# Question
Title: What is the key idea for winning with KQ against KBN? (How to break the barrier?)
Mastering winning with KQ versus KR is one of my biggest daydreams. Well, in a few particular cases I was able to checkmate (after reaching Philidor and then capturing the rook), but that was just a single specific line of black's response. (And I want to know a full algorithm.) It seems that the endgame is terribly difficult. I'll keep continue watching YouTube videos though.

I have another but similar question: what about KQ against KBN?

E.g. this interactive puzzle:

https://www.chessvideos.tv/endgame-training/queen-vs-bishop-knight-h-pawn-13.php

```
[Title "White to play and win"]
[fen "8/1kn4p/2b5/8/8/8/4KQ2/8 w - - 0 1"]

```

I usually start with 1. Qh4 (bishop cannot defend it, because we'll take the bishop instead...). Then, on my second move, I take the pawn (2. Qxh7). After that, I have no good ideas. Either I am too silly or this is a pretty hard endgame. Bishop and knight together form a strong barrier.

What you've learnt, you'll forget; what you've understood, you'll remember. I am trying to understand rather than to memorize what I should do.

# Answer
First some guidelines:

1. Ideally black wants to build a fortress round the king with the bishop, knight and pawn. The pawn is too far away so it will have to be just the bishop and knight
2. The black pawn is a long way from queening so it is a low priority. No need to chase it just yet. If black tries too hard to defend it that will take a piece (probably the bishop) away from the defence of the king.
3. White wants to try and checkmate. For that the white king is going to have to be close to the black king. Currently they are a long way apart and the kings move slowly so first priority is probably to get the white king closer
4. Once the white king and queen are close to the black king it becomes much more difficult for the black pieces to retain coordination in protecting the black king. Try and force a zugzwang where one of the pieces has to move away from the king and fall to a queen fork.

Here's what I got trying this against the interactive puzzle:

```
[fen "8/1kn4p/2b5/8/8/8/4KQ2/8 w - - 0 1"]

1. Kd3 Nb5 2. Qb2 h5 3. Kc4 Be8 4. Kc5 Kc7 5. Qe5+ Kd8 6. Qg5+ Kc7 7. Qe7+ Bd7 {I want this position with black to move to force the knight to move so time for some triangulation} 8. Qf6 Be8 9. Qf8 Bd7 10. Qe7 Na3 11. Qe5+ Kd8 12. Qg5+ Ke8 13. Qe3+ Kf7 14. Qxa3 Kg6 15. Kd6 Bb5 16. Ke5 Bc4 17. Qf3 Ba2 18. Qf6 Kh7 19. Qg5 Bb1 20. Kf6 Bg6 21. Qxg6+ Kh8 22. Qg7#

```
> 2 votes

---
Tags: endgame
---


# Question
Title: How to play Botvinnik-Carl's defence in the Caro-Kann when White responds with 4. c3?
In the Caro-Kann, Botvinnik-Carl's defence, Black typically wants White to take on c5 so Black can play e6, preparing Bxc5 and Nc6. However, I have been seeing the move c3 after c5 a lot.

How can I deal with White's supporting of their center pawn chain?

```
[FEN ""]

1. e4 c6 2. d4 d5 3. e5 c5

```

# Answer
The move 4. c3 does two things:

* it supports the white center
* it states that white is not willing to take on c5

It is especially the latter, which is crucial. If white doesn't want to take and keep his centre intact black can play a "sort-of french" setup but without blacks biggest shortcoming there: the light-quared bishop and its lack of options. If white is not willing to take on c5 on move 4 he won't do so on move 5 or 6 either, hence:

```
[FEN ""]

1. e4 c6 2. d4 d5 3. e5 c5 4. c3 Nc6 5. Nf3 Bg4  6. Be2 e6!?

```

Develop the bishop c8 (to f5 or, after Nf3, to g4), **only then** play e6, arriving at a "french defense, advance variation", but without the bad bishop. The rest of the pieces develop like in the french defense: Nb8 goes to c6, Ng8 goes to e7 and f5 eventually (in rare cases to g6), Bf8 to e7, etc.. The plans are similar too: put pressure on the white centre with the levers c5 (this is already played) and f7-f6. If the bishop g4 is attacked or questioned with h3 it is probably best to exchange it for the Nf3, thereby diminishing whites control of the dark squares in the center (d4, e5). Retreating it to g6 would take possible squares away from the Ng8 to go to. Also, expand on the queen side where you have a space advantage.
> 3 votes

---
Tags: opening, analysis, caro-kann
---


# Question
Title: What chess software allows to search for sacrifices and combinations?
I want to search a database of games for generic interesting tactics combinations. What are my software options for this (SCID/CB/CA)? Is there a published algorithm/script that determines that a move is a sacrifice/combination? I see that Chessbase allows this: as per http://help.chessbase.com/Reader/12/Eng/index.html?search\_sacrifices.htm, but I would be curious to see if other software does something similar, and also want to know more details behind these algorithms: "The ChessBase sacrifice search does a look-ahead in all tactical situations and for this reason takes somewhat longer than the other searches. The algorithms were written by Dr. Christian Donninger, the author of Nimzo."

# Answer
The http://ChessTempo.com tactis trainer is based on tactical problems extracted from a large database scanned with an engine and the problems have been tagged with tactical motifs by users. Perhaps it is sufficient for your purpose if you learn to create custom problem sets based on these tags. There is a discussion forum there where you can ask your question in detail.
> 2 votes

# Answer
Chessbase 17 exactly does what you want. I love this feature. I just added a recent search for sacrifice and this is the result, off course one from many. I have attached the screenshot for you to understand quickly. This sacrifice of bishop crashed the entire game of the black and in next move, he resigned. He placed his king on d-8.

http://help.chessbase.com/Reader/12/Eng/index.html?search\_sacrifices.htm
> 1 votes

---
Tags: software
---


title: Using chess for therapy?

text:
# Question
Title: Using chess for therapy?
Have there been any studies on using chess for therapy?

If so, what conditions or illnesses have benefited most from using chess as a therapy? Are there certain conditions or illnesses were it has actually been more stressful?

# Answer
> 9 votes
I am not an expert, but an active chess player at chess.com and participate in its forums. Yes, chess can be therapeutic. Playing chess involves co-ordination of different mental abilities like strategy, tactics, intuition, visual imagery, risk analysis, control of emotions, etc. Actively playing chess everyday keeps the mind sharp and attentive. In most cases, it has also shown improvements in mental conditions like ADHD, OCD, Depression, etc.

However, over indulgence into anything is bad and playing compulsively over long duration can effect the individual's thought process. Many schizophrenic persons who play chess start visualizing everything including this life, its people and events as chess moves. If the connection with chess is too deep, real life relations with people are affected. These studies are not confirmed, and are said to be more like "adding order to chaos" from schizophrenic mind's perspective.

# Answer
> 6 votes
Chess is especially great for men. As you may know, when men are stressed out by really big problems it helps to divert their attention to a hobby. That way they can be working to solve smaller problems. People say chess makes you think hard. I think the guys who play it actually want to relax. It's like watching football.

> ## "But I play chess to not think."
>
> --CLUB PLAYER

For me it becomes very zen, especially when just playing with my friends. In America our attitude is very task oriented or goal focused. When you're playing with a friend and you've got the game all wrapped up, it's more about being there. Asian cultures generally have this attitude. It's about the experience of the leaves, the air, the black tea, or the fountain behind you. The friendly curiosity of girls walking by on their way to class. Maybe the encouragement of a few spectators gathered around your board to watch.

# Answer
> 5 votes
Friends I really had an ill-fated childhood as one of my close relative was acute alcoholic and I had severe mental disorders like OCD and Social Anxiety. However with the help of caring people like parents and treatment in a international Bangalore based Deemed University today I walk free from the shackles of mental illness. I play chess for earning and I play it in India. No I am not that much successful and my ELO Rating is below 1800 but I enjoy playing the game . Though initially I had some problems regarding the physical aspect of competitive chess today with proper diet and exercise I have overcome that. Thankfully my chess coach is understanding and due to my exposure to life, chess has given me a new view to life. High level competitive chess is helping me to do my other works nicely as it is helping me to have a definite goal and structured thinking pattern. Obviously I do not practice for hours as that can be detrimental but I do practice for about 7-8 hours weekly. I know that to do well I should practice a little more, say about 15-16 hours per week but not more than that as everyone's brain has its limitations. Chess has really empowered me and due to the fact that I can count my blessings(that at least I am winning some games) I am happy with my life. Thank you chess.

# Answer
> 3 votes
There is a professional chess therapist out there.

http://web.archive.org/web/20170105171446/http://szachoterapia.pl/kontakt.html

NOTE: the original link is dead, and the website is only available on the Wayback Machine in Polish.

Let me quote the overview of her ideas from her website:

* chess is the bridge between the therapist and the world of the kid
* action on the board serves as an ice-breaker and stimulates the conversation
* initially the therapist plays passively and observes the child
* only much later the therapist raises the stress level by more active play
* this kind of interaction at the chessboard serves as a diagnostic tool
* the core of the method: new behaviors learned in chess transfer to the kid's real life
* chess therapy ignores correct chess from the competitive point of view

# Answer
> 1 votes
**I recommend to consult the book "Chess Therapy" by Fadul and Canlas. The book seems comprehensive to me** (in a first look). The wikipediea article looks good enough as a starting point (which seems to be largely based on the writings of the above two authors).

There are more recent articles, such as these two.

The articles on chess and psychoanalysis seems irrelevant for this question.

PS: Seeing the answer of MichalRyszardWojcik, I searched for journal articles that discuss it, and found one in Asian Journal of Psychiatry immediately, to my surprise: Chess therapy: A new approach to curing panic attack. But, it is a letter to the editor and is only anecdotal "evidence" (there are plenty of such resources).

---
Tags: psychology
---


title: Chess match between two smartphones

text:
# Question
Title: Chess match between two smartphones
I have two smartphones with different CPUs, GPUs, RAM etc...

How can I put them to play a chess match each other? By using different chess engines or the same one, with choosing CPU or GPU.

For example: Stockfish 15 in phone A GPU vs Stockfish 14 in phone B CPU.

Edit: They should play each other automatically, not manually by a human who will "transfer" the moves to each phone.

# Answer
If you want to do it manually,

You can install an engine of your choice onto each phone, start a match on each phone (one where the engine is playing white, and one where it is playing black) and simply input the first engine's move into the second engine, input its reply back into the first one and so on.

To do it automatically,

You can use the Universal Chess Interface. What exactly to do will depend on your specific use case and needs but you can read more about it here.
> 3 votes

---
Tags: engines, computer-chess
---


title: Pawn theory / exercises

text:
# Question
Title: Pawn theory / exercises
I am not a very strong positional player and I thought I could work on my pawn theory a bit. Are there common exercises or internet resources I could look into for how to play better pawn structures as well as make better pawn breaks?

# Answer
> 6 votes
*Pawn Structure Chess* by *Andrew Soltis* is a good book for start.

It teaches you how to play as Black **and** White in the following positions:

1. French defense-Advance variation
2. Caro-Kann pawn structure-including Panov attack
3. Slav defense
4. Open Sicilian defense and English opening
5. Closed Sicilian defense and English opening
6. King's Indian defense
7. Dutch "Stonewall"

To this day I was not able to find a better book written for this topic-it is clearly written and covers **most** of the important pawn structures.

**I would highly appreciate if other members can point out some other good books for this topic.**

Give it a chance-I am **100%** certain that you will not regret it.

Best regards.

# Answer
> 6 votes
Two other great books include

While these books are fantastic places to read about pawn play, they are **hard** to read if you're just getting started with pawn structures / strategy (where you usually will get overloaded with a ton of information without the kind of context that experienced players have to make sense of all the wonderful things that are said!)

So you might want to get your feet wet with NM Dan Heisman's famous Novice Nook articles which include some very easy-to-read instructional pieces on pawn breaks / weaknesses and more importantly, how weak players misuse their pawns.

Some key articles in this assortment include:

For added fun, grab a friend and practice Michael Goeller's Pawn Battle mini-game. It teaches you some fairly rudimentary ideas about pawn breaks, breakthrough sacrifices and zugzwang.

Another worthy pay-for resource are chess.com's chess mentor lessons and videos by some excellent GMs/FMs/IMs (especially IM Danny Rensch whose lectures on different pawn structures are very thorough and entertaining)

# Answer
> 2 votes
over 2 years too late to the party, but Axel Smith's 'Pump Up Your Rating' has a wonderful section dedicated to pawn levers. Such a great book!

# Answer
> 1 votes
Chess Structures – a Grandmaster Guide. Flores Rios, Mauricio (2015)

See my comment in the answer citing Soltis, above by AlwaysLearningNewStuff. I am not sure where is best, as this seems to be same level and purpose as the Soltis book cited, about Pawn structures that matter and can be seen in early phases of the game.

While the other answer is more specifically on endgame problems, and explicitly named endgame positions (e.g Philidor, Lucena) not as abstracted pawn structures, as above. Those are abstracting the rest of the material present on the position they are pointing to, as grouping the associated plans possible for all positions with similar pawn placements over whole board (left to experience, what similar might mean), which includes many placements for the other material types, not specified by the diagrams presented with the name of the structure.

I do think, that once one self assess own difficulty with pawns, that even endgame with pawns, or mini-games with pawns can also serve as possible basis for generalization to positions with similar pawn relative placement as those studies in endgames, but with other material on board as well, as elements of planning to stitch with other plans or differentially evaluate them. In that sense, endgame problems or study is not just about practical endgame winning.

Once one accept the notion of generalization and position abstractions, as objective of learning, I think that it does not matter that much to attach a specific phase. It might just be semantics. But I think that the mindset of calling it "endgame" pawn studies, might limit which endgame problems are worth studying, as they would have to be likely practical endgames, neglecting other problems that would stretch the learning of pawn mechanics that could generalize elsewhere.

---
Tags: pawns, pawn-structure
---


title: The London System: Can it be broken?

text:
# Question
Title: The London System: Can it be broken?
I've faced the London System several times so far, and just don't know what strategy to adapt against it (I exclusively play Nf6 in response to 1.d4). I'm a highly tactical player, so I try following up with d5, c5, Qa5, Nc6, Rc8 etc. in order to break open the queen side when possible. But white just plays c3, e3 and curls up into an unbreakable shell. Then I end up getting outplayed positionally because I get frustrated and sac a pawn or two to get some activity.

So, is it possible to play both soundly and aggressively as black, with 1. ...Nf6 against the London System? Is there a way to entice white into doing something reckless? Or does white have complete control over keeping the game boring? What are the main strategic ideas for black (in general, with preference to aggressive options)? Also, I heard that the Colle system has the same reputation as the London system, and they are quite similar strategically as well. Is there a common way to deal with both of these systems?

# Answer
The goal for Black in breaking the London System is to remove White's dark bishop from the game. This is present in almost every losing London System. Hikaru Nakamura plays the London, and makes it very clear he is not willing to trade his dark bishop - even going so far as to play h3 with the sole intention of hiding the bishop on h2.

To break the London, trap / trade the dark bishop.

---

## Warning: This may contain multiple diagrams to display a progression of attacks and also possible positions

*Your Example*

With regards to your exact example,

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 c5 4. e3 Qa5

```

Let me just stop you there. You are down a decent amount in this position, and are looking at dropping a pawn. I understand that you want to get into a game which is not closed, but that is still possible without being hyper aggressive.

*My Suggestion*

Lets get back to where you have a chance to start being aggressive and make a move which is subtly aggressive. I know it may not seem like it, but e6 here is very strong

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 e6

```

*e6, but whhyy*

e6 allows you to begin to exert some control over the dark squares (which are White's weakness as their bishop cannot contest on them). It allows for a responsive aggression. Let us look at a few of the responses available.

...

*4. c4*

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 e6 4. c4 Bb4+

```

Nice, White tried to play into the Queen side and you got in a check (potentially White will trade their dark bishop in defense, but don't count on it). More than this, you gained a tempo, and can castle before White can; all while White's kingside is all locked up.

*4. e3*

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 e6 4. e3 c5

```

White was trying to keep a closed position but this actually results in a torn open one. Now if White defends with 5. c3 Black can begin to really open this up, and hopefully trade off White's dark bishop. 5. c3 Nc6 will open the board up and still be in Black's favor positionally.

**Remove White's dark bishop**

Consider this situation:

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 e6 4. e3 c5 5. c3 Nc6 6. Nbd2 Be7 7. Be2 Nh5

```

White's dark bishop is toast, the game is open, and you have sacrificed neither material nor position. Game on!

Even if you do not choose to be so aggressive here, you have most certainly opened the board up and prevented a closed position.
> 34 votes

# Answer
The London System is ECO D02.

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4

```

I'm liking c5 as it helps you clear some of White's pawns, offers the pawn in a sham-sacrifice sort of way (Qa5+ followed Qxc5) or allows the Bishop to move with tempo (Bxc5, similar to the Queen's Gambit.)

Here's a sample game by Erik Lundin and Hans Ek, from 1963. Doesn't look too awful:

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 c5 4. e3 Qb6 5. Nc3 Bd7 6. dxc5 Qxc5 7. Bd3 e6 8.  O-O Be7 9. Ne5 Bc6 10. a3 Nbd7 11. Ne2 Qb6 12. b4 Nh5 13. Nxf7 Kxf7 14. b5 Bxb5  15. Bxb5 Nxf4 16. Bxd7 Nxe2+ 17. Qxe2 Qc7 18. Ba4 Rhd8 19. Bb3 Kg8 20. Qg4 Qe5  21. a4 Kh8 22. Rad1 Bc5 23. Rd3 Rf8 24. c4 dxc4 25. Bxc4 Rf5 26. Qd1 Bb6 27. g3  Raf8 28. Rb3 Qf6 29. Qe2 Rf3 30. Bd3 Qe5 31. Rb5 Bc5 32. Qb2 Qxb2 33. Rxb2 b6  34. Be4 R3f7 35. Rd1 g6 36. Rd3 a5 37. Kg2 Kg7 38. h4 Re7 39. Rc2 Rff7 40. Bc6  Rf8 41. Rc4 1/2-1/2

```

Black has the option of accepting the poisoned-pawn at move 6 which could be a lot of fun. That's why I chose this variation for you to look at.

**EDIT** \- Why did Ek play `9. ... Bc6` ? I believe that after `10. Nxd7` he didn't want to recapture with the decent Knight on `f6`, he surely didn't want to recapture with his King, and he didn't want the `b` Knight sitting on the passive `d7` square; he wants it on `c6`. The white-squared Bishop is fairly limited so he's willing to trade is for a Knight. With his move, if Lundin captures, he develops his Knight to the `c6` square with tempo.

That being said, Stockfish calculated the following variation with an even game:

```

[fen "rn2k2r/pp1bbppp/4pn2/2qpN3/5B2/2NBP3/PPP2PPP/R2Q1RK1 b kq - 3 9"]

1... O-O 2. Qf3 Nc6 3. a3 Rfc8 4. Qg3 Qb6 5. Rab1 Be8 6. Be2 Qa5 7. Rfe1 a6 8. Red1 Kh8 9. Bd3 Nh5 10. Qh3 g6 11. Nxc6 Bxc6 12. Be5+ Kg8

```

I entered Ek's `9. ... Bc6` and let Stockfish calculate the continuation. There was no substantive difference between the score for this continuation versus what was actually played.

```

[fen "rn2k2r/pp2bppp/2b1pn2/2qpN3/5B2/2NBP3/PPP2PPP/R2Q1RK1 w kq - 4 10"]

1. Ne2 Nbd7 2. Nd4 O-O 3. c3 Nxe5 4. Bxe5 Bd7 5. Qb3 b6 6. Qc2 h6 7. h3 Rfd8 8. Rfd1

```

Finally, I entered the `10. Nxc6` into Stockfish to gain some insights into what would happen had Lundin taken the Bishop. The resulting score was about the same, with a slight improvement for Ek. The moves look very computer-generated; White's response is actually very sharp and seems to be intended to trap Black's Queen. I am betting the position is actually razor sharp; we see that Black's Queen is relocated to the side of the board where nothing is happening. In some variations White's Queen goes to `b3` and, backed up by a Knight and both Bishops, begins an attack which wins material.

```

[fen "rn2k2r/pp2bppp/2N1pn2/2qp4/5B2/2NBP3/PPP2PPP/R2Q1RK1 b kq - 0 10"]

1... Nxc6 2.Bc7 Rc8 3.Na4 Qb4 4.c3 Qg4 5.Be2 Qf5 6.Bg3 O-O 7.Bd3 Qg4 8.Be2 Qf5

```
> 12 votes

# Answer
The weakness is b2 with the absence of the bishop. This is James Rizzitano's recommendation against the London system in his book "How to Beat 1 d4":

```

[FEN ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4 c5 4. e3 Nc6 5. c3 Qb6 6. Qb3 c4 7. Qc2 Bf5

```

The bishop is immune due to the b2 weakness (the rook on a1 will drop).
> 8 votes

# Answer
Look through some games where black wins against the London System. Some of these are won using a King's Indian Defense type setup.
> 6 votes

# Answer
The London system is a system for White where the dark squared bishop is brought out early to f4 after d2-d4. There are several ways in which it can appear:

```

[fen ""]
1. d4 d5 2. Nf3 Nf6 3. Bf4

```

and

```

[fen ""]
1. d4 Nf6 2. Nf3 g6 3. Bf4

```

and

```

[fen ""]
1. d4 Nf6 2. Nf3 e6 3. Bf4

```

This means it is very hard to avoid meeting the London system after White starts with 1.d4.

The question was for a solid and aggressive option for Black after answering d4 with Nf6. One such system is to play it **the King's Indian way**. It is solid in the way that your King is safely tucked away early and it is aggressive as it keeps the options of both c7-c5 and e7-e5 to attack White's centre.

This way is recommended by Boris Avrukh in the new Beating 1.d4 Sidelines.

One of Avrukh's lines goes:

```

[fen ""]
1. d4 Nf6 2. Nf3 g6 3. Bf4 Bg7 4. e3 O-O 5. h3 d6 6. c3 c5 7. Nbd2 Nc6 8. Bc4 cxd4 9. exd4 e5

```

This is one of the more aggressive variations and entails a pawn sacrifice.

Not all variations are this exciting, but in general Black's plan is either to push through e7-e5, often with the help of Qe8, or to play c7-c5 followed by b7-b6 to find a good square for Bc8 on b7, always attacking d4 and White's centre.

Some additional ideas:

* If White plays an early c2-c4 then c7-c5 (and often Qb6) to attack the weaknesses on the dark squares on the Queen side is often good.
* If White plays c3-d4-e3 and sticks his light squared bishop on d3, then the e7-e5 break grows in strength.
* If White avoids an early h2-h3 then Nh5 followed by h6 and g5 to catch the bishop is often worth it, despite the weakening of the King side.
> 6 votes

# Answer
The London is mostly an attempt to play the Slav in reverse. It is very solid and flexible. Black should be careful not to overreach.

Kaufman recommends a King's Indian with a c7-c5 break like Avrukh.

I have had luck with the e7-e5 break from the KID.

A difficult problem for the original question is if your opponent does not play the London, you have to play Gruenfeld, KID, or Benoni.

```

[FEN ""]
1.d4 Nf6 2.Nf3 g6 3.c4

```

For those that do not play with a King's fianchetto, this may not be the best choice. (i.e Nimzo family). It might be best for you to be patient and just go with the Slav in reverse, build up tension on the d4 pawn and queenside pressure with c7-c5, Nb7-c6, Qd8-b6, Ra8-c8, Bc8-d7 while developing and castling on kingside with e7-e6, Bf8-e7, O-O.

One could also close the center with c5-c4 and pawn storm the queenside. If you do, you need to be prepared for his kingside attack, and might want to bring the Be7 back to f8. Look to a well timed e6-e5 break even if it sacrifices a pawn to open the center at the opportune moment.

For instance:

```

[FEN ""]
1.d4 Nf6 2.Nf3 e6 3.Bf4 d5 4.e3 c5 5.c3 Nc6 6.Be2 Be7 7.h3 O-O 8.O-O Qb6

```
> 5 votes

# Answer
One of the benefits of the lines shown by Travis J are the transpositions for helping folks like me who do not play 1. d4 d5. I play the Nimzo-Indian and after 1. d4 Nf6 2. Bf4 e6 I can play the d5 push and be in the systems he mentions.

An even more aggressive option is available with this move order and that's 3. Nf3 c5 to deviate early. Of course, that's great for me but if one is starting 1 d4 d5 that isn't really there.

This leaves a lot of ways to enter the system described by Travis J. I can now simply transpose into the systems he shows.

The move order 1.d4 Nf6 2.Bf4 e6 3.Nf3 c5 isn't better than the other lines he showed and will certainly transpose in many cases but it really cuts down on the options for white.

I haven't played the KID for years and don't particularly like it. So this is a great way to get into an assertive, if not aggressive, response to the London System.

The only real advantage to it is that it really marks the character of the game and it is likely to take white out of the lines to which he's accustomed.
> 3 votes

# Answer
I would recommend looking at games of Eric Prie as white. He plays the London a lot.

http://www.chesspub.com/cgi-bin/yabb2/YaBB.pl?num=1122821205 is a long thread and agood introduction to its issues.

There is an article by Prie, where he outlines the issue with Bf4: http://www.chesspublishing.com/content/8/feb06.htm

However, Nf3 also has the issue of the Qb6, Bf5 lines where white gets a bit tormented. So I do not know how to avoid both :)

The best book I have read is by Cyrus Lakdawala. I find it tricky against the Benoni as I don't like Benoni , despite its reputation at high level. (I am 1800 only)
> 3 votes

# Answer
"Main lines" of the London System (with ...d5) start off with 1. d4 d5; 2. Bf4.

There is an important line to learn when faced with **1. d4 d5; 2. Nf3 Nf6; 3.Bf4** (which of course can arise via transposition: 1. d4 Nf6; 2. Nf3 d5; 3.Bf4). This is inaccurate for white because of the following line:

```

[FEN ""]
1.d4 d5 2. Nf3 Nf6 3. Bf4 c5 4. e3 Nc6 5. c3 Qb6 6. Qb3 c4!

```

Now 7.Qc2 allows 7...Bf5! and Black is at least equal. Sample game

If White plays **7.Qxb6** it is nice for Black; Bc7 can be met either by Ra6 or b5. Black has a ready-made minority attack on the queenside.

White can avoid this whole line with **3. c3** however (Sample game), so Black still needs to learn other plans against the London System. Another possible variation is **6.Qc2!?** which leads to extreme complications.
> 3 votes

# Answer
https://www.youtube.com/watch?v=\_wh5MspHH8A

I play this against the London and have had much success with it. In fact, one of my opponents simply stopped playing the London against me because he never won. As in previous posts, I often find white plays a gruenfeld against me instead of the London, but this has not presented me with any problems as black at all. Check the video about 6 minutes in.
> 2 votes

# Answer
I like this system:

```
[fen ""]

1.d4 Nf6 2.Bf4 d6 3.e3 g6 4.Nf3 Bg7 5.Be2 O-O 6.O-O Nfd7! 7.c4 e5!

```
> 2 votes

# Answer
The Queen's Indian Defense easily equalizes against London, albeit some what passive. The problem with the King's Indian set up is that Black should be ready to play the Pirc if White chooses the so-called 150 attack. 150 attack is a respectable opening used even by super grandmasters like Anand, Kasparov etc. In 150 Attack White normally goes for the King's side attack as in Yugoslav attack against the Sicilian Dragon. Black has to chose an altogether different plan than in KID.

I think the critical test of London is 1. d4 d5 2. Bf4 Nf6 followed by ...c5 , ...Nc6 and ...Qb6 as mentioned herein before. This is one variation which the Londoners (people like myself) abhor to play against.
> 2 votes

# Answer
London system is a little more tricky than it looks like. In many variation, white seems to simply play "normal London move" but there is a lot of knowledge behind those like move order or something else.

As a London system player, i like to play these because there is not a lot of theory compared to other system like Kings-Indian or Grünfeld.

I think that black needs to learn a little bit about the London and which variation to play against a London player. London players seem to prefer a strategical game rather than a tactical game, so they want to play a slow game with small advantages : space.

By the way, there are some tricks on the black side too. For example, playing

`1.d4 d5 2.Nf3 Nf6 3.Bf4`

Is a small mistake on the white side because of the following sequence : `3. ... c5 4.c3 Nc6 5.e3 Qb6 6.Qb3 c4 7.Qc2 Bf5` and here theory says that black simply equalizes and has a little bit more space.

```
r3kb1r/pp2pppp/1qn2n2/3p1b2/2pP1B2/2P1PN2/PPQ2PPP/RN2KB1R w KQkq - 0 1

```

As a London system player, my advice to you is to find a good variation you like vs. the London system but in this case you need to learn a little bit about it. **Play the London System** by Cyrus Lakdawala contains a lot of example and explanation about it, like mentioned before.
> 1 votes

# Answer
There are some very natural easy and wrong ways to play Black against 1. d4 and 2. Nf3 or 2. Bf4. A friend of mine plays those and he continually shows me games where Black loses badly -- even up to FIDE 2600 rating.

As Black he tries to get the Bc8 developed quickly, so 1. d4 d5 2. Nf3 Bf5. I often hit the d4 pawn quickly to encourage e2-e3, so 1. d4 Nf6 2. Nf3 c5 3 e3 and White has to play a standard Colle or perhaps a Stonewall Colle.

A small point to keep in mind about plans to exchange White's dark-square bishop: if you can encourage (or wait for him) to play h2-h3, then when you oppose bishops with ...Bd6 he doesn't have Bf4-g3 since ...Bxg3 fxg3 is horrible for White.
> 1 votes

# Answer
Here is an example of the Steinitz Countergambit against common White responses. Evaluation remains approximately 0.0 for each move. White never gets a chance to get their bishop or knights off of their starting squares or castle by move 10 and has a doubled pawn. The Lichess database says White wins this position 41% of the time, Black 55% of the time, draw 4%.

```

[FEN "r3kbnr/pp3p2/1qn5/3pPbpp/2p5/2P1P1B1/PP3PPP/RNQ1KBNR w KQkq - 0 10"]
1.d4 d5 2. Bf4 c5 3. e3 Nc6 4. c3 Qb6 5. Qb3 c4 6. Qc2 e5 7. dxe5 Bf5 8.Qc1 g5 9. Bg3 h5

```

White's most common next move is 10. h4, in which the evaluation flips to -1.2 (because 10..g4, and then you're controlling more space on the kingside and you're preventing Nf3 and you're going to win a pawn by move 14).
> 1 votes

# Answer
You should counter the London System with 1.d4 g6 2. Nf3 Bg7 3. Bf4 c5 4. dxc5 Bxb2. Or 1. d4 g6 2. Nf3 Bh6 (Reverse Guatemala Defense). Since white usually loses without his dark squared bishop, you should trade it as soon as possible. Another solution is 1. d4 h6 2. Nf3 g5. This prevents white from moving to f4.
> 0 votes

# Answer
Boring?
You dont get to always play a wide open slash and burn tactical game!

Try the dutch defense or the benoni or something else if you dont like the positions in that London variation.

Personally I have excellent results against it. But then it is usually played by weaker players not GMs.
> 0 votes

# Answer
I recommend using the Queen's Indian defense. I posted my own comment, entitled "Battling the London System" I copied and pasted a game between my two computers using the Queens Indian defense against the London system. The program using the Queen's Indian defense won.
> -2 votes

---
Tags: opening, aggressive-play, closed-position, colle-system, london-system
---


title: Does Fide/Elo rating fade over time?

text:
# Question
Title: Does Fide/Elo rating fade over time?
Let's imagine I am a super genius, and I get a ELO ranking of 3000. And then suddenly I stop playing chess, what happens to my rating then over time? Does it slowly decrease by NOT playing?

This is something I was wondering about when re-watching "Queens Gambit".

# Answer
> 7 votes
The current FIDE rules for calculating ratings are given here for standard play and here for rapid and blitz. As you can see your rating only changes when you play. If you stop playing your elo remains fixed. All that happens is that after 2 years of not playing rated chess you are marked as "inactive". When you die there will be some delay but eventually FIDE will remove your name from the rating list.

A good example of this is the profile of Gary Kasparov. You see from this that he is ranked 2nd in the world but 0 in the world for active players because he hasn't played standard chess since 2005.

If you look at his rating chart you see that his standard rating has remained unchanged since he last played in 2005, his rapid rating has remained unchanged since he last played in 2017 and his blitz rating has remained unchanged since he last played in 2022

# Answer
> 0 votes
Your number will not change and you'll still have 3000 as your rating. On the other hand online there is a slight inflation in ratings over time. So, like having a million dollars today, putting it under the mattress, and twenty years later still having a million dollars... but it just isn't the same. You can see inflation coming about for a number of factors but consider that new players join the game all the time and those who lose a lot will drop out after having given points to those who defeat them. They can even delete their account and "start fresh." Over the board, the opposite problem has crept in - deflation! Organizations keep tweaking their rules to try to fight both problems. In short, your number might be meaningless in the future.

---
Tags: rules, fide, rating
---


# Question
Title: Why is Ba4 an inaccuracy here? Why is Bd3 the best move?
I played this game recently as white: https://lichess.org/b7B16RLF/white#18

```
[FEN ""]

1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Be3 Bxe3 6. fxe3 d6 7. d4 Bd7 8. Nc3 O-O 9. Qe2 a6 10. Ba4 h6 11. O-O-O Qe7 12. h3 b5 13. Bb3 Rab8 14. g4 h5 15. g5 Nh7 16. Rdg1 Ra8 17. Nd5 Qd8 18. Qg2 f6 19. gxf6 Nxf6 20. Qxg7# 1-0

```

On move 10 I played Ba4 to protect my Bishop from the attacking a file pawn while continuing to target the black knight on c6. But according to Stockfish, this is an inaccuracy and that the best move is Bd3.

I want to understand why.

# Answer
> 2 votes
If you follow the suggested virtual variants with an engine on, you can see the reason immediately.

If it still goes over your head: Your tactical instincts should scream danger. Your K and Q idle around on the e-file. Black will attack with exd4 and Re8. Now, only the e pawn is in the way of doom, and Black will win it, if necessary by Nxe4 and d5, or with b4, driving away the Nc3, also if necessary, N-a5xb3 (if Bb3 tries to protect d5, Black exchanges the last defender). It's a pretty straightforward case of pins and mobbing the weakest point.

Example variant: 10.Ba4 exd4 11.exd4 Re8 12.Bb3 Na5 13.O-O Bxb3 14.axb3 Nxe4! 15.Nxe4 d5.

In contrast, Bd3 overprotects e4 and gives you time to get your royal stuff out of the line of danger.

---
Tags: analysis, beginner, ruy-lopez
---


title: Why sacrifice the rook?

text:
# Question
Title: Why sacrifice the rook?
```
[Title "White to move"]
[FEN "1r3rk1/1p4bp/p2p1q2/2pPn1p1/B1PnRp2/PPN2P1P/2QB2P1/3R2K1 w - - 5 27"]

```

This is a diagram from the game between Del Rey, Diego and Efimenko, Zahar on the Zalakaros Chess Festival after 26...Nd4. White answered with 27.Rxd4. I don't understand why white needed to sacrifice his rook for the knight in this position.

# Answer
> 2 votes
Well, he has to because there is no other option. The black Knight threatens to capture the white Queen, but also a 'sacrifice' on f3 which will eventually win the white Knight on c3.

```
[Title "White to move"]
[FEN "1r3rk1/1p4bp/p2p1q2/2pPn1p1/B1PnRp2/PPN2P1P/2QB2P1/3R2K1 w - - 5 27"]

1. Qb2? Ndxf3+ 2. gxf3 Nexf3+ 3. Kg2 Nxd2 4. Qxd2 Qxc3

```

This might not even be the best variation for Black. In any case, even after the sacrifice, White is still lost.

# Answer
> -1 votes
I think it's an clearance sacrifice. Because the position is so jammed up,he would have sacrificed it to make it a bit open.

---
Tags: knights, rooks, sacrifice, exchange
---


# Question
Title: What is the average strength level (ELO) in Lichess anonymous?
I occasionally play lichess anonymously to just hang out without having to worry about winning and tarnishing my record, however I am bad at guessing players' elo.

# Answer
My evaluation is that the average opponentthat you will find does NOT have the average elo.

1. **Both in rated and non rated the distribution of games does not match the distribution of players.** I am not sure if the statistics are published but in short you will find that higher level players more often play many games (I guess practice does make perfecton average). And this is even stronger biased in bullet games. One reason is that on the high level playing bullet reduces the number of secret bots they may face. Another reason is that many weaker players are simply unable to reliably complete games reliably before running out of time, even if they are winning on the board. So many of the low ratings will be based on just a few games per month.
2. **The lack of match making drives up the curve.** Given point 1 we would already expect above average opponents. However in rated that would not be much of a problem as you still get reasonable matches towards your own level. However in unrated lower players will find themselves losing a lot, resulting in fewer of them playing.

Last but not least a proof point:

3. I play both 1 min and 5 min games anonymously. **I find myself winning much more often in 5 minutes games than in 1 minute games** and my own difference in plating strength between the two is not enough to explain the difference. I played many games over the years consistently observing this.

**In short**: the average randomly matched bullet game you will play against a person of above average strength, and even more so in anonymous.
> 2 votes

# Answer
Classical: 1550 Rapid: 1475 Blitz: 1475 Bullet: 1475 UltraBullet: 1325
> 1 votes

---
Tags: online-chess, elo, lichess
---


title: where can I find free chess books?

text:
# Question
Title: where can I find free chess books?
I need a website where I can find free chess ebooks? I would like to see a list of free books to download or read online.

# Answer
I find some resources:
> 6 votes

# Answer
ChessUtilities Reader has some 1000+ eBooks for free and Project Gutenberg is also not bad for chess books.
> 2 votes

---
Tags: learning, books, websites, online, recommendations
---


# Question
Title: Difference in chess engine strength for ''high end 64-bit multicore PCs'' vs. ''low end multicore 64-bit PCs''
I use Arena for tournaments between chess engines.

The interesting thing is that in different 64-bit multi-processor computers ranking is slightly different. I was expecting that they should be the same.

Do you have any idea why this happens?

As an example Booot 6.2 64-bit loses most of the games on a low end new PC. However in a stronger PC with newer 'Core i7' CPU it can even have the same score as Stockfish 8 (which most of the time is in top of tables).

# Answer
How many games did you play? Unless your tournament had enough games, your conclusion wasn't statistically significant.

It's common misconception that Stockfish would play better chess than weaker engines in a short computer chess tournament. This is wrong and wrong. Stockfish's higher ELO means it's **expected** to play better chess. Anything could happen in a short match or tournament.

Magnus Carlsen has the highest FIDE ELO, but that doesn't mean he wins everything. He'd lost to Bu in the 2017 World Cup in a **2-games** mini-match, but do you really think Bu is a stronger chess player than the World Champion?
> 2 votes

# Answer
Briefly looking at the source code on https://github.com/booot76/Booot-chess-engine, this engine uses the walltime a lot. Lines like

```
If (game.time<>game.rezerv) and ((MilliSecondsBetween(game.StartTime,now))>(0.7*game.time)) then break;

```

suggests the walltime is not just tracked for verbose output but to make decisions. Presumably, this is to make the engine a good opponent for human players but makes its behaviour depend on CPU speed.
> 0 votes

---
Tags: engines, stockfish, arena
---


# Question
Title: Can you identify the manufacturer or specific design of these chess pieces?
I was wondering if anyone could identify the manufacturer of these chess pieces, or possibly the name of its design (beyond just "Staunton". It's correct I think, but want to know more)

# Answer
> 6 votes
This is beautiful set, and a nice photo. I imagine it is a family heirloom that has gained a nice patina from much use. It looks very much like one of the original sets from the 1800s by Jacques of London and I would go to their website. https://houseofstaunton.com

In the early sets, rather delightfully, the rooks had a small K or Q symbol engraved inside the turret, so that, in the manner of the time, you could write the score as "Kings Rook at the adverse Queens Bishops square, giving Checkmate"

# Answer
> 3 votes
It's design is called Staunton, named after chessmaster Howard Staunton (see here: https://en.wikipedia.org/wiki/Staunton\_chess\_set).

This chess set is the FIDE official recommended one for tournaments.

---
Tags: chessboards, identify-this
---


title: Why is h3 a mistake?

text:
# Question
Title: Why is h3 a mistake?
This is the 12th move of this game I played as white: https://lichess.org/b7B16RLF/white#22

```
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bb5 Nf6 4. d3 Bc5 5. Be3 { C65 Ruy Lopez: Berlin Defense, Kaufmann Variation } Bxe3 6. fxe3 d6 7. d4 Bd7 8. Nc3 O-O 9. Qe2 a6 10. Ba4?! { (0.06 → -0.77) Inaccuracy. Bd3 was best. } (10. Bd3) 10... h6?! { (-0.77 → -0.21) Inaccuracy. exd4 was best. } (10... exd4 11. exd4 Re8 12. Bb3 Na5 13. O-O b5 14. Qd2 b4 15. Nd5 Nxe4 16. Qxb4 c5 17. Qa3) 11. O-O-O Qe7?! { (-0.73 → 0.20) Inaccuracy. b5 was best. } (11... b5 12. Bb3) 12. h3? { (0.20 → -1.24) Mistake. d5 was best. } (12. d5 Nb8) 12... b5 13. Bb3 Rab8?! { (-1.27 → -0.46) Inaccuracy. Na5 was best. } (13... Na5) 14. g4 h5?? { (-0.22 → 3.88) Blunder. Na5 was best. } (14... Na5 15. dxe5 dxe5 16. Rhg1 b4 17. Nd5 Nxd5 18. exd5 e4 19. Nd4 Rb6 20. Kb1 Rd6 21. Bc4) 15. g5 Nh7 16. Rdg1?? { (3.87 → 0.90) Blunder. g6 was best. } (16. g6 Kh8 17. Bxf7 exd4 18. Nd5 Qxe4 19. Ng5 Qh4 20. Nxh7 Rxf7 21. gxf7 Kxh7 22. Rhg1 Bf5) 16... Ra8?? { (0.90 → 4.30) Blunder. g6 was best. } (16... g6) 17. Nd5 Qd8 18. Qg2?? { (4.35 → 1.82) Blunder. g6 was best. } (18. g6 Kh8 19. gxh7 g6 20. Qd2 Rb8 21. dxe5 dxe5 22. Qc3 b4 23. Qd3 Rb5 24. c4 Rc5) 18... f6?? { (1.82 → Mate in 2) Checkmate is now unavoidable. g6 was best. } (18... g6 19. Nf6+ Kh8 20. dxe5 a5 21. Bd5 a4 22. Rd1 Ra6 23. Bxc6 Bxc6 24. Qg3 b4 25. Rh2) 19. gxf6?! { (Mate in 2 → 11.14) Lost forced checkmate sequence. Ne7+ was best. } (19. Ne7+ Kh8 20. Ng6#) 19... Nxf6?! { (11.14 → Mate in 1) Checkmate is now unavoidable. Rf7 was best. } (19... Rf7 20. Ne7+ Kf8 21. Bxf7 Bg4 22. hxg4 Kxf7 23. gxh5 Qxe7 24. Qxg7+ Ke8 25. fxe7 Nxe7 26. dxe5) 20. Qxg7# { White wins by checkmate. } 1-0

```

We had castled opposite site, and I wanted to start an attack on Black's king. Hence the move h3. Stockfish instead wants me to play d5.

What are the dangers of h3 in this case? What's the idea behind d5? Is there a way to play h3 safely in this position?

# Answer
Again, following the virtual lines answers the question: now your bishop is your problem. You castled opposite, but the bishop will be pestered by the upcoming pawn storm and/or exchanged by Na5, creating even more "hooks" in your position which Black can use to rip open lines. (Frankly, I didn't expect the position is already that bad.) In contrast, what you exchange after d5 and Bxd7 can't get attacked. Your own pawn storm is a snail in contrast, Black comes first anyway.
> 3 votes

# Answer
12 d5 would force the Nc6 back because it would get trapped after 12 . . . Na5(Nb4)?? 13 Bxd7 and 14 b4(a3). This gains saveral tempos compared with allowing Black to play b5 and Na5. You can still attack with 14 g4 after playing 12 b5 and 13 Bxd7.
> 1 votes

---
Tags: analysis, beginner, ruy-lopez
---


title: "Brilliant Move" - Chess.com - But Why?

text:
# Question
Title: "Brilliant Move" - Chess.com - But Why?
I was playing a tournament on Chess.com and received a "Brilliant Move" in the post game analysis. I haven't received this before and was curious of the following.

```
[FEN ""]

1. d4 d5 2. c4 e6 3. Nf3 c5 4. Nc3 Nc6 5. g3 dxc4 6. e3 Nf6 7. Bd2 a6 8. Ne5 cxd4 9. Nxc6 bxc6 10. exd4 Rb8 11. Bxc4 Rxb2 12. Bb3 Bb4 13. Qc1 Rxd2 14. Qxd2 Ne4 15. Qd3 Bxc3+ 16. Ke2 Qxd4 17. Rhf1 Bxa1 18. f3 Nc3+ 19. Kd2 Nb1+ 20. Rxb1 Qf2+ 21. Kc1 Bf6 22. Ba4 O-O 23. Bxc6 Rd8 24. Rb8 Qc5+ 25. Qc2 Qg1+ 26. Qd1 Qxd1#

```
* What is considered a "Brilliant Move" ?
* What about the ***12. *Bb4**** move constitutes it being "Brilliant"
    + My logic was to maintain pressure , develop the queen towards the center , trade out a rook when I felt like there was no way I was going to be able to keep it back there. I am quite low ranked (very new to chess outside of the odd game with friends) . I don't see how this is considered a brilliant move as it was just placing pressure , buying little time for future development.

**My Thought Process;**

* 11. **Rxb2** \- Free Pawn remember hearing about Rooks on the 7th , lets give it a crack
* 12. **Bb3** \- That didn't work out so great, rooks trapped in there, lets hope he moves his black bishop to try and take it so I can keep the attacks up and check him.
* 13. **Rxd2** \- Going to lose the rook to the queen, may as well try and capture a minor piece.
* 14. **Ne4** \- Maintain Pressure on the Queen , can't take my knight without losing his queen, can probably capture his knight put a check in, *when in doubt check it out.*

Literally nothing about that felt "Brilliant" anyone able to assist with why it was perceived to be good?

# Answer
To be honest, brilliant seems like an overstatement for a fairly obvious move. But to answer your question, I think the "brilliancy" is that you actually found the only way to not only save your rook, but even end up winning material.

The point is that after 12..Bb4 there is the threat of 13..Rxd2 after which Ne4 will win the knight on c3.

The only moves stopping black from executing this threat consist of defending the e4 square by playing 13.f3 for example. But then you play 13..Qxd4 after which the c3 knight is under attack. Note that this is the difference between this situation and the situation in which you played Qxd4 right away.

After 13..Qxd4 the knight has to be defended by 14.Rc1. Now black simply castles to bring the other rook into play and there is nothing white can do because of the awkward positioning of its pieces.

Instead of 13.f3 white could also play 13.Bc2 to defend the e4 square, but in that case 13..Qxd4 is crushing as well.

To summarize: I wouldn't say it's a brilliant move (11..Rxb2 would be a more serious candidate as this move requires black to have found the idea of 12..Bb4 and everything after already), but it's definitely strong.
> 8 votes

# Answer
Engines are far better at spotting mistakes than at recognizing "brilliancies". You made a move that is much better than all the alternatives which isn't something obvious like a recapture or a fork in one move, so that's probably what the engine identified as "brilliant". Just don't pay too much attention to it and congratulations for this beautiful win!
> 10 votes

# Answer
## What is considered a "Brilliant Move" ?

Whenever you move, the computer compares your move to all the moves that are possible. If you made the same decision as the computer would have, you made the **best move**. However, the computer also examines these moves retroactively. If your move ends up giving you better position than you would have if you made the "best move", it is reclassified as **brilliant**.

I believe this is all in relation to the level you set the computer to. A low level computer obviously considers more moves brilliant than the highest setting.
> 4 votes

# Answer
The 'brilliant move' indication shows that the engine has missed out on some move, and would not have found this. So you had a general approach that the engine could not evaluate. So consequently, it was evaluated as a brilliant move.
> 1 votes

# Answer
it is simply a novelty that improves your evaluation. It may also be considered brilliant from your level of chess, as it is a multiple move sequence that wins material.
> 0 votes

---
Tags: analysis
---


# Question
Title: In a completely lost position do chess engines attempt to bait their opponent into mistakes, or just play for the longest survival?
Essentially, do Chess Engines acknowledge that their opponents might make "flawed" moves? Or do they always assume absolutely perfect play.

More specifically, if an engine has a choice between 2 moves and one of them is:

* Mate in 5, with perfect play, all of which is completely obvious

and the other is

* Mate in 4 ... but only if the opponent does something superficially counter-intuitive. And if they do the superficially obvious thing then you can actually escape the Mating sequence into a not-directly Mated position

If you assume perfect play, then both positions are a loss, and I assume that engines are "taught" to pick the longest game if all games are lost.

But I would argue that if you believe the game is lost either way, you might want to pick the line with highest chance of an error, instead?

Do engines do that?

# Answer
Chess engines always consider the "best move" possible for both side. What the "best move" means, is the best move found from the engine according to its evaluation function, selection algorithms, pruning and so on. But no, they don't have a sense of "possible error". Because engine evluated a checkmated position with a score plus the distance-to-mate, every engine choose the move that leads to the longest line possible to be checkmated as it will have the highest score found. Assuming no bugs in the engine, of course.
> 5 votes

---
Tags: engines, endgame
---


# Question
Title: How to determine if a position is open or closed in a "rigorous" fashion?
I am creating a set of chess positions to be used \[as a data set\] **for a project**. It's based on *supervised machine learning*, but I need to have labeled data (see more *italicized* text below) before any machine learning can be done. I wish to label each position as open or closed or possibly some combination of the two.

I started out with assigning each position to just "open" or "closed," but this wasn't clear for a lot of the positions. Then I decided to go with a third label, semi-open/semi-closed, which is like the middle and in between open and closed. I’ve labeled most of the positions, but there are many positions that I still haven’t comfortably labeled with a distinct class.

I know that open positions are characterized as having pawnless ranks, files, and diagonals, while closed positions have them clogged up with pawns. In open positions you can usually centralize your pieces, while closed positions give you a hard time moving an arbitrary piece to a random location on the board. There are many other related patterns, features, and qualities.

I can easily go with my **gut feeling** when assigning "closed" to a position that has 7 pawns on each side with each pawn blockading another, and "open" to a position that has pawns only on the flanks and in their starting squares. However, it's hard for me to classify some positions such as these two examples:

```
[White "Position1"]
[Black "Open/Semi/Closed/Etc"]
[FEN "8/5Qpk/p6p/P1b5/4pPn1/2Pp3P/1P1BbqP1/R3R2K w - - 0 1 "]

```

---

```
[White "Position2"]
[Black "Open/Semi/Closed/Etc"]
[FEN "3r1rk1/pp2pp1p/2p3pb/2P5/4P3/4nNPb/PP2P2P/R1RNK2B w - - 0 1 "]

```

What would you assign to the examples above **and why**? For example: one position is more open than the other due to characteristic XYZ, or the second position should not be considered closed since there's an open file, and so on.

Should I just ditch the whole binary-ish labeling (*classification*) and instead assign a variable number (*regression*) describing how open or closed a position is (e.g. 0% to 100% open?) Or is there still a way for positions to go into a few categories, which means that we can have **"rigorous" definitions** of the categories of openness? And "rigorous" as in having few contradictions and preferably can be applied by a human without too much difficulty.

# Answer
> 9 votes
As a chess player who currently studies computer science, I found this question very interesting so here's my thoughts on the topic. You already know how chess books categorize open and closed positions and you may also know that a semi-closed position is one with some of the characteristics of an open but not all. As you understand this makes the line between closed and semi closed positions not easy to be seen. So my recommendation is to use a number to describe the "openness" of a position(although 50% may be a problem). Now some things I thinks you might find useful for implementing you machine learning algorithm. Firstly, I will suggest you to take a look at this article https://chess24.com/en/read/news/how-do-chess-engines-think in the section about position evaluation. Now, some parameters you might use:

1. Number of pawns(a position with no pawns is apparently wide open).
2. Number of pawn moves(assuming a position with three pawns each,there's a big difference if they are on f2,g2,f7 and f7,g7,h7 respectively and if they are on c4,d5,e4 and c5,d6,e5.
3. As you see in 2 you may give an extra weight for pawn moves in the center. Generally it will be a good idea to give extra weight for anything open in the center. This will be more clear in 4.
4. Number of open and semi-open files. The ones in the center again should have an extra weight.
5. Open diagonals. Note that diagonals with one or more isolani should be counted almost as opens(As an example think about the Indian's bishop targeting d4 and b2 when the c pawn is not on c3). And you should of course take into consideration the length of the diagonal.

Note that essentially you don't judge the whole position, just the pawn structure. That's why count the available moves of every piece is a mistake. This just measures the mobility of the given piece and doesn't necessarily has something to do with the pawn structure. For example, in a position with no pawns a Knight on a1 has only two moves while in a closed King's Indian the f3 Knight has seven( only one is occupied by the King). Some of them drop the piece but they are legal moves nonetheless.

Hope that helps a bit!

# Answer
> 3 votes
In the end the distinction between open/closed position is subjective and as you noticed there will always be some overlap or positions that don't fit perfectly into either category.

What exactly do you need this for?

For me the typical closed position has blocked pawn chains, generally many pawns, few or no open files. Because of this, the play tends to be slow, positional. Typical plans include undermining the pawn chains from the side or pawn storms/attacks against the enemy king.

Conversely open position have fewer and mobile pawns, open files, more space for pieces and are generally more tactical.

# Answer
> 2 votes
I echo user 1583209; why are you doing this?

But just as an abstract exercise, how about this measure of open-ness?

Look at every piece on the board, and count the number of moves that it would have if there was nothing else on the board. Add this up for all pieces on both sides and call it $N\_{empty}$.

Now count the number of moves/captures that each piece actually has and add these. Call this total $N\_{actual}$. The ratio $N\_{actual}/N\_{empty}$ is a measure of the open-ness of the position.

I think this is cute, and maybe as good as anything else, but why are we doing this?

# Answer
> 1 votes
As in openings, positions would be regarded as closed or open depending on whether they were blocked by pawns or not. And as in the openings, these could be semi-open as well, which as you indicate would be an in-between type of situation. These distinctions are not necessarily fixed but can change depending on whether or not pawn exchanges are made to open up the position. In an open position, the pieces would have more freedom to roam and search for tactical combinations as opposed to a closed one where the opposing pieces couldn't come in contact right away and more maneuvering would take place behind the lines. I would think that it would be more reasonable in your classifications to stick to these more general categories than to try to use percentages to describe what will be more or less fluid situations. I would categorize both of the positions shown as semi-open since Black has more open lines of attack and freedom of movement for his pieces in both as opposed to White. In fact, if it's Black's move, he has a pretty forced mate in position number 1 with **1..., Qxg2+!; 2. Kxg2, Bf3+; 3. Kf1** (if 3. Kg3, Bf2#) **Nh2#**. And if Black moves first in position number 2, he forces mate with **1..., Rxd1+!; 2. Rxd1** (if 2. Kf2, Be3#)**,** **Nc2+; 3. Kf2 Be3#.**

# Answer
> 1 votes
You cannot. They all have characteristics of open/closed between the two extremes so constitute a fuzzy type of set or a statistical sort of categorization. There is no way to declare absolute that a position is either open or closed when many (most?) are in the vague area of semiclosed/semiopen as nobody tries to define quarter or 3/4 closed/open or finer fractional/decimal categories.

# Answer
> 0 votes
If i had to create a generalization it'd be something like, when you have atleast two central pawns for each side and they are in contact with each other and can't be taken (say pawns on d4 e5 and e6 d5) that is a closed position. Positions ranging from there being 4 central pawns that are not in contact (e2 d3 and e6 d5 for example), to there being 2 central pawns (1 pawn for each side, like pawns on d4 and d6, or pawns on e4 and e5) are differing degrees of being semi closed. Positions with only 1 central pawn, or no central pawns on the board, I would consider open.

# Answer
> 0 votes
There are historical notions that made more sense at some point of history than now, when the whole chess community knowledge that can sit in books or other storage media, I think also online databases, has been substantially exploding as well as the number of players globally, and means to diffuse that knowledge. Some talk about holes in the chess theory. I think some thinking in the line of extending notions and adjusting them to how big chess could be that we might not have foreseen as a community in the past, could help make more automatable or useful metrics that would have value for any legal position, and what such metric might associate to odds given some 2 player pair of average "strength" for the full legal chess point of view with all players quality of move possible. Simpler version would be like the endgame table assumptions, for all legal positions giving its output under the assumption of perfect continuation.

But, even if now one can find many ways to dismiss such dichotomies for not being applicable to all positions, a good way to adjust that past intuition made feature, is to see it as the opposite bounds of some more, how can I say, fine grain notions of line mobility obstacle degree. I could see many ways to test or construct automatic metric, that would compound all line pieces immediate mobilities and potential. That last word, is to tie in to what should be kept on the open-closed dichotomy. That opening pawn moves might set the tone, are irreversible, and their mutual, relative and across the board configuration tend to change slowly, so that having had the spectacular version of either open (that we would all agree it is), or closed, would soon steer the gamut of plans left possible and plausible as winning plans.

One could call the various constructed quantitative functions of the full position information metrics measuring each properties.. it is even possible that the notions would behaver as a good feature in ML on the data analysis side, if it started very fine grain, defined for each line pieces specific placements given all the other pawn placements (why not also include other blocking material of own color, and opposite color soft occlusion.

In fact, it might be equivalent to just the basic input vector for Lc0. Which is directly and exactly encoding the mobility rules set.

That would be the full multidimension version of what closed and open might mean as an average yes or no criterion over all those ultimate fine grain mobilities for the line pieces. There might also be another angle that would not be about the immediate mobility. But that would need a better formalism to describe many possible future mobilities for fast pieces given slower evolution of the slower pawn structure. This is not a good answer. I am just pushing the notion to their limit. Not dismissing them. The "gut feeling" might actually be an internal wet implementation, of what you could simulate in such ML project. I like to think. Good question, good principle of question for chess theory elements, actually. But I would not reject notions that can't be automatize directly, and would rather extend the notion to the now available data from actual machine players too. That which start by exploring legal chess, might have more dynamic range for your type of project. I suggest also digging in its latent space entrails. If you can do that.

# Answer
> 0 votes
As a statistician with a PhD in psychometrics and an interest in chess, I find this fascinating.

I would not categorize the variable. Three levels is better than two but why have levels at all? You can give an openness rating from 0 to 100.

One way would be to have a bunch of good players (whoever you could get, or pay) to rate a bunch of positions on how open they are. Then you can look at various features (many suggested above) and do a regression.

Alternatively, you could just make up a formula intuitively.

# Answer
> 0 votes
The best way to classify the position would be not just "closed" or "open", but with a continuous scale. I would propose having a "completely" closed position at zero on the scale; it's much easier to define the most closed possible position (a KP endgame with 16 pawns total and no pieces) than the most open position which seems basically impossible to define rigorously.

Several factors should be taken into account when considering how closed a position is, the most important of those being number of pawns, pawn mobility, and then piece mobility (but weighted specially). There are also several other slightly less important things, such as how exactly to weight mobility (more on that later) and open/semi-open files.

Assuming the position with zero for a maximally closed position, we can first take (8 - number of white pawns) and (8 - number of black pawns), then raise them each to the power of some constant (likely between 1 and 1.5, say 1.4 for the sake of demonstrating the next concept), then add those together. We have the exponentiation to make a position with 8p4p more open than a 6p6p position, and also to make the difference in openness between 4p4p and 6p6p be greater than the difference between a 6p6p and 8p8p position.

The next thing to take into account is pawn mobility. Pawn captures, including en-passant, should be weighted to be more significant than just single pawn pushes, and double pawn pushes should be weighted to be pretty insignificant since being able to double push on top of the single push should not give that much more openness.

Based on the scale from the previous part where the maximum openness score is around 36, every single pawn push should be weighted at around 1, every double pawn push should be weighted at around 0.5, and every capture should be weighted around 1.5. An additional bonus between 0.5 and 1 should probably be added to moves by pawns on the c, d, e, or f files, that way the center being locked makes the position significantly more closed.

There's also the matter of mobility. In my opinion, non-pawn mobility should be weighted by piece type and the square that's being moved to. For example, the king should have no weight in terms of mobility and the queen should have little weight so the queen doesn't skew the openness of the position too much. This might be unnecessary however.

The main point in mobility is weighting the moves based on the pawns on the file that they move to. If the move goes to a square in any of the spaces in front of a friendly pawn on the move's file, an openness score of around 0.3 can be added. Note that if there is no friendly pawn then no score is added. Additionally, if the move goes to a square behind an enemy pawn on the file, an additional bonus of roughly 0.3 should be added.

I think this answer is already too long, so I won't talk about open files. Also note that I haven't really tested out these ideas, and I suspect that the mobility stuff should be done differently so endgames don't automatically get scored as more closed due to the decreased total pieces and hence decreased overall mobility. This can probably be done but I can't figure out how to do it easily without breaking the idea about zero on the scale.

---
Tags: evaluation, terminology, mathematics, closed-position
---


title: Is the following position a fortress?

text:
# Question
Title: Is the following position a fortress?
```
[FEN "8/4k2p/p1b1p1pP/Pp1p2K1/1PpP1P2/2P1R3/8/8 b - - 0 1"]

```

Houdini6.02 eval flatlines at 1.37, but I reached d= 54 , and , although the eval continued to flatline, the main line indicated White pushed the f4 pawn in f5 toward the end. I started a trial with the pawn already in f5 , Black to move, and White won. Still I am not sure because Houdini 6.02 could have missed a possible defense against the f5 push. Can Black defend against the f5 push without deteriorating the position ( maybe allowing the White rook to penetrate its position)? Or the position is a win for White , albeit slowly? Just for curiosity , if the verdict is draw , can White win in absence of the 50 move rule?

# Answer
The key to tackling these kind of positions in a game is to imagine where you would like to put your pieces and then see how you could achieve that.

In this position for white the first aim would be to get the king to e5 to attack the e6 weakness and at the same time threaten to infiltrate on either f6 or d6. The problem is that black will have no problem defending the e6 weakness and defending the infiltration by keeping the king on e7 meanwhile shuffling the bishop.

Another weakness will be required to make progress. As it happens there is also no way of getting the king to e5 while the f pawn is on f4 so any plan will have to start with sacrificing the f4 pawn.

If it were white to move then the immediate f5 would force open the g file, a second weakness. Black would have to accept the sacrifice and ef would expose the black king to check from the rook so gf is forced. Then there is no way for black to both prevent the rook penetrating on the g file and prevent the king from infiltrating via f6 or d6. One line could go like this:

```
[fen "8/4k2p/p1b1p1pP/Pp1p2K1/1PpP1P2/2P1R3/8/8 w - - 0 1"]

1. f5 gxf5 2. Kf4 Be8 (2...Kf6 3. Rg3 {and black can't prevent the rook coming to g7 next move}) 3. Rg3 Bg6 4. Ke5 {Black is in zugzwang. Either the white rook is going to penetrate on the g file or the king is going to infiltrate on f6 or d6}

```

So, black's first task is to stop this simple plan. The only way to do that is with Kf7 which unpins the e pawn and allows the recapture ef. The problem for white with this is that it gets rid of the weak e6 pawn and replaces it with a weak d5 pawn.

The now open e file is nothing like as good as the open g file because of the white pawn on h6. The only way for black to defend an open g file is to block the file with the bishop on g6 but for the open e file all black needs to do is to cover the entry squares of e6, e7, e8 which can be done either by the king on f7 or a combination of the king on f6 and the bishop on c6. The weak d5 pawn can be protected by the bishop on either c6 or b7 and the white king can be prevented from infiltrating via e5 by the black king on f6.

If white could both threaten to infiltrate with the king to e5 and threaten to take the d5 pawn with the rook then a zugzwang could be possible but unfortunately the only way for the rook to threaten the d5 pawn is from e5 and if the rook is on e5 then the white king can't go to e5. Hence this position is a fortress.

This is what the lines would look like:

```
[fen "8/4k2p/p1b1p1pP/Pp1p2K1/1PpP1P2/2P1R3/8/8 b - - 0 1"]

1...Kf7 2. f5 exf5 3. Re5 Bb7 4. Kf4 (4. Re1 Bc6 5. Re2 Bd7 6. Kf4 Kf6) Bc6 5. Re1 Kf6 6. Re2 Bd7 7. Re5 Bc6

```

Going back to the initial position is there anything white can do to prepare the f5 push to make it work? Or, to put it another way, what must black do to stop f5 from working. The answer is that black must keep the king on f7, ready to both defend the e file if it opens and to play kf6 if white threatens to play Ke5. At the same time black's bishop must defend the d5 pawn from either c6 or b7 whenever the white rook is on e5 and it must defend the e8 entry square from d7 or c6 whenever the rook is not on e5.
> 4 votes

# Answer
Definitely not a draw. Use zugzwang to invade with your king on the dark squares(since the bishop can only guard light squares)All you have to do is use the following sequence.

```

[FEN "8/4k2p/p1b1p1pP/Pp1p2K1/1PpP1P2/2P1R3/8/8 w - - 0 1"]

1. f5 gxf5 2. Re5 Bd7 3. Re1 Be8 4. Kf4 Bh5 5. Ke5 Bf3 6. Rg1 Bg4 7. Rg3 Kf7 8.
Kd6 Kf6 9. Kc6 e5 10. dxe5+ Kxe5 11. Re3+ Kf6 12. Kxd5 f4 13. Re8 f3 14. Kd4 Kf7
15. Re4 Bh5 16. Rf4+ Ke7 17. Kc5 Kd7 18. Kb6 Kd6 19. Kxa6 Ke5 20. Rf8 Bg4 21.
Rxf3! Bxf3 22. Kxb5 Ke4 23. Kxc4 Ke5 24. Kc5 Ke4 25. c4 Ke5 26. b5 Ke6 27. Kb6
Bd1 28. a6 Bf3 29. a7 Ke5 30. c5 Ba8 31. Kc7 Kd4 32. Kb8 Bh1 33. b6 Kxc5 34. b7
Kd4 35. a8=Q Bf3 36. Kc8 Be2 37. Qa5 Bg4+ 38. Kd8 Kd3 39. b8=Q Ke4 40. Qb7+ Kf4
41. Qxh7 Bd7 42. Qg7 Bb5 43. h7 Ke4 44. h8=Q Kf4 45. Qh4+ Ke3 46. Qgg3+ Ke2 47.
Qxb5+ Kd1 48. Qb1+ Ke2 49. Qhe4+ Kd2 50. Qgd3# 1-0

All you have to do is use the following sequence.

```
> -1 votes

# Answer
I tried again with Houdini 6.02 Pro for One hour ( depth 58/97) and again , starting from a criticala point , one quarter of and hour again ( depth 55/92). On the thitd iteration the win was evidentv, although in some defensive lines slightly more than 50 moves were necessari. The questione however was not Is the position above a draw with perfect play under FIDE rules , but Is the position above a fortress , which clearly Is not , since Black position can be broken even with perfect defence.
> -1 votes

---
Tags: analysis, endgame, fortress
---


# Question
Title: Are Elo ratings comparable across history?
It is fun to speculate how the great players of today would fare against those of the past.

With the advance in knowledge of the openings, particularly aided by computers, a leading modern player would have a great advantage against one from history. Probably, Carlsen would have Morphy, Capablanca, or Fisher (playing at their respective peaks) trussed up like a roasting turkey by move 15 or 20, simply because of his opening expertise. For this reason, one would expect the Elo ratings of modern top players to exceed those of their historic peers.

In one way, the comparison seems unfair. If modern experts played those from history, starting from a dynamic post-opening position with approximately equal fighting chances for both sides (as judged by a computer), who would win then? Would this be accurately reflected in the comparative Elo ratings? If so, this would go with top Elo ratings being restrained from a general upward drift.

# Answer
> 7 votes
Statistician and ratings expert Jeff Sonas writes

> "\[A\] rating always indicates the level of dominance of a particular player against contemporary peers; it says nothing about whether the player is stronger/weaker in their actual technical chess skill than a player far removed from them in time. So while we cannot say that Bobby Fischer in the early 1970's or Jose Capablanca in the early 1920's were the "strongest" players of all time, we can say with a certain amount of confidence that they were the two most dominant players of all time. That is the extent of what these ratings can tell us." (source)

His own project Chessmetrics attempted to estimate playing strength across history for various players (see site overview).

Sonas uses a "*a weighted and padded simultaneous performance rating*" to enable comparisons across eras.

There are challenges but Sonas discusses this in some detail during his 15 Aug 2023 interview on the *Perpetual Chess Podcast* (ep. 343).

<sub> Related: The Historical Comparison of Players </sub>

# Answer
> 3 votes
I am not a statistician, so I can't speak to the accuracy of ELO ratings across time, but as a historian, I would say that comparing players from different eras is ultimately a flawed (if fun) project because they are acting with the specific knowledge of their time period and playing with the goals of people of their time.

Given a dynamic, post-opening position, contemporary elite players would almost always beat past elite players. This is because they would know more endings, have a larger knowledge base of known positions and how to play them, and understand how middlegame positions work better (i.e. the benefits of advancing of a and h pawns are only recently really understood).

For example, Morphy would be brilliant, but he would be looking for Morphy-like combinations while Capablanca or Karpov would be looking to restrict those possibilities with solid positional play. Morphy would probably react poorly because the elements of positional play (as we understand it) had not even been articulated yet.

Different elite GMs and champions have different goals. Anderssen to create works of beauty, Tarrasch to articulate sound principles of play, Fischer to crush his opponents, etc. It's hard to measure this if the players' goals and motivations are totally different.

This doesn't even bring up the question of time control, which has not been standard throughout history. Like, how would Botvinnik do without having recourse to adjournments?

The idea of chessmetrics to try to determine a player's relative strength to his contemporaries is a good method to understand some aspects of player strength, but it is not as solid when comparing people across time, as Morphy and Philidor, for example, did not have access to really strong competition.

One would really wonder what would happen if Morphy or Lasker or Keres had access to chess theory today, but that is another question...

---
Tags: history, elo
---


title: Viability of 4 player chess engines

text:
# Question
Title: Viability of 4 player chess engines
I got into a discussion with a friend recently about the viability of 4 player chess engines. He claimed that they would be impossible to create at anywhere near the level of modern chess engines.

I'm by no means an expert on engines, but I do understand some of the concepts behind them to a degree. Here's my take, and I'd appreciate some more knowledgeable input on where my logic is wrong.

Taking an average branching factor of 35 in normal chess, I'll give 4 player a branching factor on average of 130. I reached this by taking the normal average of 35, and adding the maximum number of extra moves outside the usual 64 square board from bishops, rooks, and queens, resulting in 107. Then you'd need extra headroom for the other pieces, because even if they can't take advantage of the extra squares, there is generally more open space on the board in this variation, allowing for more legal moves. However, the number that should be used for that is kinda tricky for me to figure out, so I've taken a guess with an extra 23 moves to round it to 130.

For a branching factor of 130, you get similar number of positions after 18 moves as a branching factor of 35 after 24.65 moves (about 112 undecillian), this will be brought up again later. This was reached by using log(35, 130^18).

With regards to pruning, in my opinion it would be far more effective in four player chess, as an increased number of pieces that can attack you means there are far more effective strategies against you, and far more moves you can make would result in very low evaluation. I'm not sure how having four players would impact the search tree though, as alpha beta pruning uses an adversarial search tree, but I'm not going to worry about that too much.

Modern engines certainly have the capabilities to calculate forward 25 moves with pruning, and as I think the pruning factor would be increased in 4 player chess, I believe looking forward 18 moves with pruning is certainly feasible.

I realise this is all a massive approximation and my logic may be completely wrong on many counts, but what are your thoughts on the viability of effective 4 player chess engines?

As a side note, I'm aware that this question may be toeing the line with subjectivity rules, but I do think it should provide technical and theoretical insight on the nature of engines from those more experienced in them, which aids in the site's goal of learning. As such though, please include justifications in answers like how I've done in my post to avoid purely opinion based discussion.

# Answer
Which version of four-player chess are you interested in? There's some discussion at the Wikipedia page for four-player chess. A key question is whether or not it's effectively a two-player game (e.g. with each pair of players opposite each other playing for the same team).

If it's a game between two teams, I don't see any obstacle to developing a strong engine (given sufficient time and resources) - it has been done for many chess variants and other games.

For a game involving more than two independent players, everything immediately becomes much more murky. For multi-player games, it can be very hard to define what is an optimal strategy, or the value of a position, or anything like that. You would often be in a position where *none* of the players has a way of guaranteeing not to lose - if any one player is ganged up on by all the others, that player is at a severe disadvantage. Sometimes it's possible to define a scoring method in such a way that the notion of an optimal strategy still exists, but (unlike in a two-player game) you can be disadvantaged by an opponent deviating from the optimal strategy.
> 1 votes

---
Tags: engines, chess-variants
---


# Question
Title: Today's engines changing what was considered the best plan
So when I peruse the many strategy books I have, I have found many positions where there is a clear best plan, that seems clearly much better than all other plans. The variations given by the experts, and the game continuations seem to confirm that the stated best plan is truly the best. But now with 4000+ rated engines, the best plan that, say Stockfish, finds is at odds with those experts' opinions with some of these positions. Before simply concluding that these engines, despite their ratings, simply don't understand these positions, I looked carefully at their analysis, and indeed there are moves by the opponent, not necessarily tactical and some pretty deep down the tree, that the experts did not mention, and the best lines of play found by the engines seem to suggest that the "best plan" does not turn out to be as good as the experts say after the apparent best lines of play found by the engines. But without calculating any variations, the quoted best plan does seem to make the most sense, meeting the strategic needs of the position. But the engines analysis change that outlook. So what does this mean for the meaningfulness of these quoted best plans?

# Answer
This is a tricky thing to answer. What is boils down to is the following:

On a game theoretical level there is no such thing as a plan. There are no such concepts like "strategical advantages", doubled pawns being bad, the bishop pair being good and so forth. There is just calculation. A position is a win, a draw or a loss based on the concrete variations that happen with best play.

However, for a human that is not very useful. No human, in fact not even any engine can get anywhere close to solving chess and/or calculating trillions of variations. This is where especially traditional engine development and human play diverge:

For humans it turns out that beside developing an intuition for positions, some general guidelines can be helpful. The bishop pair being better than two knights may not be true in every position, however, it turns out to be true in many if not most positions. And so, due to not being able to calculate trillions of variations, for humans those general guidelines are a more practical approach that *often* works well. That being said, especially very strong players will also at times break those guidelines when they feel like in the position at hand the guideline does not work well.

On the other hand you have engines. While they can not calculate trillions of variations either, they can by now calculate at least millions per second and even many decades ago already calculated thousands of variations per second, more than any human could do. With this calculation power it can become feasible to attempt to go through many concrete variations. Engines will still need heuristics similar to those used by humans, however, with the much more powerful search, concrete calculation will always overturn the general guideline if it has to. With new neural network engines their mode of operation has changed a bit, however, they just the same will always have calculation overturn general guidelines if need be.

When looking at general plans in openings the same is necessarily the case: the human approach is to find something (a plan), that works most of the time and is practical to use. Meanwhile the engine will use brute force calculation to figure out that actually, if the opponent plays in just the right way, the plan will not work and thus a different sequence of moves is preferable. However, while this is correct from an objective point of view, it may not be practical for a human. So the good old simple plan in an opening might still be a humans best bet, even if the engine rightly points out that things are more complicated than that.

That being said, there are also some variations where entirely new plans have been found by engines. (to give one example, since engines became really strong some 2 decades ago, we see a lot more h pawn advances in top level chess)

So I suppose my bottom line is: For a human such plans are still useful in practical play, even though they will not always work.
> 3 votes

---
Tags: engines, strategy
---


# Question
Title: My engine's alpha-beta search returns negative score eval. on odd depths and positive on even. Dont understand what is causing this bug
I've been working on implementing/improving my engine's search function the past few days, but yesterday I decided my current search implementation was a mess and that it would be much better to rewrite it from scratch, which is what I'm currently doing.

The issue is, my alpha beta function is returning negative/positive evaluations for the same position for even/odd depths. To try and debug, I wrote a barebones search using the chess programming wiki as reference, but the issue still persists. I don't see where the issue is/could be.

Here is my current implementation:

```
static int quiesce(Board *board, int alpha, int beta, int color) {
    moveList mList = { 0 };
    moveList tacticalMoves = { 0 };

    int nMoves    = genLegalMoves(board, &mList);
    int nTactical = genLegalTactical(board, &tacticalMoves);

    int standPat = eval(board, nMoves, color);
    if (standPat >= beta)
        return beta;
    if (standPat > alpha)
        alpha = standPat;

    for (int i = 0; i < nMoves; i++) {
        if (nTactical == 0) break;
        make(board, mList.moves[i].move);
        int score = -quiesce(board, -beta, -alpha, -color);
        unmake(board, mList.moves[i].move);

        if (score >= beta) return beta;
        if (score > alpha) alpha = score;
    }

  return alpha;
}

int alphaBeta(Board *board, int alpha, int beta, int depthLeft, int color) {
    if (depthLeft == 0) return quiesce(board, alpha, beta, color);

    moveList mList = {0};
    genLegalMoves(board, &mList);

    for (int i = 0; i < mList.nMoves; i++) {
        make(board, mList.moves[i].move);
        int score = -alphaBeta(board, -beta, -alpha, depthLeft - 1, -color);
        unmake(board, mList.moves[i].move);

        if (score >= beta) return beta;
        if (score > alpha) alpha = score;
    }

    return alpha;
}

void search(Board *board, int depth) {
    moveList mList = { 0 };
    genLegalMoves(board, &mList);

    int best;
    int max = -500000;
    for (int i = 0; i < mList.nMoves; i++) {
        int color = (board->turn == WHITE) ? 1 : -1;
        make(board, mList.moves[i].move);
        int score = -alphaBeta(board, -500000, 500000, depth - 1, -color);
        unmake(board, mList.moves[i].move);

        if (score > max) {
            max = score;
            best = mList.moves[i].move;
        }
    }

    printf("score: %d, best move: ", max);
    print_move(best);
    printf("\n");
}

```

I suspect the issue is the quiescence function, as I don't quite understand how it's supposed to be implemented, but I don't see any glaring differences from the chess programming wiki's pseudocode that would cause this behavior.

# Answer
In the evaluation function, you need to flip the eval if it is black to move
> 2 votes

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Tags: engines, programming
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# Question
Title: Where can I play chess online without extra rules?
I tried both chess.com and lichess but both have their own made up rules that are not common and I don't want to play by them, namely the auto-resign.

I never want to be auto-resigned when I have time left and I do not want my partner to be auto-resigned and preventing me from winning. In addition, I do not want my partner to get indications on which opening is played and the quality of moves as happens on chess.com in live games.

I signed up to chess24 but it seems they no longer offer online play.

# Answer
The rule you refer to appears to be the forfeit resulting from when a game is ‘abandoned’ for a period of 60 seconds or more. This is necessary for the smooth running of an online site with innumerable time limited games.

However, all is not lost and there may be a way out of your percieved predicament !

You and your friend could choose a long duration of play with for example one day per move: which allows you to play no less than a move a day- allowing you to play faster than this rate at your own pace and not risk forfeit from “abandoning" a game. Alternatively, another chess online play site: the Internet chess club (icc.com) has the option to add time to your opponent’s clock if you might wish.
> 4 votes

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Tags: lichess, chess.com
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# Question
Title: Where can I find past Titled Tuesday data
I'm hoping to create a dataset with Chess.com Titled Tuesday results. I have found this link which has the tournaments https://www.chess.com/tournament/live/titled-tuesdays?&page=7 but for some reason, the list won't show anything past Page 7.
I was wondering if there is already a dataset like this. Or even getting access to the tournaments should be fine. I tried with Wayback Machine as well but no luck. I'm hoping to collect data starting from the first Titled Tuesday ( started 2014 I believe)

# Answer
> 3 votes
I have started on the dataset
https://github.com/cmgchess/Titled-Tuesday-Data

With the help of Wayback Machine, I managed to access the tournaments up until March 1, 2016. Beyond that, I have no clue how to find.

Would appreciate if someone can help with the older events as well.

**UPDATE**
I completed the dataset starting from the first TT in 2014 upto now, and it gets updated every Wednesday
https://github.com/cmgchess/Titled-Tuesday-Data

Apart from that there is a pgn compilation as well contributed by rastallian
https://github.com/rastallian/chesscom-pgn-archive
and
https://chessnerd.net/chesscom-titled-tuesday-compilation/

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Tags: history, tournament, online-chess, database, chess.com
---


# Question
Title: (black) why the pawn H6 is not good move in this position?
(My turn\[black\])

I want to attack the g5 knight, so I up the pawn at H6, but the chess engine evaluate 3.4 to 1.3 my winning points. Instead engine recommended pawn D6, pawn D5, king H8 is better move. why the pawn H6 is not good move, but above moves are better?

# Answer
> 1 votes
**To avoid a weak square on d5.**

Black has a winning position with an healthy extra central pawn.

However, after 1...h6? 2.Ne4 the only defender of d5, the Nf6, gets exchanged. It means that White can get control of d5 for quite a long time (eventually Black will probably snap it back, but it will take a long fight), e.g. 2...Nxe4 3.Qxe4 d6 4.Bc4. Black is still much better, but with the backward Pd6 they have a complicated technical task ahead of them.

On the other hand, after 1...d5! the central pawn pair is immediately set in motion and dominates White pieces. Without access to e4,d4,c4,d5,e5,f4, White won't be able to mount any real counterplay, so Black can confidently continue with ...h6 (no Ne4 now) ...Be6, ...Qc7 or ...Qd7, ...Rad8, and force White to always be careful of pawn forks.

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Tags: sicilian-defense, pawns, knights, smith-morra-gambit
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# Question
Title: Mate Solving or problem solving software
I have some positions in my games which engine analysis indicates that some lines (not the ones I played) lead to a checkmate in 6 or 7 or 10 moves. But normal engines are not reliable here so I use ChestUCI as a proofing tool with some success till now.

Is there anything better and faster than ChestUCI that is also free? For those who don't doubt stock fish Please check Here https://talkchess.com/forum3/viewtopic.php?f=2&t=36714&start=10 and Here https://github.com/vondele/matetrack

# Answer
> 1 votes
So, it looks like you are searching for an engine that supports Mate Search. In regards to the UCI protocol, you would want an engine that supports the `go mate <x>` command. Stockfish does implement this command, so you should be able to use it to search for mate if a mate exists. I believe that some chess GUIs allow you to run a mate search, which should run this command.

However, Stockfish is a full-fledged chess engine, and it is built to find the best move in the position, not necessarily a forced checkmate. The way that it does this is by aggressively pruning the search tree so that it can focus the search on moves that are likely to be the best. A quick peek at the source code appears to show that the `go mate <x>` command is used to cut the search off only when a mate is found within x moves. I don't see anything that changes much in the way that the search operates based on this parameter.

Tools for finding checkmate, such as Chest UCI or the Fritz Mate engine, work differently. They will typically not prune any part of the search tree, and they do not include any sort of static evaluation. They merely search every possible move until it finds a sequence of moves ending in checkmate. This means that it will inevitably be slower than a standard engine.

Here's a snippet from an article that Fritz published in 2004.

> This brings us to why the Mate engine is so different from other chess engines: it has no "pruning" function. Mate will always evaluate every position it comes across in its search, ignoring nothing. And that's precisely why the engine appears to be so slow. It's not actually any "slower" than a regular chess engine (it's still evaluating approximately the same number of positions per second as a normal chess engine) -- it just looks slower because it's not cutting out any candidate moves, so it takes much longer for Mate to reach a particular search depth.

This TalkChess.com post from 2012 discusses a desire for a successor to Chest for finding checkmates, but it doesn't appear to have gone too far other than to conclude that chess engine developers are interested in building strong chess playing applications, so standard engines are probably not going to support this functionality. Somebody in the post mentioned that Critter is good at these endgame puzzles, but it doesn't look like its been worked on since 2012, and it is still an engine first and foremost. However, it wouldn't hurt to give it a try and see if it works well for any of the positions that you find to be problematic.

This more recent post for a couple months ago is asking for a similar application. They mention both Matefish and Huntsman in this thread as Stockfish forks which are meant for searching for mate, but also state that they are slower than ChestUCI or Gustav (which appears to be proprietary, German-language, and hard to acquire).

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Tags: analysis, software, checkmate
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# Question
Title: Why is Bd3 better than any other moves involving activating the bishop in this position?
The line is the following (Danish Gambit declined):

1. e4 e5 2. d4 exd4 3. c3 Nc6 4. cxd4 Bb4+ 5. Nc3 d6 6. d5 Bxc3+ 7. bxc3 Nce7

My question is why is Bd3 better than Bc4 or Be2 for instance? (None of them appear in the top 5 of Stockfish 14+NNUE at depth 30)

# Answer
> 5 votes
To answer your question “Why is Bd3 better than Be2 or Bc4?” with words rather than computer evaluations might be a more effective mode of conveying the ideas behind this.

Bd3 defends the e4 pawn, (Nf6 -attacking e4- is a likely move from black at some point, especially as black can castle once this happens), it develops a bishop and by vacating the f1 square and so prepares white for a future K- side castle. The white B on the b1 -h7 diagonal is a good placement for future threats against a castled black king.

Be2 leaves e4 undefended and as pointed out in the comments (Ian Bush) removes a square from whites f knight future development . Moving the B to c4 defends the already defended pawn leaving e pawn undefended.

Bb5+ ( to address one of the comments -David ) serves to loose a tempo or alternatively whites B in a phase of the game when piece develoopment should be the priority.

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Tags: opening
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