might somewhat change the added value of the chain, but in all cases a bonus is due.

Below the basic 4 pointed chains:

[d]6k1/8/8/5P2/4P3/3P4/8/6K1 w - - 0 1

[d]6k1/8/6P1/5P2/4P3/8/8/6K1 w - - 0 1

[d]6k1/8/8/4P3/3P4/2P5/8/6K1 w - - 0 1

[d]6k1/8/5P2/4P3/3P4/8/8/6K1 w - - 0 1

SF tried in the past with something similar, though, as far as I remember, they used fewer pawns to define the chains, and also made use of the king location, which only increased computational costs.

I think the above suggestion is much more realistic to implement, but who knows?

So again, here you have a very simple pointed chain rule, that should hold true in most occasions.

Can anyone tell me, what is so difficult about this to implement?

Can you, Pawel?[/b]

[Lyudmil Tsvetkov]

Another meaningful suggestion, if engines already have some kind of chain pawns eval that might interfere with a further pointed chain bonus, why not try giving a very small bonus at first, 5-8cps or so, or even 2cps, just to check if there is any added value to this particular placement of pawns?

Maybe some value will work after all?

[carldaman]

Hi again Lyudmil,
I like pointy more actually, as pointed, although perfectly synonymous, is perhaps too stilted. Maybe it's only because I've grown fond of pointy, and it stands out better to me. I'm not even sure if I was the first one to come up with the term - but my memory is not what it used to be, anyway.

I have to say that I am a big stickler when it comes to the King's position relative to the chain. I could be wrong, but I believe the road to a successful implementation is to have definitions that are as specific as possible, without letting things become too 'granular'.

I agree we have to be somewhat careful about overlapping with storming pawns -- would you say that any spearhead that's on the 6th rank does that?

Staying tuned, Carl.

A spearhead closer to the enemy king should also get a bigger bonus as a storming pawn, so we must be careful here to award only and exclusively the pointy chain ability.

Btw., Carl, just to ask you, as foremost language expert, the term is yours, I like it very much, however, should not it be pointed chain rather than pointy chain?

If you ask me, the first one is the better choice. The second one is too colloquial.

OK, just to ask programmers again, what is so difficult in implementing a simple rule like that:

Pointed chain bonus

Whenever you find:

- e4,f5 and g6 pawns at the same time, or
- d3,e4 and f5 pawns, or
- d4,e5 and f6 pawns, or
- c3,d4 and e5 pawns

with the respective mirrored cases for black,

you give some additional 30cps bonus for the presence of a pointed chain.

That is it. You do not care about the location of the king, as in 95% of cases the kings will be found on the king side, and that will save you computational time. You do not care about the queen side. You just define those 4 basic and most useful chain types.

You also do not care in the least if the pawns of the chain are blocked, not blocked, or partially blocked, as all of those cases are fully realistic, might somewhat change the added value of the chain, but in all cases a bonus is due.

Below the basic 4 pointed chains:

[d]6k1/8/8/5P2/4P3/3P4/8/6K1 w - - 0 1

[d]6k1/8/6P1/5P2/4P3/8/8/6K1 w - - 0 1

[d]6k1/8/8/4P3/3P4/2P5/8/6K1 w - - 0 1

[d]6k1/8/5P2/4P3/3P4/8/8/6K1 w - - 0 1

SF tried in the past with something similar, though, as far as I remember, they used fewer pawns to define the chains, and also made use of the king location, which only increased computational costs.

I think the above suggestion is much more realistic to implement, but who knows?

So again, here you have a very simple pointed chain rule, that should hold true in most occasions.

Can anyone tell me, what is so difficult about this to implement?

Can you, Pawel?[/b]

[carldaman]

Another meaningful suggestion, if engines already have some kind of chain pawns eval that might interfere with a further pointed chain bonus, why not try giving a very small bonus at first, 5-8cps or so, or even 2cps, just to check if there is any added value to this particular placement of pawns?

Maybe some value will work after all?

Probably the above was mainly addressed to others, but for those who have not implemented pointy chains at all, I think 30-40 cps can't be too far off. Most engines, including top ones, give ridiculously lopsided evaluation scores in the KID, not favoring the attacking chains at all, so a significant correction is in order. That will likely not happen if the bonuses are too low.

In part 2, I'd also like to address incremental bonuses/penalties. Coming up a bit later... I'm not exactly a fast mover 'n shaker.

[Lyudmil Tsvetkov]

Hi again Lyudmil,
I like pointy more actually, as pointed, although perfectly synonymous, is perhaps too stilted. Maybe it's only because I've grown fond of pointy, and it stands out better to me. I'm not even sure if I was the first one to come up with the term - but my memory is not what it used to be, anyway.

I have to say that I am a big stickler when it comes to the King's position relative to the chain. I could be wrong, but I believe the road to a successful implementation is to have definitions that are as specific as possible, without letting things become too 'granular'.

I agree we have to be somewhat careful about overlapping with storming pawns -- would you say that any spearhead that's on the 6th rank does that?

I think this is a serious issue, and we have to resort to Graham to decide if pointy or pointed is the right term.

I bet Graham will support me.

Could you please explain what a stickler is?

Yes, any spearhead on the 6th rank does that, but also f5/f4 spearheads on the 5th rank. Not so an e5 spearhead.

[Lyudmil Tsvetkov]

Another meaningful suggestion, if engines already have some kind of chain pawns eval that might interfere with a further pointed chain bonus, why not try giving a very small bonus at first, 5-8cps or so, or even 2cps, just to check if there is any added value to this particular placement of pawns?

Maybe some value will work after all?

Probably the above was mainly addressed to others, but for those who have not implemented pointy chains at all, I think 30-40 cps can't be too far off. Most engines, including top ones, give ridiculously lopsided evaluation scores in the KID, not favoring the attacking chains at all, so a significant correction is in order. That will likely not happen if the bonuses are too low.

In part 2, I'd also like to address incremental bonuses/penalties. Coming up a bit later... I'm not exactly a fast mover 'n shaker.

Its the search, Carl.

All engine searches are tuned and finetuned to specifically yield good results in open positions, and, as good move candidates in open and closed positions significantly differ, that means that, even if you implement a good positional eval term like pointed chain bonus, for example, all tests will still fail, as the engine will not know how to make use of the bonus, and what moves to search first.

Tune the search simultaneously while introducing new positional terms, so that moves searched first are appropriate for more closed and more open positions at the same time, and, as Pawel says, the pointed chain bonus, even in its simplest form of bonussing 4 or 5 main pointed triades without caring about the position of the king, will work like a charm.

[carldaman]

I'd like to go over the pointy chains issue again, this time attempting to break it down into finer details, which will hopefully assist others in their understanding, and (why not?) perhaps clear the path for improved coding implementations down the line.

This is not aimed at any particular engine or programmer, but an open-ended discussion that others should chime into with further on-topic comments or observations.

<snip>


In part 2, later on, I'd like to go over pointy chains directed at the Queenside, and further elaborate on congestion points.

(End of part 1 here)

Regards,
CL

Alright, now I would like to take a look at the world of pawn chains facing towards the Queenside (more precisely - towards the side of the board where the opposing King is not located).


I'll actually show a couple of notable examples from recent engine games.

[D]r1b2rk1/ppq1bpp1/2n1pn1p/3pN3/2pP1P2/2PBPQ2/PP1N2PP/R1B2RK1 w - - 0 11

In the above diagram, Fizbo 1.31, playing black, has just extended its chain (with tempo, no less) by playing c5-c4. This sort of move is probably as old as computer chess, and is typically seen in Stonewall and French formations. [I remember witnessing old forum discussions from long ago that touched on the need of keeping the engines from making such moves.] Not much has changed in this regard over the years.

Most engines, even very strong ones will routinely play like this when it comes to extending a pawn chain on the Queenside, but will balk at (correctly) doing the same thing on the Kingside! Obviously, something is really wrong, but the solution to this problem is by no means obvious.

Before a solution can be tackled in earnest, a better understanding of the elements of such positions can be very useful. So what do we have here?

Black has just extended his chain, but once the Bishop retreats to c2, it has not achieved anything except maybe gaining some space, away from the opposing King, however. What about the White pawn chain (b2-c3-d4)? It does not look all that impressive, but it can still be extended forward if e3-e4-e5 can be played. Even without the White e-pawn advance, the Black chain (f7-e6-d5-c4) is acting as a barrier that restricts most of his pieces to the Queenside, while White has more freedom to act and better chances on the Kingside, which should count for more.

So, a penalty for extending the pawn chain in the wrong direction is owed to Black, even though there is no White "pointy" chain spearheaded on Black's side of the board! I purposely picked a Stonewall position because it illustrates this very fact. I would suggest a 20 cps penalty to Black for playing c5-c4, which could be increased to 30 cps if White succeeds in getting a pawn to e5, AND thereby extending his chain, aimed at the Kingside.

Now, let's take a look at the next position, arrived at just a few moves later:

[D]r1b2rk1/p3bpp1/2q1pn1p/3pP3/1ppP1P2/2P2Q2/PPBN2PP/R1B2RK1 b - - 0 14

Lo and behold, White (represented by the wonderfully improved engine Andscacs 0.72) has gotten his e-pawn to e5, extending his chain in the right direction. We reward him with an additional bonus, bringing it to at least 30 cps. [Earlier we'd already given a penalty to Black for c5-c4 of about 20 cps, which translated into an equal bonus to White. Now we increase this bonus based on the e-pawn advancing to e5.] Andscacs went on to win a nice game from this position.


Next, I'd like to discuss congestion points from the perspective of a pawn chain pointed at the Queenside. We'll again use a game played by Andscacs, this time with Black.

[D]r1b2rk1/1pq1b1pp/2n1p3/p1ppPp2/P4P2/2PBP2P/1PQN2P1/R1B2RK1 b - - 0 13

In the above diagram, a piece exchange has taken place on e5, and Black still has the option to extend his chain by playing c5-c4 (and again, with tempo). Would such a move incur a similar penalty as before? If not, why not?

Some significant differences are present. There is no longer a congestion point on d4, where it would normally be after c5-c4, since White has already recaptured dxe5. Moreover, White will need help from Black if he is ever going to build a meaningful (of 3 pawns or more) chain directed at Kingside, by being able to somehow make an exd4 capture. This is not likely to happen here; instead, the a7-g1 diagonal will be used by Black to create counterplay.

Under the circumstances, I propose that no penalty be given to c5-c4, for the reasons specified, in particular because of the lack of a congestion point on d4.


[D]r1b2rk1/1p4pp/1qn1p3/p1bpPp2/P1pN1P2/2P1P2P/1PQ1B1P1/R1B2RK1 b - - 0 16

Now, let's take a look at the position a few moves later. Black (Andscacs) has indeed developed counterplay on the a7-g1 diagonal and despite the Knight on d4, White will see his central pawn structure totally shattered after Black's g7-g5!

Andscacs again won convincingly over Fizbo (time control was 25 min + 15 sec inc on an i3.)


To conclude this second part, I'll reiterate the importance of congestion points to directional pawn chains. If a congestion point is not present, both the positive and negative effects of pointy (or pointed) pawn chains are reduced or outright eliminated. In the case of Kingside-aiming chains, I will partially agree with Lyudmil and still award half the normal bonus (half of 30-40 cps), because of the practical attacking chances offered by the pointy chain even under less optimal circumstances.

I've changed the title of the thread a little bit [basically reverting to the original title I had in mind], to reflect the action of extending the pawn chain as these chains don't appear out of thin air, and a real choice has to be made whether to extend a chain or not, and since I'm a believer in concepts more so than the names we actually come up with to describe them, which are highly subjective anyhow. Pointy or pointed, who cares?

(end of part 2, more to follow when I have time)

Regards,
CL