Identifying weak squares

[mvanthoor]

An excellent exposé about the Maroczy Bind, which I enjoyed reading. It made me more convinced that calling something a weak square using the official definition, and how weak that square actually is are sometimes two different things.

They are.

Let me give an example. Consider e4, with pawns on d3 and f3. That square is going to be stronger (less weak) than one which is only supported by d3. Then factor in all the pieces defending that square, and you have a monster strong square!

Yes. The Maroczy Bind actually illustrates this as well. c4 and e4 control d5. Nb1c3 will also control d5. After exchanging the d2 pawn, the rook on d1 will both cover d3, d4, AND d5.

I would be interested if you agree with the above, that the official definition of weak is just a binary "weak or not" distinction, altogether different from reality where things are a lot more granular.

Of course it's more granular than a square just being weak or not, I agree.

The definition "A square is weak when it can never be defended by a pawn" highlights the fact that you have to defend it with something else; at least a knight or a bishop. It just means you will have to keep an eye on such a square, and be ready to defend it if you need to.

If you had a pawn pointing at that square, it would not be weak, especially if the opponent didn't have his own pawn to attack it. The reason why a square is strong when defended by a pawn is that the opponent can't put a piece on it without losing it immediately. (Barring special circumstances such as pins or tactical shots.)

"A square is weak when it can never be defended by a pawn" is just one of the many thumb rules of chess. It's true MOST of the time, but there are positions where this rule, while true, just doesn't have a lot of impact anymore because of the state of the rest of the board.

How you weigh the importance of all the thumb rules in any given position, in combination with how far you can look ahead, determines how strong you are at chess. You could have read 500 books and still play at 1200 level. You could also read a sheet of A4 with the most important thumb rules listed, and be able to weigh them perfectly, 12 moves into the future. That's how a 14 year old grandmaster is made. Not by reading 500 books (you can't at 14), but by being able to weigh the importance of a lot of the rules lots of moves into the future.

[Jon12345]

And I am trying to find those exceptions, so I can get a precise definition of a weak square, and different levels of weakness.

So it seems that f4, g4, and h4 means that g3 and h3 are not "classically" weak, since you have to come in from the side. Perhaps slightly weak. And what about c3, d4, and e3...is d3 weak?

[mvanthoor]

And I am trying to find those exceptions, so I can get a precise definition of a weak square, and different levels of weakness.

I wouldn't try to encode that in your chess engine... you'll have a horrible time.

So it seems that f4, g4, and h4 means that g3 and h3 are not "classically" weak, since you have to come in from the side.
Perhaps slightly weak.

For a chess engine, you could maybe redefine a "weak square" as "A square that can never be defended by a pawn again AND there's a pawn on the same file behind the square."

And what about c3, d4, and e3...is d3 weak?

Yes. d3 is called a hole. If black has pawns on c4 and e4 especially, it's a great place to (again) plant a knight. If it's exchanged, there's a black pawn on d3, covered by either e4 or c4. That's probably going to be very bothersome.

[Jon12345]

That has brought up another thing...what if you have pawns on c4 and e4, no d pawn and no b and f pawns. Does that mean that c3 and e3 are considered weak squares under the classical definition?

[mvanthoor]

That has brought up another thing...what if you have pawns on c4 and e4, no d pawn and no b and f pawns. Does that mean that c3 and e3 are considered weak squares under the classical definition?

Lke this?

[d]6k1/pp3pp1/2p5/8/2P1P3/8/P5PP/6K1 w - - 0 1

c3, d3, d4 and e3, are weak.
Pawns c4 and e4 are isolated.
c5 and e5 are outposts for black, because they can never be attacked by a pawn.
White has 4 pawn islands, black has 2.

Imagine some extra pieces in addition to the pawns, and you'd see that white is in a very bad position here.

[Jon12345]

Yes, it does look a little "airy" around those pawns!

I think I now have a good handle on weak pawns, thanks very much! Interesting discussion and I wonder what stage in someones chess development they start factoring in weak squares to their position evaluation. Stab a guess at their elo rating on lichess or chess.com?

[mvanthoor]

Yes, it does look a little "airy" around those pawns!

I think I now have a good handle on weak pawns, thanks very much! Interesting discussion and I wonder what stage in someones chess development they start factoring in weak squares to their position evaluation. Stab a guess at their elo rating on lichess or chess.com?

I have no idea. My rating is somewhere around 1835 when I'm not making much of an effort and just play by 'gut feeling.' When I start paying attention to some positional factors and actually calculating moves further ahead than 5-6 ply, my rating can go up to 2000. I don't know how strong I could be in a long over the board game when I *really* make an effort and try to apply what I know... most of the time, I'm either too lazy, or I don't have the time to sit down and play a 4 hour game.

And I don't like to play against other people. I've not played anyone in chess since I quit tournaments around 2000. (And yes, one of the reasons is that I can't just turn a human off and walk away when at move 24 I suddenly don't feel like finishing the game for whatever reason.)

[Jon12345]

I'm the opposite in that I don't like playing the computers! My local chess club has a Zoom meet and match every Friday, which is fun. About 25 players in it, playing one another.

I'm currently 2162 for Rapid on lichess. I've gone up 263 elo in the last 12 months, by playing some online tournaments. At age 56, I feel good about my progress. I am hoping to get to perhaps 2300 in a years time, or maybe more. My blitz strength is not as good, and I definitely notice the clock speed of my brain is slower nowadays than in my youth!

[mvanthoor]

I'm the opposite in that I don't like playing the computers! My local chess club has a Zoom meet and match every Friday, which is fun. About 25 players in it, playing one another.

That's another point. I have too many things going on at the moment to go to a chess club and sit down for a 4 hour game at a predetermined time and date. Who says I _want_ to play a game that day? Who says I _want_ to even start a game at 20:00 lasting until 0:00, when I just finished work at 17:30 or so, have to go to work the next day?

I'm currently 2162 for Rapid on lichess. I've gone up 263 elo in the last 12 months, by playing some online tournaments. At age 56, I feel good about my progress. I am hoping to get to perhaps 2300 in a years time, or maybe more. My blitz strength is not as good, and I definitely notice the clock speed of my brain is slower nowadays than in my youth!

Congratulations on the progress. Just keep in mind that a lichess rating has no bearing on your over the board Fide or USCF or DWZ (or whatever country's over the board rating system is). You can only compare ratings between members within the same rating pool. The only thing you can say is: if you are +50 Elo on lichess against person X, you will probably also be +50 Elo against that person X if you'd play on chess.com, or over the board. What your chess.com ratings or OTB ratings would be, is completely disconnected from you lichess ratings; the only thing is that they'll probably be roughly 50 Elo apart in your advantage.

I don't chess online. I've had a long chess playing hiatus between 2000 and 2007, and at that point I bought a DGT-board to play against some of the weaker engines. I like playing against engines in the 1500-2000 CCRL range. (I actually now have two of my own ) For some reason, when playing on a computer, I miss lots of moves that I don't miss when playing on a real board. It's probably what you're used to. I only use the computer to see where I made huge mistakes.

Very often I play games where I go with one of the top 3 moves for 3/4ths of the game with sometimes a slip to the 4th or 5th move. Then suddenly I either miss something, or calculate a combination of which I'm certain it works... but it doesn't, because the computer saw the ONE in-between move I didn't, which costs me the game.

With regard to brain speed... I'm about 15 years younger than you are, and if I need more than about 3 seconds to understand something, I feel like an idiot already. The fact is though, that I'm now engaging in a style of programming / software that I haven't touched since my university days. You don't write alpha-beta functions or board representations at work, unless your a board game programmer...

[Jon12345]

Yes, aware of the differences between a fide grade and lichess. I've done a bit of research on people trying to create tools to calculate one from the other, but the results seem to be a bit all over the place. I took a long time off chess too, from age 23 to about 43. When I came back, it took me years and years to improve my strength again. I was blundering all over the place and playing really slowly.

I have to say it must be great fun playing against your own creation! Have you ever thought about creating a range of PSQT so that you could randomly choose between different playing styles? If I had an engine, I would love to do that. It reminds me a bit of what Chessmaster2000 use to do, where you could pick an opponent, such as the one who favoured Knights.