# Question
Title: Is the Caro-Kann principled? Why is there no refutation?
As a beginner, one quickly learns about chess principles, and in particular, opening principles.

The first openings most beginners learn are the Open Games. These were historically discovered first due to them being so logical and principled.

From the four objectively best replies to 1. e4, 1. ..e5 seems to be the most logical to me, closely followed by 1. ..c5.

..c6 theoretically and objectively speaking is on par with the aforementioned moves, but seems much less logical to me for the following (not exhaustive list of) reasons:

1. c6 takes less space in the center and allows White to grab the full center and a space advantage in the advance variation. In the classical mainline's pawn structure, Black doesn't even have a pawn in the center, with pawns on e6 and c6. Instead of preparing to put a pawn in the center with c6, Black could have placed a pawn in the center immediately with e5.
2. to activate the bishop before closing the pawn chain, it needs to be moved several times, and then it is simply traded off by White.
3. 1. ..c6 does not do anything for development. Not only doesn't it open lines for the bishops, it even blocks the natural development square of the knight. c5 seems much more natural for unbalancing the pawn structure, because we achieve c5 in one move, control part of the center from the side, and do not block c6 for the knight.

So what is the reason for it being such a good opening, despite the violation of some fundamental opening principles?

If one assumes that the principles are valid (i.e. breaking them will result in some disadvantage) and that there were no good reasons c6 allows Black to get other advantages in return to compensate the disadvantage(s) resulting from the violation of principles, then there must be a refutation (i.e. White should be able to prove a sizeable advantage).

# Answer
> 15 votes
An opening move (really any move) can be good for one of two basic reasons.

A. It accomplishes something you want to do.

B. It prevents the opponent doing something they want to do.

Because White starts, they can to some extent do what they want, and classically this means putting Pawns in the center on e4 and d4. Black must accept that this can happen, and after 1.e4 has four different policies to counter it.

1. Try to do the same with ..e5. (strategy A)
2. Challenge Whites center with ..d5 (strategy B)
3. Weaken the d4 followup with ..c5 (strategy C)
4. Allow the center with moves like ..d6, ..g6, ..b6 and snipe at it later (wait and see)

All four policies have proved to be viable. Assume that we have picked no. 2. Playing 1 ..d5 immediately is possible, but not everyone is happy with the loss of time involved in recovering the Pawn after 2.exd5, so more commonly the move is prepared with either ..e6 or ..c6. As you say, these moves delay development (especially ..c6), and do not directly occupy the center. What they do accomplish, as pointed out by Jonathan Rowson, is make White declare their intentions. When ..d5 comes, will White a. push, b. exchange or c. keep the tension? Black can base their future play on the choice made.

I do not think there is any strong a priori idea why this is a good idea, but it has turned out to work. The miracle of chess is that what seems to be a set of arbitrary rules just turns out to have philosophical implications.

# Answer
> 6 votes
Some things I want to add to what has already been said:

You don't control the center just by *placing* pawns there, but by *controlling center squares*. The move 1...c6 does directly fight for the center: it controls d5. When black puts a pawn there next, it will be protected by another pawn.

Yes, in the typical pawn structure, black has pawns on c6 and e6. But that implies a lot of control over the central square d5, especially since white's e4 pawn doesn't control it anymore. That makes it a very solid structure, there are no real weaknesses.

Black can develop quite freely, and will aim for the pawn break ...c5 later. White's e4 pawn was already exchanged, and if his d4 pawn can be exchanged as well, what's left of that great central control by white?

It's true that 1...c6 doesn't immediately help with development. The c-pawn will have to move again, or the knight has to go to d7. But all black replies to 1.e4 have *some* downside, chess would be very boring if there was an opening move with only pros and no cons. That black's position is very solid will help with achieving full development, a bit later.

# Answer
> 3 votes
1. c6 is quite good for fighting for the center: black essentially premoves d5 to challenge White's pawns. If you trade, the c-pawn becomes central. If White plays e5, the game becomes closed and all the "chess principles" give way to a completely different kind of play. (Or Black can even go for the second-main 3... c5 claiming that White's pawns are rather weak than intimidating and White himself has not done much with constant pawn moves.) Otherwise, e4 is hanging.
2. The bishop is moved one time: Bf5 or Bg4. If White attacks the bishop and it moves away, it's not a wasted tempo. Compare to French or Queen's gambit where the bishop is at best stupid and at worst just plain dead. Black would be happy to get rid of it at the cost of 2-3 moves.
3. It prepares other moves that are essential for development. If you play d5 immediately, you lose tempos after e:d5. If you play e5, White immediately gets the initiative attacking the pawn. e6, d6 block the bishops. Moreover, due to the relatively close nature of the positions arising, Black does not have to rush to develop pieces as fast as possible.

Generally, chess is a concrete game whose principles can't be reduced to a short list of rules. Still, general principles is not something Caro-Cann approach goes against, I believe: one just has to look deeper (point 3 here being an illustration).

# Answer
> 2 votes
The Caro-Kann and for that matter the French Defense are improvements on the Scandinavian Defense. They prepare 2...d5. By preparing 2...d5 with c6 or e6, White no longer prefers to respond immediately with exd5 because now black can promote the defensive c6 or e6 pawn to d5 and Black no longer loses a tempo from 2...Qxd5.

If White plays 3.exd5 then all of the disadvantages mentioned for c6 will be removed when Black responds with cxd5. Hence, this is not White's best response.

In the main line, 1.e4 c6 2.d4 d5 3.Nc3 the center is blocked and black is fighting for control of the center. It's not clear still how White can take advantage of Black's weaknesses in this closed center. It should be noted that Fischer's main weaknesses in the opening were against the Caro-Kann and French Defenses. Fischer was a classical styled player but could never find a way to satisfactorily show how to take advantage of the weakness of either of these defenses.

# Answer
> 1 votes
As a decent club player for fun only, I dislike facing c6 because for non-advanced book players, it often means my opponent is going to have a lot of canned responses to exploit any slight errors I make. As to your comments about taking over the center, as you move from beginner level -- if you prefer principles over book memorization as I do, I'd suggest focusing on relative strength of knights vs bishops -- lot of good books on that which made me much stronger. Combine that with learning to avoid holes in your pawn structure as pawns can advance but never back up, and the two edged sword of pawn moves will become more fascinating. I recommend Pandolfini - traps and zaps to help learn patterns, his endgame and mid-game tactics were good reads as well. While never venturing higher than expert myself, I built a chess engine who evaluated positions based on Pandolfini's techniques as much as I could and it plays at the master level and higher for blitz -- even if I turned off it's opening book. Most clubs -- inperson, or online have some classes where they will go through advanced positions and games -- even if you're like me and not planning on memorizing all the openings, these are usually rewarding. Happy hunting!

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


# Question
Title: Is chess a good game for recovering addicts?
In this interview to FIDE Master and psychologist Maria Rodrigo the interviewer asked her about chess and addictions:

> XL. There are those who are not able to prioritize and get hooked.
>
> M.R. Yes, because the dopamine rush during a game can be brutal. And that is something you have to learn to control. If you don't, you start a game, and then another, and another… And there is no one to stop. You lose hours of sleep… The problem of addiction is more typical in men than in women. Men are more hooked on video games and women on social networks.

I am a recovering addict. I passed through this clinic in Barcelona to recover from my addiction to alcohol and cannabis. They had a group where they used chess as therapy, so as a lover of the game I said to myself that chess couldn't be harmful for my therapy. But they banned me from chess, arguing I played obsessively. They said I could play once my two years treatment is finished. It was true that I played lots of online blitz, but I felt disgusted: why was I banned when they used chess as therapy for others?

Nowadays, I am in the ninth month of recovery. I left the clinic and I went to a psychologist. I don't play online blitz, but I play correspondence and I joined my club to play standard over the board games. My psychologist approve it but he is not specialist in addictions. At the clinic they wouldn't approve I am playing before two years of recovery.

I can read articles like this one on Chessbase where it is said they started a cognitive training through chess at a therapeutic community "recovering the cognitive functions (attention, memory, etc.) deteriorated by drug use, with the help of chess". But maybe this is focused on teaching how to play chess to people that didn't play lots of online chess while consuming drugs. And dopamine plays a role in addictions. At the clinic they said we were addicts to dopamine highs, so reading FIDE Master Rodrigo I would say it could still be harmful to my therapy and bring me closer to a relapse.

It is clear chess is good to treat other mental diseases like schizophrenia, and it looks good to teach recovering addicts how to play chess to recover the cognitive functions damaged by drug abuse (according to Chessbase article and my clinic), but is chess good for a recovering addict that played chess before his treatment started? Can it bring the patient closer to a relapse in drug use?

# Answer
Addiction is a complicated and multi-faceted issue, and although dopamine plays a role it's far from the only important factor to consider; this also depends on which type of addiction we're dealing with.

If we're talking about some sort of substance abuse (say, smoking, alcohol, hard drugs, etc.) then it's very common that a person becomes addicted to a substance that artificially affects the chemical balance in the brain/body. In this kind of scenario it is very hard to see how chess can make the original addiction worse, as any dopamine rush derived from chess is not caused by taking a substance to artificially affect the biochemistry of the brain. When considering how chess could have a positive effect on addiction in this regard it mostly comes down to it being a potentially effective form of distraction; one major problem with addiction is that a person can easily become a bit obsessed with whatever they're addicted to (especially when bored!), and in this case chess can serve as a good distraction making it easier to break the addiction/toxic habit.

Although chess can work as a therapy form for addiction it's not guaranteed to work. But it's a rather non-invasive kind of intervention in general, which is why I suspect you've seen it being used. Generally speaking, therapists tend to try the least invasive forms of therapy first and only go for more invasive methods if the addiction proves too strong (a common theme in, say, heroin addiction, where addicts often recieve "replacement drugs" so that they can weane themselves off of the heavier stuff).

So far I've only brought up substance abuse, but there are other forms of addiction that are worth addressing as well. Broadly speaking, practically anything can become an addiction, including chess itself. In this case, chess therapy would most likely not be a great idea, and I suspect if one has a problem with, for instance, online gambling, online blitz/bullet could prove to become a problem as well. In this case it's worth noting, however, that online blitz/bullet is not as financially draining as online gambling, although it can still have massive negative effects on the one suffering from the addiction. In essence, if your addiction is a form of "thrill chasing", then chess could end up being another addiction on the same theme if you're not careful.

At the end of the day, I'd say that chess as a therapy form depends on the addiction in question. So when you consider chess as a form of treatment for your addiction you must first have a clear idea of how your addiction works. What kind of addiction, what kind of triggers, how severe is it, etc.?

Whatever you take from this answer, I hope that your recovery process keeps on being successful. The answer I've given here is a rather non-specific one, and whether chess is the right thing for you is a question that only you can answer in the end.
> 18 votes

# Answer
Stack Exchange has a site dedicated to medical sciences.

If you open that, you'll immediately see that on the right column there's a disclaimer that you won't find on any other Stack Exchange site. It's a bit long, so let me cut the most important parts:

> **Stack Exchange Inc., and its sites including Medical Sciences Stack Exchange, is not a medical practice or healthcare provider and does not provide medical advice.**
>
> \[...\]
>
> Consult your own doctor for medical advice.
>
> \[...\]
>
> **Medical Sciences Stack Exchange is for information exchange only, and is not a substitute for medical advice, individualized diagnosis or treatment by a healthcare provider.**

This obviously covers the legal aspect, but it's more than that. Even if there were no lawyers and lawsuits in this world, that disclaimer would still have value. Because, well, it's true. In general you cannot trust users on any of these sites to really know what they are saying. Your health is too important to blindly trust some random stranger on the web, no matter how high their reputation is or how sincerely they are trying to help.

Besides, it seems to me that you've already got the answer from your clinic:

> But they banned me from chess, arguing I played obsessively.

I'm sorry, but I'm afraid you'll have to accept it. I hope I won't sound judgmental if I tell you that what you are really doing here is not looking for an answer (you've already got one; only, it's one you don't like), but rather for an excuse that will let you keep playing and ease your conscience.
Imagine someone posted an answer along the lines of

> Don't worry, those doctors don't understand anything! Playing chess can't be a problem, just go ahead and play as much as you want!

I suppose you'd be very happy to read it. And yet, who would you rather trust: the doctors that visited you and know your case specifically, or someone who probably has no idea what they are talking about, and who certainly doesn't know you, your clinical history, anything about you at all?

**So do the right thing, and do what your doctors say. Or in any case discuss *with them* what you should do.**

My best wishes for your full recovery!
> 53 votes

# Answer
First, others have indicated this, but Stack Exchange really isn't a substitute for competent medical advice from someone who knows all of the details of your specific case.

One general comment I will make, though: there is no "one-size-fits-all" in recovery from addictions, or even to your own recovery. That being said, the answer to your question is "some people will benefit and some people won't." You may find that things will even affect you differently in different phases of your recovery - something that helped you may stop working, and something that previously didn't help you could start helping you.

A direct implication of this, of course, is that the mere fact that it's therapeutic for some other people doesn't necessarily mean that it's therapeutic for you; it can be helpful for some people and useless, or even counterproductive, for other people. This is where you really need to consider the specifics of your case.

Also, let me pose the question in a different way: does the way you play chess cause you problems? Do you play it in a way that most people would consider excessive or unreasonable? Does it cause you problems in other areas of your life, such as work or personal relationships? If you answer "yes" to either of these, you should discuss with your psychologist whether you're playing in a way that's compulsive; otherwise, if you've discussed it with your psychologist and neither of those hold, I wouldn't worry too much about it - just make sure that you're being honest with your psychologist about whether or not those are the case.

Also, dopamine plays a role in *any* pleasurable activity, so personally I find the "dopamine argument" overly simplistic. Dopamine is involved in drug use because, at risk of oversimplifying things myself, addicts like taking drugs and alcohol. If there was no sense in which taking these substances was either positively or negatively reinforcing, no one would take them. (See, for comparison, the original brain simulation reward research, which helped to establish the biological mechanisms for addiction).

One more aspect of this that I would like to point out: besides the cognitive aspects of this, if you enjoy chess, it provides you with something to do other than drugs and alcohol, and a chess club can provide a social outlet that's a more positive influence in your life than spending time with people that are actively drinking or using.
> 5 votes

# Answer
Congratulations on your 9 months of recovery, @Universal\_learner! I'm grateful for over 30 years of recovery, primarily from cannabis but alcohol as well. The years have flown by faster than I could have imagined.

One thing that I've learned is that recovery from addiction is not just a matter of abstaining from unhealthy habits. It's also a matter of replacing the unhealthy habits with healthy ones. My experience is supported by neuroscience and the concept of neural pathways.

Your explicit questions are understandably generalized, but I believe how it affects you personally is what's truly important here. The answers to your questions aren't black and white. Treatment centers have to set rules in order for them to function successfully. Ultimately the decision is between you and your higher power. (For those unfamiliar with the 12-step concept of a higher power, I believe it's widely misunderstood. It can also be explained from a neurobiological perspective.)

Clearly you've made a distinction in separating what you believe to be unhealthy addictive chess versus chess that enables you to engage socially without drugs and alcohol. It sounds like you're sincerely trying to check and make sure you're being honest with yourself. IMHO, just keep doing that, with the support of your therapist and higher power.

In early recovery, I would make difficult decisions by asking my higher power and myself which decision felt like it was most supportive of my sobriety versus leading to relapse. Over the years that question has evolved into seeking spiritual guidance to do the next right thing. That guidance this evening was to answer your question, and that answer was different than I expected!

Best wishes to you on your journey, @Universal\_learner! May you answer a question like this 30 years from now, one day at a time!
> 3 votes

# Answer
Anything you can find that keeps you sober is a great activity and since the relapse rate is so high ignore anybody who thinks they got sobriety figured out if they did they would be an instant celebrity and could name their price on consultation. If you find that playing keeps you from obsessing on your former life then dive on in. The first year is probably the hardest so I would keep a journal and document your journey. When you are successful perhaps even publish your recipe so others may follow.
> 3 votes

# Answer
Yes, of course.

Any game - any activity - that depends on continued application of the powers of the mind should help recovering addicts.

Unless no games are good, how could chess not be?
> -2 votes

---
Tags: psychology
---


title: Danish Gambit normal variation

text:
# Question
Title: Danish Gambit normal variation
I'm studying the Danish gambit lines and trying to understand a particular move:  The engine (depth 30 Stockfish 14.1), and theory (by that I mean GrandMasters talking about it) suggest Nc3 without giving much explanation. I feel like it's sort of blocking our own bishop and prefer Nd2 (which has the benefit to protect both bishop on c4 and e pawn). However, the engine says -1.31 for this and -0.50 for Nc3. Are there any rational explanations as to why this is not better?

# Answer
The most obvious point of placing the knight on c3 instead of d2 is that it helps white maintain better control over the center of the board, although there is a more subtle (and important!) point to it. Consider what happens in the following variation, which is the computer's top line: 6.Nc3 Nf6 7.Qb3! (a double threat, as both the bishop on b4 and the pawn on f7 is hanging) 7...Bxc3+ (practically forced) 8.Qxc3. White will castle queenside later to make it easier to attack black's kingside.

So, by placing the knight on c3, white manages to setup a menacing (Queen+Bishop) battery along the a1-h8 diagonal a few moves down the line. This gives white some initiative, which compensates for the material disadvantage.

If we instead go for 6.Nd2, it is not possible to play Qb3 and set up this battery since black will then just capture on d2 with check, which would be an absolute disaster for white. Therefore, the computer's top line in this case becomes: 6.Nd2 Nf6 7.Ngf3 0-0 8.0-0, which is a lot less menacing for black to deal with. And since white is already two whole pawns down, this relatively meek setup just doesn't cut it.

The contrast in quality between these two seemingly "good" moves really highlights the validity of the basic opening principles. Although 6.Nd2 adheres to the principle of development, 6.Nc3 adheres both to the principle of development as well as the principle of central control. Therefore, a proponent of these principles (which I am, btw) would say that 6.Nc3 is the correct move in this case, even without the tactical justification behind it.
> 7 votes

---
Tags: opening, gambits
---


# Question
Title: Which legal position has the smallest number of moves in a "forced loop"?
Consider this (illegal) position.

```
[FEN "5n1k/3p1p1p/3PpPpP/4P1P1/1p1p4/pPpPp3/P1P1P3/K1N5 w - - 0 1"]

```

If we do not consider the position's illegality, and the fact that it is clearly unwinnable by eiter player (and therefore an automatic draw even if either of the players resgined, ran out of time, etc), then this position has an interesting property. Regardless of what move every player does (which is obvious in this case, since there is always only one legal move), the position results in forced threefold repetition in 4 moves.

Now here arises a question, basically a problem creation: Which legal position has the least amount of moves to make threefold repetition, assuming no player wants to repeat the positions?

# Answer
This legal position should fit the bill for the least amount of units needed and the least amount of moves. There is one king, one bishop, and four pawns for each side - a total 12 pieces. The threefold repetition is forced no matter what moves the players make since they only have one legal move each time. It's basically your idea in a legal and lighter setting.

```
[FEN "5b1k/4p1p1/4P1P1/8/8/1p1p4/1P1P4/K1B5 w - - 0 1"]

```
> 4 votes

# Answer
The questioner invited us to ignore illegality or dead position rule.

> Title: question: which legal position has the smallest number of moves in a "forced loop"?

Forced draw by repetition in the shortest number of moves. Well that's 4 single moves = 2.0 double moves. Same number of units as Rewan Demontay, but slightly lighter position:

```
[FEN "5b1k/4p1p1/4P1P1/5pP1/5PpK/6P1/8/8 w - - 0 1"]

```

Eventual draw by repetition, also ignoring 50/75 move rules Well just two kings on the board is enough. There are 3,612 (= 36*55 + 24*58 + 4\*60) arrangements of the two kings. Each might be achieved with either white or black to play, and appear twice. So after at most 14,448 single moves (=7,224.0 double moves) a position will occur for the third time. Does the connectedness of the position graph allow this value to be achieved "in practice"? Can the draw be postponed this long? I don't know, but I guess yes.
> 2 votes

# Answer
This is an even lighter position that's sure to *eventually* produce a triple repetition if the 50- or 75-move rule doesn't end the game sooner:

```
[FEN "4k3/8/8/1p2p2p/1P2P2P/8/8/4K3 w - - 0 1"]

```

one can also mix and match:

```
[FEN "5bk1/1p2p1p1/1P2P1P1/8/8/8/8/4K3 w - - 0 1"]

```

(Without the b-pawns it's still a dead draw but the game might end by stalemate instead of repetition.)
> 1 votes

---
Tags: problems, threefold-repetition, forced-move
---


title: What is this opening called?

text:
# Question
Title: What is this opening called?
I would like to know what this opening is called, if someone has made a bad move, and who stands better.

Finally if this opening is played by grandmasters here.

# Answer
> 4 votes
According to Wikipedia, it is the Marshall defense, played by Frank Marshall in the 1920s, until he gave it up after losing to Alekhine in 1925 at Baden Baden.

# Answer
> 3 votes
1. d4 d5 2. c4 form the start of the Queen's Gambit family of openings. Black's reply ...Nf6 is weak enough to possibly not deserve a name (at least none comes to mind at the moment). Black's typical reply is either ...e6, heading towards the Orthodox Queen's Gambit Declined family tree, ...c6 leading to the Slav tree, or ... dxc4 and the Queen's Gambit Accepted. There are also other lines of varying degrees of respectability, but these are the main ones.

The text move (...Nf6) just begs white to take the d-pawn, and whether black recaptures with the knight and gets chased by e4 or recaptures with the queen and gets chased by Nc3, White gains a significant advantage. In the Chessbase Online DB, white scores around 80% in either line, which seems to me a good reason to stop thinking about Nf6 and try something sounder.

# Answer
> 2 votes
You can click on the 'book' to view the opening , and can also select whether to check for this position in grandmaster games or in standard lichess games , and the moves usually next played.

If you click on the 'microscope' , you can access the computer analysis by scrolling down and clicking on 'request computer analysis' - which tells you about the blunders and best moves etc.

You can also start lichess server analysis for the moves by toggling the switch beside 'Stockfish 14+ NNUE' , which tells you the engine recommended moves at each point for each side .

---
Tags: opening, opening-traps
---


# Question
Title: Is there a variant in which any piece can be taken 'en passant'?
The en passant rule for pawns can be thought of as an 'attack of opportunity', such as in D&D - the attacking pawn would have been able to take the moving pawn as it passed through the first space.

When thought of this way, an obvious idea for a variant would be to generalise this by allowing the same behaviour in all cases, i.e. if during their journey a piece passes next to another piece that could have taken it, the next player has the option to invoke 'en passant' and take the piece where it would have been. Knights would be immune, as they 'jump' and thus do not pass through intermediate squares.

My question is, does this variant already exist, and/or is there a reason why it wouldn't work?

# Answer
There is a variant called en passant chess.

Description from the source.

#### En Passant Chess

In standard chess, a pawn moving more than one step (i.e. two steps) can be captured by another pawn en passant on the move immediately following the multistep move.

Let us extend this rule to all pieces:

* We use knightriders instead of knights. The king is a bit special (see below), and we use the other normal chess pieces.
* A piece making a multistep move can be captured by an opponent's piece on its way, as long as this capture is done on the move immediately following the multistep move.
* A piece making a multistep capture can be captured the same way. The piece it captured is not returned to the board (i.e. the capture is not undone).
* As a king only makes a multistep move in castling, and it is already illegal to move it through a checked square, it cannot be captured en passant. It may however capture another piece en passant.
* A king may make a knight (not knightrider) move, in addition to its normal king move, to capture another piece en passant. It may not use this move otherwise, e.g. to capture another piece directly.
* The knightrider only steps on the squares a knight-move away from one another. For example, a knightrider moving from g1 to d7 can only be captured at f3 and e5. We can say that the move unit of a knightrider is a knight move.
* All other pieces step on all squares between the starting and ending squares, so their move unit is a king move. Of course, the move unit of a rook is a wazir move, and that of a bishop is a ferz move only.
* The only multistep move a pawn may make is the two-steps initial move, but beware that in this game it can be captured en passant by any piece!
* Other rules are the same as in normal Chess.

*Written by Andy Kurnia. HTML conversion by David Howe.*
> 3 votes

# Answer
I don't think that there exists such a variant .

The reason it was added , was that if one side's pawn is on its 5th rank(other's 4th) , and on an adjacent file , the other side has a pawn on the 2nd file , and moves it in one move to the 4th rank , then had it been moved to the 3rd rank , it would have been possible to capture it.

For example : White has a pawn on f5 Black to move , plays e7-e5 White plays fxe6 en passant

This is because the 2-square pawn move was introduced later - had it not been , then black could only play e7-e6 , resulting in fxe6 .

This would not be possible with any piece.
> 0 votes

---
Tags: chess-variants, en-passant
---


title: Longest "death certificate"

text:
# Question
Title: Longest "death certificate"
Give a legal position which is "dead" but would take (assuming the §5.2.2 about dead positions wouldn't exist) maximally long to play out until an automatic draw by fivefold, 75 moves or statemate results.

```
[FEN "5b1k/4p1pB/4PbP1/8/8/8/8/7K w KQkq - 0 1"]

```

This is a non-example (in a help-game e7 can be taken eventually) so the obvious idea adding more bishops doesn't work!

# Answer
> 8 votes
Here is such a position.

```
[FEN "1k6/p1p1p1p1/P1P1P1P1/8/8/8/PKP1P1P1/8 b - - 0 1"]
[startlfipped ""]

```

With Black to move, no side can make any progress. White still has plenty of pawn moves to make to reset the 75 move counter. It's a legal position as well.

Interestingly, this is a position that humans understand better than engines! It's a draw, even if Stockfish insists it's +7.

**EDIT:**

As pointed out in the comments, adding 4 black pawns that White can take adds another 12 resets to the 50 (75 if unclaimed) move counter.

Also, a wBh7 that cannot escape and will eventually be taken would add yet one more reset but this is not possible since this bishop never could escape f1 to get there.

```
[FEN "kR6/p1p1p1p1/P1P1P1P1/p1p1p1p1/8/8/PKP1P1P1/8 b - - 0 1"]
[startlfipped ""]

```

---
Tags: records, dead-position
---


# Question
Title: Why is forking the king and rook a blunder in this Halloween Gambit line?
```
[FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR"]
[Title "Halloween Gambit Game"]
[StartPly "22"]

1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4 Nc6?! 6. d5 Ne5 7. f4 Ng6 8. e5 Ng8 9. d6 cxd6 10. exd6 Nf6?? 11. Nb5 Qb6 12. Nc7+??

```

On move 12, White plays **Nc7+**, forking the black king and rook. This move wins some material so I expect that it should be good for White. Also, I believe that this fork is one of the main ideas for White in the Halloween Gambit.

However, Stockfish labels it a blunder and the evaluation goes from around `+1.5` to `−1.5`. Why?

# Answer
> 5 votes
White only wins one point in material for this tactic but loses a load full in position. It is complicated and you must run through the line to see why it fails.

The game will continue like this:

```
[FEN ""]
[Title "Halloween Gambit Game"]
[StartPly "23"]

1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4 Nc6?! 6. d5 Ne5 7. f4 Ng6 8. e5 Ng8 9. d6 cxd6 10. exd6 Nf6?? 11. Nb5 Qb6 12. Nc7+?? Kd8 { Pretty much forced. This looks weak but actually it will become evident that Kd8 will allow the rook to develop, whereas White is losing a tempo on a piece that will soon be lost. } 13. Nxa8 Qc5 { The queen must move and it is debatable which square is best but let’s examine Qc5. }

```

White cannot save the knight with **14. Nc7**, because after **14… Bxd6** the knight has nowhere to go except back to a8 where it is effectively out of the game. **15. Nb5** doesn’t work because of **Re8+**, and whichever piece White uses to block the check becomes pinned and the knight is left hanging.

So White should not even consider trying to save the knight and focus on defense. Because, irrelevant of what White now does, the Black attack is coming. Black will soon play **Bxd6**, **Re8** and Black is attacking the king in the middle of the board with queen, rook, bishop and two knights. White’s pieces are all poorly positioned to defend.

However, if White avoids **12.Nc7+**, the d6 pawn is actually far more powerful as it prevents Black from developing the bishop and rook into the attack. Hence, black does not have the same powerful attack and **Nc7** remains on the cards as a threat for later.

**Conclusion:** This is a lesson in permanent weaknesses and strengths. The d6 pawn is worth more than a pawn because it is preventing the development of black pieces. Capturing the a8 rook not only loses a tempo but also loses a permanent positional strength.

---

Consider the following alternate line suggested by Stockfish:

```
[FEN ""]
[Title "Halloween Gambit Game"]
[StartPly "22"]

1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Nxe5 Nxe5 5. d4 Nc6?! 6. d5 Ne5 7. f4 Ng6 8. e5 Ng8 9. d6 cxd6 10. exd6 Nf6?? 11. Nb5 Qb6 12. f5 Ne5 13. Bf4 Qc5

```

Now it is evident that White will be able to complete development while Black will struggle to develop the rest of its pieces. Black never has time to play **Kd8** or **Rb8**, so the fork always remains a tactic in play.

---
Tags: opening, analysis, beginner, gambits, fork
---


# Question
Title: Players who are consistently rated over 2500 but are not GM
How many players are consistently rated over 2500 but are not grand masters?

(I am interested in players who have been over 2500 for a few years while actively playing chess.)

—----

See also Why wasn’t Rashid Nezhmetdinov a grandmaster?

# Answer
Here is a list of the 50 currently active players rated over 2500 in the January 2022 list with no GM title sorted by current standard rating in descending order:

| # | Full Name (Last, First) | FIDE ID | Rating | Born |
| --- | --- | --- | --- | --- |
| 1. | Sviridov, Valery | 4120680 | 2562 | 1991 |
| 2. | Livaic, Leon | 14531534 | 2559 | 2000 |
| 3. | Petrov, Martin | 2911086 | 2547 | 2000 |
| 4. | Sosa, Tomas | 121576 | 2546 | 1998 |
| 5. | Obolenskikh, Dmitry | 4156013 | 2543 | 1985 |
| 6. | Teclaf, Pawel | 1185934 | 2542 | 2003 |
| 7. | Vazquez, Guillermo | 3702308 | 2536 | 1997 |
| 8. | Kourkoulos-Arditis, Stamatis | 4221990 | 2532 | 1998 |
| 9. | Noe, Christopher | 24692018 | 2530 | 1996 |
| 10. | Gazik, Viktor | 14928752 | 2530 | 2001 |
| 11. | Kriebel, Tadeas | 330027 | 2526 | 1995 |
| 12. | Iermito, Sebastian | 114286 | 2525 | 1993 |
| 13. | Nenezic, Marko | 912123 | 2525 | 1995 |
| 14. | Janik, Igor | 1159259 | 2525 | 2000 |
| 15. | Trushnikov, Sergey | 34299360 | 2525 | 1975 |
| 16. | Mousavi, Seyed Khalil | 12511099 | 2524 | 1998 |
| 17. | Muradli, Mahammad | 13409301 | 2523 | 2003 |
| 18. | Vernay, Clovis | 633046 | 2523 | 1989 |
| 19. | Sankalp, Gupta | 5097010 | 2522 | 2003 |
| 20. | Galperin, Platon | 14165414 | 2522 | 2003 |
| 21. | Lamard, Guillaume | 600261 | 2520 | 1997 |
| 22. | Kazakouski, Valeriy | 13507443 | 2520 | 2000 |
| 23. | Murzin, Volodar | 44155573 | 2519 | 2006 |
| 24. | Makarian, Rudik | 44105681 | 2517 | 2004 |
| 25. | Drygalov, Sergey | 24171743 | 2517 | 1999 |
| 26. | Shuvalova, Polina | 24171760 | 2516 | 2001 |
| 27. | Lobanov, Sergei | 24183750 | 2516 | 2001 |
| 28. | Dai, Changren | 8608156 | 2515 | 1999 |
| 29. | Le, Tuan Minh | 12401153 | 2514 | 1996 |
| 30. | Hauge, Lars Oskar | 1509276 | 2513 | 1998 |
| 31. | Ponizil, Cyril | 322202 | 2513 | 1991 |
| 32. | Noritsyn, Nikolay | 2604922 | 2512 | 1991 |
| 33. | Gavrilescu, David | 1227190 | 2512 | 2003 |
| 34. | Erenberg, Ariel | 2811634 | 2512 | 2001 |
| 35. | Mitrabha, Guha | 5057000 | 2510 | 2001 |
| 36. | Khanin, Semen | 4111990 | 2509 | 1999 |
| 37. | Neugebauer, Martin | 14923432 | 2509 | 1999 |
| 38. | Druska, Juraj | 14915650 | 2509 | 1994 |
| 39. | Beerdsen, Thomas | 1030108 | 2508 | 1998 |
| 40. | Wynn, Zaw Htun | 13002783 | 2508 | 1982 |
| 41. | Paehtz, Elisabeth | 4641833 | 2507 | 1985 |
| 42. | Matviishen, Viktor | 14129850 | 2507 | 2002 |
| 43. | Triapishko, Alexandr | 14122286 | 2506 | 2000 |
| 44. | Berchtenbreiter, Maximilian | 24641120 | 2506 | 1994 |
| 45. | Nikitenko, Mihail | 13506862 | 2506 | 2000 |
| 46. | Neef, Maximilian | 24692085 | 2504 | 1996 |
| 47. | Brenninkmeijer, Joris | 1000047 | 2503 | 1969 |
| 48. | Annaberdiev, Meilis | 14000563 | 2503 | 1985 |
| 49. | Blohberger, Felix | 1632051 | 2503 | 2002 |
| 50. | Salemgareev, Tagir | 24199052 | 2503 | 2002 |
> 9 votes

# Answer
* Download 2022-02 FIDE standard xml rating file.
* Get players who are not GM or WGM with rating above 2500 and not inactive based from the xml file `flag` tag.
* Scrape certain FIDE page based from fideid to get player rating history.
* Select player with rating info from year 2018 to present having an average rating of above 2500 for that period.

#### Result

The m\_rating is the mean rating from 2018-01 to 2022-02, rating is the current rating as of 2022-02. Table is sorted by m\_rating followed by rating.

```
      fideid                   name country sex title  rating   age  m_rating
0    4120680       Sviridov, Valery     RUS   M   NaN    2561  30.0      2550
1    4156013    Obolenskikh, Dmitry     RUS   M    IM    2547  36.0      2540
2     114286     Iermito, Sebastian     ARG   M    IM    2525  28.0      2524
3   24692018       Noe, Christopher     GER   M    IM    2515  25.0      2523
4     912123         Nenezic, Marko     SRB   M    IM    2525  26.0      2521
5   14000563    Annaberdiev, Meilis     TKM   M    IM    2503  36.0      2520
6   14928752          Gazik, Viktor     SVK   M    IM    2543  20.0      2518
7     330027        Kriebel, Tadeas     CZE   M    IM    2519  26.0      2517
8   24183750        Lobanov, Sergei     RUS   M    IM    2534  20.0      2513
9     633046         Vernay, Clovis     FRA   M    IM    2523  32.0      2513
10    121576            Sosa, Tomas     ARG   M    IM    2547  23.0      2512
11  12401153          Le, Tuan Minh     VIE   M    IM    2514  25.0      2510
12  14122286   Triapishko, Alexandr     RUS   M    IM    2506  21.0      2509
13   2604922      Noritsyn, Nikolay     CAN   M    IM    2512  30.0      2502
14   4111990          Khanin, Semen     RUS   M    IM    2509  22.0      2502
15  12511099  Mousavi, Seyed Khalil     IRI   M    IM    2524  23.0      2501
16    655830         Bailet, Pierre     FRA   M    IM    2509  33.0      2501

```
> 5 votes

---
Tags: fide, rating, grandmaster
---


# Question
Title: An interesting question from a Leela vs Komodo blitz game
In a blitz game between Leela zero and Komodo, the following position came up.

```
[title "Leela Zero vs Komodo"]
[fen "8/8/2p3k1/4bpp1/2P3P1/4BK1P/5P2/8 w - - 0 1"]

```

With White to move. Or WHITE King on f3 Bishop on e3 pawns on c4 f2 g4 h3 BLACK King on g6 Bishop on e5 pawns on c6 f5 g5. WHITE to move.

The game ended with a draw, although at a certain point both engines gave quite a high evaluation score. We know Leela is notoriously weak in the endgame. Did Leela zero miss something? What happens with perfect play?

# Answer
Tried to run a match between stockfish 14.1 each at 2 threads with 6-men ending tablebase on TC 15m+5s.

#### Result

```
[Event "Engine match"]
[Site "?"]
[Date "2022.02.01"]
[Round "1"]
[White "Stockfish 14.1"]
[Black "Stockfish 14.1"]
[Result "1-0"]
[FEN "8/8/2p3k1/4bpp1/2P3P1/4BK1P/5P2/8 w - - 0 1"]
[SetUp "1"]
[TimeControl "900+5"]

1.Bb6 { [%emt 0:00:17] [%eval 308,60] } 1...Bd6 { [%emt 0:00:18] [%eval 341,72] } 2.Ke3 { [%emt 0:00:12] [%eval 312,51] } 2...Be5 { [%emt 0:00:09] [%eval 337,65] } 3.Bd8 { [%emt 0:00:23] [%eval 306,62] } 3...Bc3 { [%emt 0:00:12] [%eval 350,67] } 4.Bc7 { [%emt 0:00:09] [%eval 300,62] } 4...Kf6 { [%emt 0:00:11] [%eval 341,61] } 5.Kf3 { [%emt 0:00:22] [%eval 291,68] } 5...Bd4 { [%emt 0:00:16] [%eval 357,60] } 6.Kg3 { [%emt 0:00:11] [%eval 320,74] } 6...f4+ { [%emt 0:00:17] [%eval 371,61] } 7.Kf3 { [%emt 0:00:11] [%eval 548,65] } 7...Ke7 { [%emt 0:00:40] [%eval 555,65] } 8.h4 { [%emt 0:00:12] [%eval 548,54] } 8...Kd7 { [%emt 0:00:14] [%eval 555,53] } 9.Bb8 { [%emt 0:00:12] [%eval 551,54] } 9...Kc8 { [%emt 0:00:14] [%eval 559,56] } 10.hxg5 { [%emt 0:00:13] [%eval 850,49] } 10...Kxb8 { [%emt 0:00:50] [%eval 718,55] } 11.Kxf4 { [%emt 0:00:13] [%eval 914,44] } 11...Kc7 { [%emt 0:00:43] [%eval 865,47] } 12.Kf5 { [%emt 0:00:13] [%eval 957,42] } 12...Kd6 { [%emt 0:01:54] [%eval 1005,54] } 13.f4 { [%emt 0:00:15] [%eval 1047,39] } 13...Kc5 { [%emt 0:00:22] [%eval 1018,48] } 14.Ke6 { [%emt 0:00:14] [%eval 1284,44] } 14...Kxc4 { [%emt 0:00:29] [%eval 1538,43] } 15.f5 { [%emt 0:00:15] [%eval 1576,37] } 15...c5 { [%emt 0:00:53] [%eval 15257,36] } 16.g6 { [%emt 0:00:17] [%eval 15258,30] } 16...Kb4 { [%emt 0:00:19] [%eval 15260,38] } 17.f6 { [%emt 0:00:17] [%eval 15260,44] } 17...c4 { [%emt 0:00:11] [%eval 15261,40] } 18.g7 { [%emt 0:02:38] [%eval 32726,43] } 18...c3 { [%emt 0:00:12] [%eval 15262,44] } 19.g8=Q { [%emt 0:00:15] [%eval 32730,42] } 1-0

```
> 2 votes

# Answer
Again , in the following endgame Leelazero vs Dragon WHITE King on g1 Bishop on d3 Knight on e2 pawns on a3 b2 d4 e5 f2 h3 BLACK King on g8 Knights on a7 c6 pawns on a4 b6 d5 e6 f5 h7 BLACK to move the endgame appeared to be winning for White. Analysis 40 minutes on Stockfish 14 NNUE 4 thread , with a second iteration at a critical point. It is confirmed Leela zero is far from infallible in the endgame. In the game, it terminated with a draw.
> -2 votes

---
Tags: computer-chess
---


# Question
Title: Optimising Stockfish parameters when batch-analyzing with python-chess
I am running a python script that analyzes a large batch of PGN games (each of ~5,000 games) across and exports the games evaluations. It calls Stockfish 14 to analyze each game at depth 20. \**\[EDIT: I've since read that newer versions of Stockfish can actually take LONGER to reach the same depth as older versions, because they have a wider search and thus more nodes per second. So I am considering setting a position time limit rather than depth limit.\] \**I am using a virtual machine with 32 vCPUs and 64GB RAM but processing is slow (though `htop` claims it is using 99% of CPU%). I haven't modified any Stockfish settings since installing.

1. What parameters should I set to minimize the processing time?
2. How can I change these settings so that they will be recognized by the call from python-chess? The relevant lines of the python code are:

```
engine = chess.engine.SimpleEngine.popen_uci(stockfish)
engine_depth = 20
def evaluate_game(game, engine, limit=chess.engine.Limit(depth=engine_depth)):
   board = game.board()
   info = engine.analyse(board, limit=limit)

```

# Answer
> 2 votes
The link refers to stockfish 11 and you are now using stockfish 14, so that article is irrelevant.

1. To minimize processing time you can adjust the depth or movetime or both. The question is what analysis quality are you up to?
2. To control analysis time use the following example.

```
engine = chess.engine.SimpleEngine.popen_uci(stockfish)
movetimesec = 5
def evaluate_game(game, engine, limit=chess.engine.Limit(time=movetimesec)):
   board = game.board()
   info = engine.analyse(board, limit=limit)

```

To use both depth and time you can use the following.

```
engine = chess.engine.SimpleEngine.popen_uci(stockfish)
movetimesec = 5
depth = 20
def evaluate_game(game, engine, limit=chess.engine.Limit(time=movetimesec, depth=depth)):
   board = game.board()
   info = engine.analyse(board, limit=limit)

```

In this case, when the engine reaches depth 20 before the time limit of 5 sec, then the search is aborted. If analysis time of 5 sec is reached first before depth 20 then the search is also aborted.

In ending phase reaching depth 20 is very fast as there are less pieces to evaluate while in the opening phase reaching depth 20 could be a challenge and movetimesec of 5 might be consumed first, depends on your hardware. It is a matter of analysis quality you want and the total time to finish the analysis.

#### Measuring quality and analysis time

1. Analyze game1 (more games and get the average) with depth 20, remember the total time.
2. Analyze game1 (more games and get the average) at movetime of 5 sec, remember the total time.
3. Run an engine vs engine match, sf14\_depth20 vs sf14\_5sec.

step 1 and 2 compare the total analysis time while step 3 compares the analysis quality.

I guess sf14\_5sec will win over sf14\_depth20, but you have to test this on that hardware.

If sf14\_5sec will beat sf14\_depth20 in a match of 100 or so games and step 2 is lower than step 1 then sf14\_5sec would be a candidate for a good setting.

Now do some comparisons with `sf14_5sec vs sf14_5sec_depth20` and `sf14_depth20 vs sf14_5sec_depth20`. Keep a note on quality and total analysis time.

---
Tags: engines, analysis, stockfish, python
---


# Question
Title: Why doesn't Black develop the light-square bishop after 1. d4 d5 2. Nf3?
After 1. d4 d5 2. Nf3 Stockfish gives the best move as 2...e6, entering a QGD position.

Why does Black voluntarily block the LSB instead of develop it first with 2...Bf5?

# Answer
> 5 votes
First of all, don't attribute too much weight to engine evaluations that early in the game. Rather look at the established theory, and what you want to achieve.

For example, after 1. d4 d5 2. Nf3, I am far from convinced that 2. ...e6 is the best move. I am sure that the most common move is 2. ...Nf6, which keeps your options open. You could for example play the Slav defence (...c6 after White goes c4) and develop your light-squared bishop later. Also in many lines of the London System you can still develop that bishop before going ...e6.

That said, I have indeed played 2. ...Bf5 on a few occasions in serious tournament games. One line I dislike is 3. c4 e6 (c6 is a not so great Slav line) 4. Nc3 Nf6 (Nc6 is possible, but has its own issues) 5. cxd5 exd5 6. Qb3 Nc6 7. Bg5 and the double attack on d5 and b7 basically forces 7. ...Na5 8. Qa4+ c6 9. Bxf6 gxf6 which isn't horrible for Black, but probably slightly worse than what you can get by defending a standard QGD, especially with White committed to an early Nf3 which rules out some critical lines.

# Answer
> 7 votes
The absence of the bishop causes black problems. The weakening of b7 and the a4-e8 diagonal will often create more difficulties than the freedom of the bishop is worth.

---
Tags: opening, queens-gambit-declined
---


# Question
Title: Is there a site that pairs up wanna be coaches with students
People who either love teaching for free or that want to build some cliental who will give free lessons for a period of time or to practice there art of dispensing knowledge. Is there such a thing on the major sites that offer free chess or has anybody heard of talk of offering such a thing chess.com or lichess.com perhaps.

# Answer
> 4 votes
Lichess has a coaches page where titled players offer coaching in several languages.

Some of them offer discounts and a free first lesson.

---

If you are looking for something more casual, there are some chess Discord servers that might be of interest to you. Chess Academy has a channel called **#find-training-partners**, which is used by players who want to share knowledge and help each other. Another one is ChessDojo, which also has a **#find-training-partners** as well as a **#coaching-discussion** channel.

# Answer
> 1 votes
As you seem to have suspected, both lichess.org and chess.com have resources where students can find coaches:

Some other suggestions for finding a coach:

* A web search can also find coaches. The lichess and chess.com pages above are the only results I saw on the first results page which provide a list. The remaining results are web sites of coaches, which is itself a list you can look through.
* US Chess has a list of coaches who have gone through its certification program at: http://www.uschess.org/index.php/Scholastic-Misc/Certified-Chess-Coach-List.html
* Results will vary, but your local/regional/national organization may list coaches in your area.

Note I couldn't find a list for FIDE certified trainers, although they have a program for that. Perhaps someone with better search skills or more patience will have more luck.

At least some coaches will offer free lessons as a sample. Some may offer lessons or group classes on a "Pay what you can" basis. However, I do not know of a site which shows a list of people with such offers. Some of the coaches on the lichess and chess.com lists say they offer first lessons for free. If they don't say that, you can ask, but it will (probably) have to be on a coach-by-coach basis.

---
Tags: online-chess
---


# Question
Title: Does FIDE publish the results of all rated games?
It seems a lot more information could be gained by fully processing a game results database then just updating a number only while looking at the previous months results. For example is a person's rating a true reflection of a wide range of players or have they mostly played in a "closed" subset of player against other players which do the same?

# Answer
> 2 votes
Additional comment question:

> How do I find the results of all games that have been rated by FIDE?

FIDE publish lists of tournaments for each federation for both future tournaments that have been registered with FIDE and for past tournaments which have been played, reported to FIDE and rated. FIDE publish the data from the tournament report files here on an individual tournament basis.

That means the data is not made available to the public in an easily downloadable format. If you want the data you will have to screenscrape the thousands of web pages containing the data you want.

This also does not cover all tournaments that have ever been rated by FIDE, only those going back as far as 2001 and even then the old data recorded may only include player scores per tournament rather than individual results.

Let's look at an example to see how this works.

In December 2021 I was chief arbiter in an IM norm tournament about 15 miles from where I live. That was registered to be reported in the January 2022 list. To find that tournament go to the FIDE tournament list for England January 2022.

If you want to see other federations then at the top right hand side there is a drop down list which allows you to select other federations. At the bottom of the page there is another drop down list which allows you to select period going back as far as 2001.

Going back to the January 2022 England list you will see that all the tournaments have a blue icon on the left hand side. One of them, the IM tournament also has a brown icon. The blue icons are the tournament reports for the individual tournaments. These show the results of individual games in each round. You can see the results for the IM tournament here.

The brown icon is a pgn file link. Clicking on it allows you to either view individual games in FIDE's game viewer or download the whole file. The organiser is required to provide this file for all tournaments which have been registered for norms. Failure to do so would invalidate any norms won. Tournaments where norms are not available are not required to provide these files and so most don't.

# Answer
> 4 votes
> Does FIDE publish the results of all rated games?

No. FIDE only publish all the results of FIDE rated games. They do not publish results of games played in tournaments where the games are rated by the national federation but not FIDE.

For example in the UK, where there are actually 4 federations - England, Scotland, Ireland and Wales - most chess competitions are not FIDE rated but are rated by the national federations. The same is true in the US.

In some countries, Israel for example and some of the European mainland countries, most chess is FIDE rated but there are usually some competitions for which it makes no sense to FIDE rate. Examples would be those for very weak / immature players (i.e. young children) where rules like "2 illegal moves = lost game" make no sense and themed tournaments where article 2.3 of the FIDE Laws of Chess are not obeyed.

Although Chess960 *is* covered in the "Guidelines 2" section of the Laws those games are also not FIDE rated.

FIDE's main rating system also only includes over-the-board FIDE tournaments. It does publish online ratings separately but only for games on its own Online Arena platform.

---
Tags: fide, rating
---


# Question
Title: How do rating systems cope with clusters of players who nearly always only play people within their cluster?
Given the issues with rating people who mostly play within a cluster that contains few people who play outside the cluster, I was expecting rating systems to take more notice of results against another player who was well connected to many different clusters of players. Yet they seem not to. What am I missing in my understanding?

# Answer
Your understanding is correct, at least for the Elo system (and systems derived from it). These systems only make adjustments to a player's rating based on results against other players that they've actually played against. They don't make any explicit attempt to extrapolate a player's performance based on how that player's performance compares against other players that their opponents have played (but whom the player under consideration has not played).

You can find a description of the US Chess rating system here, which describes the computations that are done to adjust a player's rating after an event in which they've played.
> 4 votes

---
Tags: rating
---


# Question
Title: In the evolution of chess, was there ever a version in which any piece could capture a pawn en passant?
Relevant similar question:

Why can't a piece (that isn't a pawn) capture en passant?

Question:

When the game of chess evolved differently in various regions, was there any case in which the addition of the pawn's double move was accompanied by a variation of the en passant capture rule that enabled any piece to capture the pawn in the square it "skipped" over rather than restricting that capture only to opposing pawns?

(Not to be confused with the similar but orthogonal question, Is there a variant in which any piece can be taken 'en passant'?)

# Answer
No. Such a thing makes no sense and so hasn't been done in regular chess.

Pawns can only move forwards, either straight ahead or diagonally forwards. Hence the need for an en passant rule when the rules were changed to allow pawns to move two squares on their first move. All the other pieces can move and capture backwards. Hence a pawn moving two squares in one turn does not escape the possibility of capture by another piece so such a move would have no rationale.
> 1 votes

---
Tags: history, en-passant
---


title: Playing f6 against a London

text:
# Question
Title: Playing f6 against a London
I have a question about playing f6 into a London system, it is said to be a good move here:  and i understand it, you threaten e5 which is annoying for white.

But why is it not a good move here:  engine says they would play c4 (but they could do it too in the other situation)

So I'm a bit lost as to what differs between the 2, sure there is more protection on e5 by the knight, but is that enough? e5 dxe5 fxe5 Nxe5 and even though I lost a pawn, I have a center pawn and they don't, which is supposedly very much in favour of Black (very much might be exagerated but you get my point).

And also, in the first situation, they can still go Nf3 after you play f6.

# Answer
> 8 votes
In d4-d5 openings, when one side plays f3 or f6 in order to build a big center, it's often a good idea for the other side to play c5 or c4 immediately to strike their center before it overwhelms you. If dxc is played, then after Bxc it comes with check (or prevents your opponent from castling in the first place). Your opponent is no longer able to get two pawns uncontested in the center. If dxc is not played, then the d pawn probably requires more protection. Once again they are dissuaded from getting in their desired e4 or e5 move and taking over the center.

This situation often comes from a Queens Gambit Declined Exchange variation, where white plays Nge2 and f3-e4, the so-called Botvinnik or Kasparov plan. Black is usually quick to play c5 to challenge this plan directly.

```
[FEN ""]
1. d4 Nf6 2. c4 e6 3. Nc3 d5 4. cxd5 exd5 5. Bg5 Be7 6. e3 c6 7. Bd3 Nbd7 8. Qc2 O-O 9. Nge2 Re8 10. O-O Nf8 11. f3

```

Now let's compare your two positions. In the first case, white has already played c3, so playing c4 so soon afterwards would be a waste of time. Moreover, white does not have a lead in development and their king is quite far away from castling, so wasting time on pawn moves will not give them an advantage.

In the second case, white has a lead in development and is a lot closer to kingside castling than black. That means that they want to blow open the center and try and prove these two dynamic issues matter more than any static advantage black might create by getting two pawns in the center. For all of the above reasons, this is exactly the type of situation where c4 is 100% called for.

---
Tags: london-system
---


# Question
Title: Does SCID have a way of showing the top 2 engine moves?
At the moment, the Analysis window shows over 32 variations in a random order of strength.

Is it possible to just show the top 2 strongest moves?

If I right click in the window all the moves disappear and I get some text saying "Click here to see moves".

If I click on the "Click here..." text nothing happens.

If I right click again, I get 1 variation.

If I hover over the `1` drop down at the bottom I get a tooltip which is displayed off screen so cannot be read.

Eventually more variations appear but they all seem to be based around the strongest move.

# Answer
In your analysis window, you will see a toolbar up top that looks something like the following. If you change the number (the 1 at the right-hand side of the picture), you will be able to vary the number of top variations you see.
> 1 votes

---
Tags: scid
---


# Question
Title: Play a chess game so that at the end you can start a game of checkers
Yes, it *is* silly.

So you begin at the normal starting position and help-play until Black is mated (White shall have the last move since Black begins in checkers) and the mating position looks like the starting position of checkers, with any remaining piece acting as a checkers piece.

I *do* have a solution but of course the shortest one wins.

# Answer
I have found another solution, 25 plies.

```
[FEN ""]
[startply "25"]

1. a3 b6 2.Nc3 Nh6 3. Nd5 d6 4. Nxb6 axb6 5. c3 f6 6. e3 Kf7 7. g4 Nxg4 8. Bd3 Nxh2 9. Bxh7 Bg4 10. Bg6+ Kxg6 11. Qxg4+ Kh6 12. Qg3 Ra7 13. Rxh2#

```
> 5 votes

# Answer
Here is a proposition in 29 plies.

```
[FEN ""]
[startply "29"]

1. Nc3 b6 2. e3 Bb7 3. Ne4 h5 4. g3 Bxe4 5. Bd3 h4 6. Bxe4 hxg3 7. Bxa8 gxh2 8. a3 Nf6 9. c3 Nd5 10. Bxd5 f6 11. Bf7+ Kxf7 12. Qf3 d6 13. Qf4 Kg6 14. Qg3+ Kh6 15. Rxh2#

```

We can probably save 2, 4, or 6 plies on the way.
> 8 votes

# Answer
Arriving at 28. Na1#

* a1=N, 5 moves incl. the mating move Na1#;
* a3=R, 2 moves incl. pushing a-pawn;
* b2=Q, 3 moves incl. pushing c-pawn;
* c3=R, 6 moves incl. 0-0, excl. Q-clearance, see above;
* c1=B, 2 moves (clearance for Rfc1);
* d2=p, -
* e1=N, 1 move, excl. 0-0, see above
* e3=p, 1 move
* g3=p, 0 moves (accounted for in c3=R).

Got another 8 moves for pushing b-pawn, recaptures on the queenside and g2 as well as preparing Na1# discovered mate tempowise. Rather confident though that this can be done more efficiently.
> 2 votes

---
Tags: problems
---


# Question
Title: Do modern chess engines learn material values through self-play?
I have a simple question about how Chess engines like Stockfish and Leela value material. Do they use traditional material values (i.e. 1 for pawn, 3 for knight/bishop, 5 for rook, 9 for queen), or do they learn their own values through self-play?

This question (What relative point values of pieces do engines use?) suggests that Stockfish has unique material values, which are defined explicitly. However, those values appear hand-tuned, not learned. Would learned values potentially deviate greatly from our standard piece values?

# Answer
As the answer you linked elaborates: "As you might guess, these numbers are empirically tuned."

In practice this often boils down to self play. Traditionally you'd roughly speaking try different material values and see which ones perform best in a tournament that has different versions competing.

Now with NNue for Stockfish, and the NNs in Leela things go one step further, they don't explicitly have material values at all anymore but rather evaluate the position as a whole. (though I suppose the piece values still have use for Stockfish in search heuristics etc.)
> 7 votes

# Answer
No. To be more precise, the inputs to the neural networks are high dimensional "planes". The paper https://arxiv.org/pdf/1712.01815.pdf has the representation:

> The input to the neural network is an N × N × (MT + L) image stack that represents state using a concatenation of T sets of M planes of size N × N. Each set of planes represents the board position at a time-step t − T + 1, ..., t, and is set to zero for time-steps less than 1. The board is oriented to the perspective of the current player. The M feature planes are composed of binary feature planes indicating the presence of the player’s pieces, with one plane for each piece type, and a second set of planes indicating the presence of the opponent’s pieces. For shogi there are additional planes indicating the number of captured prisoners of each type. There are an additional L constant-valued input planes denoting the player’s colour, the total move count, and the state of special rules: the legality of castling in chess (kingside or queenside); the repetition count for that position (3 repetitions is an automatic draw in chess; 4 in shogi); and the number of moves without progress in chess (50 moves without progress is an automatic draw). Input features are summarised in Table S1.
> 1 votes

---
Tags: engines, point-value
---


title: Why this game is a draw?

text:
# Question
Title: Why this game is a draw?
Chess.com gives a draw result. I can't understand why.

# Answer
Black has no legal move, which is an automated draw by design. Every move at Black's hand would result in its king in check.
> 4 votes

---
Tags: draw
---


# Question
Title: What is the difference between TPG and Tournament Performance Rating?
wI understand "Tournament Performance Rating", but I have seen a Web calculator that also has TPG. What is the difference between them and why are both used?

# Answer
> 2 votes
https://www.englishchess.org.uk/Juniors/tournament-performance-calculator/

"The tournament performance grade (TPG) commonly used in the ECF grading system is calculated on a different basis than a TPR. Junior selection TPGs, however, are essentially TPR calculations using FIDE ratings that correspond to ECF grades."

---
Tags: rating, tournament
---


title: Hamppe-Meitner, the final verdict?

text:
# Question
Title: Hamppe-Meitner, the final verdict?
```
[FEN ""]

1.e4 e5 2.Nc3 Bc5 3.Na4 Bxf2+

```

For those of you who never heard of Hamppe-Meitner. Now I dimly remember that a super engine somewhere found a White win, but even the bringer of the news ceded that a super-duper engine could reverse that. (See e.g. here for the complete game and how they still discuss...)

Can you link me to a human-annotated (a mere list with cryptical "+0.5 after Kj9" is quite useless, see below) computer analysis, also *with* evaluations of the side variants? Mustn't be each and any move, but at least the sensible ones, if one can talk of sensible in that crazy positions...)

The greater plan is to turn it into a Euwe-style "I test myself" test for the chess kids I train, to boost their imagination. Of course I must deliver when I get asked why Kj9 botches the draw!

# Answer
You might want to go with http://www.kenilworthchessclub.org/games/java/2009/hamppe-meitner.htm however no guarantees on its being up to date.
> 3 votes

# Answer
Using Stockfish 14 at depth up to 25 I find:

```
4 Kxf2 (Ke2? Bxg1! 5 Rxg1 d5 {-6.3}) Qh4+
5 Ke3 (g3 Qxe4! 6 Qe1/Qe2 Qxh1 7 Qxe5+ Kf8
  (Ne7? 8 Nf3! {+1.3}) 8 Bg2/Qxc7 {-0.2}) Qf4+
6 Kd3 d5
7 Qe1 (Kc3 d4+ 8 Kb3 Qxe4 {-0.9} (Be6+? 9 c4! {+0.4})) Nf6
8 g3 dxe4+ (Qg4 9 c3 {+0.1})
9 Kc3 Nd5+ 10 Kb3 Qf6 11 c4 b5 (Nc6)
12 cxb5 (cxd5? bxa4+! {-0.9}) Nd7 {-0.7}

```

```
[fen "rnbqk1nr/pppp1ppp/8/4p3/N3P3/8/PPPP1bPP/R1BQKBNR w - - 0 4"]

4. Kxf2 (4. Ke2? Bxg1! 5. Rxg1 d5 {-6.3}) Qh4+ 5. Ke3 (5. g3 Qxe4! 6. Qe1 (6. Qe2 Qxh1) Qxh1 7. Qxe5+ Kf8 (7...Ne7? 8. Nf3! {+1.3}) 8. Bg2 (8. Qxc7) {-0.2}) Qf4+ 6. Kd3 d5 7. Qe1 (7. Kc3 d4+ 8. Kb3 Qxe4 {-0.9} (8...Be6+? 9. c4! {+0.4})) Nf6 8. g3 dxe4+ (8...Qg4 9. c3 {+0.1}) 9. Kc3 Nd5+ 10. Kb3 Qf6 11. c4 b5 (11...Nc6) 12. cxb5 (12. cxd5? bxa4+! {-0.9}) Nd7 {-0.7}

```

Figures are evaluations in terms of advantage to White in pawns. These are rough --- different evaluations might give slightly different figures.

If there is a line by which White can guarantee a winning position, Stockfish can't find it at that depth. I get the impression that Stockfish reckons that Black has a slight advantage.

365chess.com's openings-database rates 3 Na4 Bxf2+ at -1.00, and says that it is very rare: only 28 3 Na4 games of which 24 are 3 Na4 Bxf2+, compared to 551 for 3 Bc4. Game totals are of games in its big database.
> 3 votes

# Answer
I'm not completely sure about your question, but if you're trying to find a win for one side in the game, there were 5 critical positions, 2 for black and 3 for white, in which they could have won the game.

Black initially had a critical position after 7.Kc3 and could have responded with the winning d4+.

Black plays 7...Qxe5 instead, giving white a winning position after white plays 8.d4.

White blunders back, playing 8.Kb3, allowing black to win after he plays 8...d4.

White is also winning after Black played 8...Na6 after 9.d4.

Lastly, after Black played 11...Nc5+, White can win with 12.Kb5.

Four of the five critical positions in this game revolve pushing the pawn to the d4 square.
> 0 votes

---
Tags: engines, analysis, draw, annotation, reference-request
---


# Question
Title: Did Lichess Level 8 truly lose this game?
Jonathan Scrantz played this game against Lichess Level 8:

```
[Title "Jonathan Scrantz VS Stockfish Level 8 (3000) after 9. Kh1"]
[FEN ""]
[Startply "17"]

1. e4 e5 2. Bc4 Bc5 3. b4 Bxb4 4. f4 exf4 5. Nf3 Be7 6. d4 Bh4+ 7. g3 fxg3 8. O-O gxh2+ 9. Kh1 d5 10. exd5 Bh3 11. Nc3 Bxf1 12. Qxf1 Bf6 13. Ba3 Ne7 14. Ne4 O-O 15. Nxf6+ gxf6 16. Bxe7 Qxe7 17. Bd3 Qd7 18. Qg2+ Kh8 19. Bxh7 Qxd5 20. Qh3 Kg7 21. c4 Qa5 22. Qg2+ Kh6 23. c5 Rh8 24. Nh4 Qxc5 25. dxc5 Kh5 26. Nf5 Rxh7 27. Rf1 Rg7 28. Qxg7 Na6 29. Rf3 b6 30. Rh3#

```

I am aware that Lichess Level 8 deliberately makes mistakes, but I wonder whether it really did so in this game or not. It seems to me that `12. ... Bf6` was the definitively losing move. But SF10+ on that position at depth 24+ thinks that `Bf6` has score `+1.9` compared to `+1.3` for `Be7`, so did Black already have a losing position before move 12? If so, where is the first point at which Black made a clear mistake and what is the general (human) strategy for White to win from that point?

# Answer
> 1 votes
Black had a losing position after 7...fxg3. The best way for black to go for a draw at this point was to play 7...d5, which continues 8.Bxd5 fxg3 9.O-O Nf6 10.Ba3 gxh2+ 11.Kh1 Nxd5 12.exd5 Qxd5 13.Nc3 Qa5 +=.

There are two possible continuations for black after 8.O-O, which are 8...d4 and 8...gxh2+, that may not seem initially bad, but are completely losing. I've detailed those in the following study: https://lichess.org/study/URz9uXJd

Please ask me any further questions if your confused.

---
Tags: analysis, strategy, stockfish, positional-play, sacrifice
---


title: Reviewing Chess Tactics Puzzles

text:
# Question
Title: Reviewing Chess Tactics Puzzles
Is there somewhere online I can play chess tactic puzzles and redo them whenever I want? I do tactics on lichess but it doesn't store my puzzles. Is there somewhere that stores all my tactic problems so I can redo them? I feel that would be better to develop pattern recognition. Thanks in advance.

# Answer
If you have a premium membership on ChessTempo, you can create problem sets with spaced repetition, which is one of the advanced options under problem search. If you select this option, the site will show you both new puzzles and puzzles you've already solved. You'll see puzzles you've gotten wrong more often, and if you get a puzzle right a few times, you won't see it as much.

Lucas Chess, which is a desktop program and free to download, also includes sets of tactics puzzles for training using spaced repetition.
> 2 votes

# Answer
I don't know of a specific tactics site that stores all your previous puzzles so that you can redo them. However, to develop pattern recognition you don't need to do the exact same puzzles over again - doing different puzzles with the same type of tactic / concept is just as good or better.

It's better to get a variety of examples for one tactic / concept, since it would cover more of the possibilities you can face in a game. Just doing a few puzzles many times wouldn't be as good, since it doesn't cover enough of the types of positions you may run into during a game.

If you want to see full solutions immediately after you get a puzzle wrong, try Chess Tempo. It shows you the full solution after you finish and let's you play through it.
> 0 votes

# Answer
I do problems on Lichess, and they do save at least the last 15 that you've done. There are little boxes for each of these in sequence under the current problem diagram that you can click on to bring up the old problem diagrams. The boxes are either green or red according to whether you have solved or failed the problem.
> 0 votes

# Answer
As Larry Coleman Said, a premium membership on ChessTempo will allow you to do that. I would like to add that Lichess also implemented this feature in 2016. Without you knowing it, it repeats problems that you got wrong until you get them right. See this blog post
> 0 votes

# Answer
Our site https://xakemate.eus offers this option when registered
> 0 votes

---
Tags: tactics, training, puzzles
---


# Question
Title: Is there any (free) online tool for calculating Glicko-2 ratings after a game?
I am looking for a tool where I can input the Glicko-2 ratings of 2 players and the result of the match (1–0, 0–1 or draw). Also, the rest of the Glicko-2 parameters, i.e., each player’s rating deviation and volatility (σ), and the system constant (τ). Then, the tool will tell me what the ratings of the players will be after the match (and their new rating deviation and volatility).

There are already similar free online tools for Elo. E.g., Elo Calculator by Omni Calculator.

I am aware of code implementations of this, as well as an Excel calculator, but I am looking for an online GUI tool.

# Answer
> 2 votes
This is now published in streamlit share

#### Calculation #1

#### Calculation #2

---
Tags: software, rating, glicko-2
---


# Question
Title: Chess.com daily puzzle question (Gruenfeld's endgame magic)
In today's chess.com daily puzzle, I have no idea why the first move of the solution makes sense.

```
[fen "8/8/8/pp6/P7/7K/1k6/R7 w - - 0 1"]

```

The first step in the suggested solution is **Ra3**. I do not see how that beats **axb5** (which is the second move anyway).

Can anyone explain why to me?

# Answer
If you play out the moves you will see that axb5 leads to a draw because white can never drive the black king away from the pawn with just the queen and using the king leads to stalemate or black also queening. Rxa3 leads to a win because white queens with check and the black pawn can never get to a2 creating stalemate chances.

```
[fen "8/8/8/pp6/P7/7K/1k6/R7 w - - 0 1"]

1. Ra3 (1. axb5 Kxa1 2. b6 a4 3. b7 a3 4. b8=Q a2 5. Qh8+ {any king move is stalemate} Kb1 6. Qh7+ Ka1 7. Qg7+ Kb1 8. Qg6+ Ka1 9. Qf6+ Kb1 10. Qf5+ Ka1 11. Qe5+ Kb1 12. Qe4+ Ka1 13. Qd4+ Kb1 14. Qd3+ Ka1 15. Qc3+ Kb1 16. Qb3+ Ka1) Kxa3 2. axb5 Kb2 3. b6 a4 4. b7 a3 5. b8=Q+ Ka1 {Kc2 is the same White threatens the pawn and black must defend} 6. Qe5+ Kb1 7. Qe4+ Kb2 (7...Ka1 8. Qc2 a2 9. Qc1#) 8. Qb4+ Ka2 9. Kg2

```
> 10 votes

---
Tags: puzzles, chess.com
---


# Question
Title: Why don't we see more Kings Indian Defenses in top level chess?
One of the most interesting openings, in my opinion, is the Kings Indian Defense (KID). 2-4 decades ago it used to be very popular at the top level with Bobby Fischer and Garry Kasparov using it regularly. Even a few years ago it used to be quite popular with Radjabov and Nakamura having it in their repertoires.

Why has it started to go out of fashion at the elite level, and especially with the Neural Network engines on the rise? Leela has been able to use it quite effectively. Nakamura said in an interview that the Kings Indian is lost for black. What are the drawbacks of the openings that prevent it from being seen at the top level?

**The Interview is from 2015 Sinquefield cup after Hikaru obliterated Wesley So with the Kings Indian**

# Answer
> 10 votes
It is simply not as solid as other openings, mostly because it cedes too much space, and especially with the advent of computers: White has simply found more ways to press black.

In a 2017 interview, Magnus Carlsen did not think too highly of it. "If he had wanted a worse position, he would have played the King’s Indian," Carlsen said.

Nevertheless, it still gets played at the highest level from time to time, probably mostly as a surprise weapon. Here is a recent search of Mega 2020 (I previously searched incorrectly, and have edited this). This is from 2015-2020, sorted by rating first, and then date. You can see that despite the quote above, even Carlsen has played it.

# Answer
> 5 votes
Nakamura is known to run at the mouth. KID is certainly not losing.

Chess in general at the top level is more solid; Berlin's instead of Sicilians. It is just a trend.

Notice how Carlsen wasn't dominating with double-king-pawn as Black, but when he prepared the Sveshnikov his score soared. People thought they could go after his Sicilian... It's the same with the King's Indian. Radjabov is the top KID proponent and he does very well, but at the top they don't want to play 35 moves of book. They are more about minute edges in the endgame and that is not in the spirit of the KID.

Having said that, there is ton's of theory which make it not fun for Black. The Bayonet attack doesn't let Black try to mate White while White wins on the Queen-side in a bunch of other mainlines.

**UPDATE:** Firouzja is playing the KID right now in the Prague Chess Festival; would a 2700 player play it if he thought it was losing?

# Answer
> 3 votes
I need to make a correction to the original post, and then I will provide an answer!

The question-asker claimed that Hikaru said that the King's Indian lost for black. This is actually not true! If you click on the link provided, you'll find that Hikaru states that Garry Kasparov decided that the King's Indian loses for black. And when Hikaru stated that, he did not intend to say that that was his opinion. Rather, he was answering the question from the interviewer who wondered if Garry had shared secrets to Hikaru that Hikaru was holding back. Hikaru responded by saying that he wasn't holding back secrets passed on by Garry, since Garry had decided it was losing. That was his point.

Now, obviously, with the tone in which Hikaru said this (and Hikaru's other comments), it was obvious that Hikaru was starting to sour on the opening a bit himself. But the King's Indian is a risky opening that is difficult to play well at the highest level -- and Hikaru probably had gotten burned by it recently.

However, that interview was from a long time ago.

Hikaru is well known (as are all chess players and all human beings) for taking different tones and attitudes toward something that backfires on them.

This by no means signifies that he is done with the King's Indian.

In fact, Garry Kasparov and Judit Polgar had turned away from the King's Indian, but Hikaru himself and Radjabov revived it.

At that point in time in 2015, the King's Indian may have been having troubles again -- but that doesn't mean that it won't be revived again.

The difficulty is that computers keep advancing and making it tough to play incredibly sharp lines without a clear outcome.

Players are always unsure whether or not their opponent has some tricky line prepared after hours of computer analysis. As such, they tend to like slightly safer lines.

But the real answer to your question is simply that openings go in and out of favor. Generally, when one really good player has success with an opening, it causes the other players to look into it more -- and it might even spark new ideas in their minds.

It's like a conversation. I might say something that causes you to go "Oh, wow, that's a great idea. And if that's true, then isn't such and such true?"

Right now, nobody in the top level are sparking those sorts of ideas in the King's Indian.

So, the King's Indian "conversation," has died off a bit.

That doesn't mean it won't be revived in the future!

(and regarding Magnus' remark, Magnus has his opinions... and he was also being witty!)

# Answer
> 2 votes
While the KID is a good opening if you want an exciting game and good winning chances as black, these benefits come at a cost. The KID is not a solid opening when compared to many other ways for black to meet queenside pawn openings from white, and there is a wide variety of tricky lines that white can choose from to try for a serious advantage out of the opening.

Some of these setups by white are very sharp, forcing black to know a huge amount of concrete lines by heart not to immediately fall into a lost position (I'm thinking mainly of the various ways to play the Mar del Plata variation for white, including - but not limited to - Kramnik's dreaded bayonet attack)

Other setups are more strategic in nature, trying to utilize the space advantage that black hands over in the beginning of the game. In this list, we include the Sämisch, the Petrosian, and the Makogonov systems (not to mention the various fianchetto systems that white can try, which is another can of worms that black has to deal with). All of these systems pose serious strategic problems for the black side, and black needs not only a solid understanding of the arising position, but must also know a ton of spectacular "only moves" to defend properly (see the game between Svidler and Griscuk from the candidates 2013; if Grischuk hadn't played the seemingly outrageous 12...Nxc4! he would have found himself in deep, deep trouble).

If you want a good indication of how much effort and time a top level player would need to put in to play the KID consistently with confidence, you may want to look at the book series "Kotronias on the King's Indian". In this series, Kotronias needs more than 2000 pages of concrete analysis to demonstrate that there is no clear refutation to the KID.

With all this being said, the KID is certainly not a bad opening (a claim supported by the analysis done by Kotronias). But the problem with playing it at the highest level is that black is risking a lot when playing it, and would be risking even more by including it in their main repertoire (leaving themselves open to some seriously nasty preps by their world-class opponents; this is something that MVL does by only playing his absolute pet Najdorf and Grünfeld against basically anything, and sometimes he suffers for it). Therefore, most players at the top level who are comfortable playing the KID only use it as a surprise weapon (or if they're playing shorter time controls), or if they're in a must-win situation where the difference between a draw and a loss is irrelevant.

---
Tags: opening, master-games, kings-indian
---


title: Neurons Stockfish NNUE

text:
# Question
Title: Neurons Stockfish NNUE
I am referring to this picture.

What do the individual neurons in the ANN do? Do they represent criteria for the evaluation, like for example material, pawn structure, king safety and so on?

# Answer
I will extend a bit on Scounged's comment, which in principle suffices as an answer.

Indeed, each neuron is nothing more than a little funtion computer that takes all inputs, multiplies them with a weighting, and "fires" if the resultat is above some level (e.g. by a sigmoid, but 0/1 would work as well - anything nonlinear works).

The ineffability of NN always has been a main criticism against them. It is typical "emergent" behavior, and any NN that is large enough can no longer be split into sensible sub-units, even if the emulated function can. (It is very possible that a NN that simulates the KR/K mating technique is still simple enough for such an analysis.)

"Understanding NN" is cutting-edge research. "Understanding" as in "understanding the math behind it" is common knowledge and accessible to anyone with average math and computer science abilities, but "understanding" as in "understanding how it solves a task" is difficult.

It would be an interesting experiment to kill a specific neuron of Leela and see what happens, but I bet you could kill a specific neuron in *my* brain and nothing will happen to my ELO. Specifically, I do *not* expect that Leela suddenly neglects king safety, since Leela already has too many neurons.
> 4 votes

---
Tags: stockfish
---


# Question
Title: Rook move and back rank after kingside castling in the queens gambit accepted
I'm about 1500 on Lichess, and as white I almost always play the queens gambit accepted (if reached).

After some moves I often, almost naturally, play at some point Rfe1 and h3.

The first one is to get my rook away from the f pawn to a semi open file. The h3 push is because I'm always afraid of back rank mate so this prevents this. Also it stops black from playing bg4 pinning my usually unmoved queen.

Are these good reasonings/strategies?

# Answer
> 1 votes
There's too many variables to give a definite answer.

If white has a pawn on e3, the queen belongs on e2 so the king's rook can get to d1. If white's e-pawn is gone, then that rook belongs on e1 to support a knight on e5. There are some lines where the rook is left on f1 to support the f-pawn when it is pushed to f5, normally when black's bishop is on b7.

As I can't remember any variation without a pawn on e6, I don't understand any need to prevent the pin. I rarely find white needing to worry about any aggression from black, let alone a back rank mate. I find that h3 is a wasted tempo which is better used for an aggressive move.

I suggest you ask this in the lichess.org forum with diagrams to help clarify your plans. That site also has some good studies to show you middlegame plans in the QGA.

---
Tags: strategy, queens-gambit
---


# Question
Title: What are considered the squares a piece attacks?
Take a look at the following text taken from "Logical Chess" by Irving Chernev. What are considered the squares a piece attack? How are the queens attacking 9 compared to 5 and the bishops 13 compared to 7?

# Answer
Chernev is using the word "attack" to mean the squares that piece could move to on the next move. That includes empty squares and squares occupied by enemy pieces. He clearly feels slightly ambiguous about his usage because he also uses the word "control" to mean the same thing when talking about the bishops.

So, for the black queen:

* it can move to b8, c8, d7, d6
* it attacks the piece on e5.

That makes a total of 5 squares it is also protecting pieces on additional 5 squares.

For the white queen:

* it can move to e1, f1, d2, d3, e3, f3, e4, g4, h5
* it is not attacking any black pieces

That makes a total of 9 squares. It is also protecting pieces on an additional 5 squares.

The same calculation can be made for the bishops. The point Chernev is making, before the days of engines, is that white's pieces are more mobile. They can go to more squares. Nowadays engines often use that kind of measurement to make small adjustments in the values it assigns to the pieces but it featured in the evaluations of top players long before the era of engines..
> 17 votes

# Answer
It's just the number of available moves, regardless of their quality.
> 8 votes

---
Tags: attack
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# Question
Title: Is there a tournament system that pairs players based on ratings being similar?
Clearly games are more fun when the result can't be predicted in advance hence pairing players who have not recently played each other and have similar ratings has advantages. After a few games it should be possible to pair based on each player's tournament rating. (It would also be possible to have rules to maximise how often masters are paired with non-masters with similar strengths.)

Maybe alternate between a rating difference that is large enough that a draw is a good result for the lower rated player and a difference that is small enough that a draw is expected.

Such a tournament would not need any limits on the rating of players, but somehow prizes will need to be allocated so people at all ratings have an incentive to play as well as possible.

# Answer
> 8 votes
Swiss tournaments somewhat attempt to do what you want in their later rounds. Also, tournament organizers often have different ratings-based sections for larger Swiss events to reduce the number of games played with large ratings differences. However, I expect you are aware of this and are looking for other systems.

Perhaps the closest is the "*Quad*", if this fits your idea. It is somewhat common in the United States (at least the mid-Atlantic with which I am familiar), although I don't know how often it's played elsewhere. Each entrant plays three games in what are (seemingly) always one day events.

In a quad the players are split into groups of four, based on ratings: the top four rated players are in one quad, the next four in a second quad and so forth. Each quad then plays a round robin (i.e. everyone plays one game against each of the others in the quad). Typically only the winner of a quad wins prize money; in the case of ties the prize money is split.

When the number of entrants isn't a multiple of four the lowest rated group will have a number of entrants other than four - I've seen groups of three, five, or six used when that happens. A Swiss format is used for a "quad" with more than four players.

Of course, there can still be large rating disparities if there are insufficient numbers of entrants with ratings in close ranges. Unfortunately, that is unavoidable when there aren't many players and there is a large difference in ratings.

# Answer
> 5 votes
I want to give an unequivocal "No" as the answer, but that's too simple. General Swiss pairing rules (for where you want to find a winner from lots of players / teams and few rounds / matches) require you to *not* pair like that but there can be exceptions.

Let's start by looking at FIDE's Basic rules for Swiss Systems. It's mostly about the principles for a way to do fair pairings. The closest it comes to matching players with similar ratings is:

> e In general, players are paired to others with the same score.

So, if players with similar ratings play at about the same level then after a few rounds they are likely to end up on similar scores and end up paired against each other but in general that doesn't happen most of the time kind of by design as we see next.

FIDE's General handling rules for Swiss Tournaments goes into more detail and makes it clear how pairing similar rated players is *avoided*:

> 2 Before the first round the players are ranked in order of, respectively
>
> Strength (rating)
> FIDE-title (GM-IM- WGM-FM-WIM-CM-WFM-WCM-no title)
> alphabetically (unless it has been previously stated that this criterion has been replaced by another one)
>
> 3 This ranking is used to determine the pairing numbers; the highest one gets #1 etc.

This is key. When the pairing is done the first step is to split the players into score groups (you play against someone with the same or similar score) then each score group is split in two according to number of blacks and whites to try and ensure fair numbers for the players. Then in each score group and colour the groups are split in two according to their initial ranking and the high white group is paired against the low black group and vice versa. This pretty much guarantees mismatches in the early rounds in big fields.

This is done to ensure fairness in general, to give the best chance of fairly finding the best players according to how they play and to try and make the key pairings (between the players playing best) happen in the later rounds when they have a clearer idea of what they are playing for.

However there is one case in which these rules can be bent towards pairing players of more similar ratings against each other.

**Acceleration**

If a Swiss tournament has enough strong (IMs, GMs, WGMs, WIMs, FMs, WFMs etc) players from enough different federations then players who do well enough can achieve a title norm (IM, GM, WGM, WIM, etc.) If such a player has to play a weak player in round 1 and maybe also in round 2 then this lowers their average performance rating over the tournament and can decrease the chances of achieving a norm if there are too many weak players.

The solution to this is to use *accelerated pairings*. The details are spelled out in FIDE's FIDE-approved Accelerated Systems.

The basic method is to split the initial ranking of the players into two groups, the top half rated players and bottom half rated players, and to give all the players in the top group one or two "fictitious" points for the first two or three rounds, pair as normal and then remove the fictitious points after the two or three rounds of "acceleration".

This means that the two groups will end up playing within their group against more similarly rated opponents. Within the two groups they are still ranked and paired according to rating (after score) so this reduces the rating disparity but doesn't eliminate it.

# Answer
> 2 votes
I believe you are looking for the Monrad system. This is a variant of the Swiss system in which, in each round, players are grouped by score and then listed in order of descending rating (or seeding), as in the more familiar type of Swiss tournament (otherwise known as the "Dutch system"). But, instead of pairing the top half against the bottom half, it instead pairs the first player against the second player, third player against the fourth player, and so forth. It does make allowances for modifying pairings to ensure, for instance, that no player faces the same opponent more than once in an event. If you don't care about avoiding repeat matchups, then a further variant of that called the Danish system does exactly that - it pairs players as described above, without regard to whether they've been paired earlier in the event. Either way, this method of pairing makes it more likely that, in each round of an event, players are more likely to face an opponent of similar rating (or similar seeding in the tournament).

One of the big disadvantages to doing it this way (in my opinion) is that, particularly in a larger event, it can put substantially lower rated players in contention for a share of the same prizes being contended for by much higher rated players, without ever having any of those lower rated players face an opponent rated substantially higher than themselves. So (just as an example) you might find that a player rated 1200 could end up in a position where they might be able to split first prize with a player rated 2200, simply because they have the same number of points at the end of the event - even though the 2200 rated player had to work a lot harder than the 1200 rated player in order to get those points. Whether you think this is fair or not kind of depends on your goal - do you want the prizes to be awarded to the players with the strongest performances in the event (taking into account the strength of their opposition), or to you want the prizes awarded to the players who just accumulate the most points in the event (without regard to the strength of the opponents they faced)? Either goal could potentially be valid.

# Answer
> 2 votes
Go tournaments commonly use the McMahon system, which is basically like Swiss, but the players are given different amounts of points (wins) beforehand for free, based on their rank/rating. In a way, it can be considered a Swiss tournament where the first few rounds are only simulated, except that the initial scoring is usually not actually done like that, but directly on ratings.

With winning the tournament being based on the score (wins) gathered during the actual games, and the initial score, this means that it's impossible for players outside the top group to win the tournament. Hence, it should only be used in cases where there skill levels of contestants vary enough that it's possible to identify beforehand some skill level below which a contestant would already be very unlikely to win the whole tournament anyway. Or in other words, the top group should be set so that everyone who just might be capable of winning should be in it.

Like in Swiss, N rounds are needed to find winner from a top group of 2^N players. (And more rounds can bring confusing results, e.g. with a top group of 16, a five-round tournament may end up with two players in the top group finishing with 4 wins each.)

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Tags: rating, fide, tournament, swiss-pairing
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# Question
Title: Do engines have a larger advantage over a human at long or short time controls?
**Question:** Title question, basically: do engines have a larger advantage over a human at long or short time controls? Have any studies been done on this?

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**Context for the question:** On a reddit thread yesterday someone pointed out that Andrew Tang beat Leela in an ultrabullet game around four years ago. I was astounded by this -- I would not have thought this possible. (Leela was rated around 3250 on Lichess at the time, so she had been trained quite a bit there) I mentioned this to a buddy of mine, and his contention was that humans will perform better against engines at shorter time control. I thought that was flat out wrong, but set out to prove that point.

Unfortunately, I was not able to find much in the way of hard data. This best I could find was this experiment done by the folks (guy?) who runs FGRL that compares search depth against time. It seems that doubling the amount of thinking time approximately increases the search-depth by 2-ply. I have no idea how search-depth corresponds to playing strength -- the best I could find was this paper from 2013 that suggests that an increase in search depth of 2-ply is an increase in playing strength of approximately 120 rating points.

So, my best guess at this point is that doubling the amount of thinking time increases the engines rating by around 120 rating points. When I made the argument that engines have a bigger advantage at shorter time controls, I did not expect a 2-ply increase in search depth to increase the playing strength by 120 rating points, I expected it to be considerably lower.

Grandmasters also play exceptionally well at short time controls. How much do they gain by doubling the time. Is it 120 rating points? I don't know. Do you? This is what made me doubt my initial conclusion, and prompted this question.

Is the 120 rating point increase in computer playing strength by doubling its thinking time a reasonable conclusion?

# Answer
> 2 votes
Historically, the answer is "no". Computers beat humans at blitz well before they beat humans at classical chess (example).

Humans seldom play serious matches with a time handicap, so I'm not aware if there are statistics on how much elo a player gains by having 120 more minutes. With computers, the allocated time is less important than the depth it searches to - the difference between letting a computer think for 2 days vs. 1 day per move is much smaller than letting a computer think for 10 seconds vs. 5 seconds per move.

If you look at depth, then the elo gain with increasing search depth is tremendous. It depends on the engine, but an order of magnitude estimate for going one move deeper is a couple hundred elo.

# Answer
> 1 votes
This is kind of hard to answer because of how much better computers are than humans at all time controls, but according to https://chesspro-ru.translate.goog/guestnew/looknullmessage/?themeid=54&id=15&page=24&\_x\_tr\_sl=ru&\_x\_tr\_tl=en&\_x\_tr\_hl=en-US&\_x\_tr\_pto=wapp, there was a 100 game match between SF11 and Fruit, where SF had 8 seconds per game + .04 seconds per move compared to 140 minutes per game + 40 seconds per move for fruit. With these settings, SF was about 150 elo stronger than fruit, which is roughly super-GM strength. Since then, SF has gained approximately https://github.com/official-stockfish/Stockfish/discussions/3628#discussioncomment-1047728, so SF at 1/4th second per game should be roughly the same strength as Magnus at a few hours per move.

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Tags: engines
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