# Question
Title: Is Colle-Zukertort a good way to improve beginner play?
I'm still trying to improve my repertoire and building more towards aggressive openings which I find to better fit my playing style.

Colle-Zukertort seems like a popular one and I've seen it recommended a couple times for beginners.

What are your thoughts on this, should I really include this as part of my regular play? Are there some other moves I could add to this to make my formation more robust?

# Answer
> 25 votes
The Colle is definitely not an aggressive opening in the classical sense. If you like the positions that you get with the Colle, by all means, play it to your heart's content.

The Colle is a very conservative opening because white plays d4 and then really doesn't make any other moves to occupy the center. Playing for theoretical equality as white might be okay if you just want to get a familiar position, but there are other openings that promise white a greater advantage, which is why top level games rarely, if ever, feature the Colle.

System openings like the Colle don't really teach you how to play chess, they teach you how to play the Colle. The reason that the Colle is recommended to beginners is that the ideas and plans are simple, and it works fairly well against any kind of play by black. White does frequently get an attack on black's kingside, which can be decisive if black does not defend accurately.

The biggest downside to the Colle is this: other openings, like e4 e5, will teach you concepts and themes that will apply to all parts of chess. For instance, how to maneuver your knights and bishops in order to improve the position. In the Sicilian (as either color), you can learn how to attack and defend - always useful. The Colle is really limited to learning how to free the dark square bishop and how to stir up an attack on h7. If black is on top of things, the attack will never come to fruition, and black will get a good game after striking with c5.

So my personal opinion if you want to win lots of games: learn the Colle, study all the possible positions, and memorize the moves. If you want to improve your chess, which will lead to more wins down the road, then play main line openings and only play the Colle occasionally for a change of pace.

---

Some common "system" openings: * Colle (`d4`, `e3`, `c3`, `Bd3`)
* Colle-Zukertort (white plays the Colle with `b3` and `Bb2` instead of `c3`)
* Stonewall Attack (`d4`, `e3`, `f4`, `Bd3`)
* King's Indian Attack (`e4`, `d3`, `g3`, `Bg2`, `Nf3`)

Notice that these openings don't try to occupy the center. By not occupying the center, white avoids confrontation until later in the game. This means that white can develop in a known fashion before initiating contact and only then follow the prescribed plans.

# Answer
> 10 votes
It looks like a reasonable system to me as the structure, and the ideas behind the moves look fairly easy to understand.

As for being aggressive, it's the type of aggression that slowly builds up with an aim towards the kingside, successfully doing this might be the hard part of this system. If you don't follow through and restrict Black in some way, there is the danger that Black could get ahead of White in activity, especially on the queenside.

# Answer
> 7 votes
Having read *The Colle Move by Move* by Cyrus Lakdawala, *Zuke 'Em-The Colle Zukertort Revolutionized* & *The Moment of Zuke* by David I. Rudel, *Killer Chess Opening Repertoire* by Aaron Summerscale, *Starting out: d-pawn attacks* by Richard Palliser, *Starting out: The Colle* by Richard Palliser, played countless blitz and OTB games vs strong players 1800+, I can categorically say that the Colle is far from a one trick pony bud.

The Zuke is not designed to open up the centre, as I have said. Sometimes it happens when the Queen is on c7 and a rook on c1, but the idea is to fix the centre with Ne5 and then attack on the kingside. That is the basic plan of the "mainline". However, in meeting moves like Bf5/Bg4, Nc6, g6, b6, you will encounter quite mainline Slav, Chigorin and Queens Indian Defences.

I think the stereotype people have towards the Colle is based on the simple old main lines of the Colle-Koltanowski variation, which is pretty much a different beast despite starting the move e3 and the Ne5 plan.

In the write up to the excellent book *Colle Move by Move* by Cyrus Lakdawala, the promo blurb says,

> White typically builds on solid foundations before unleashing an attack on the enemy king. This straightforward plan makes it particularly popular at club level, but the Colle is played successfully by Grandmasters too. Lakdawala covers both the main lines and the more aggressive Colle-Zukertort Attack.

I wouldn't suggest that the Colle Zuke or K are the greatest thing since sliced bread but they are perfectly sound, lead to some interesting attacking positions and are benefited practically by the stereotypes expressed on here. I recently played a 1900+ FIDE-rated player and they explained that since I would be looking to open the centre with e4 they played c x d when the fact is, it is almost never played in the Zuke! Just goes to show!

# Answer
> 5 votes
To answer the question at the start of the post, I would say no. The system is easy to learn and play but that won't help you to improve. You want an opening that leads to sharp tactics. I just had a game on ICC against a slightly above average player and as soon as I saw the opening I thought, ok draw. It was. White risks very little but often gains very little. I was happy with a draw with black against a slightly higher rated player, but honestly I don't think I learned anything or feel like I was pushed, just traded things off and offered a draw. If you want to beat up your friends in chess games then you need to know and understand tactics, and I feel the easiest way to do that is with sharp opening play.

# Answer
> 4 votes
After reading a few of the answers on here, it does seem to me that the Colle is a little misunderstood. Despite the outward, superficial appearance of e3 being a quiet move, the Colle Zukertort or Zuke is actually a pretty attacking weapon. It doesn't perhaps involve the double edged attacks of say the Yugoslav Dragon with Bc4 or Traxler in the 2 Knights, kill or be killed but it is a principled opening. The centre tends to be fixed or semi fixed and this helps facilitate attacks on the wing and white is better equipped to attack the black kingside with ideas based around Ne5, f4, Rf3 - Rh3, Qh5, dxc5 - Bxf6, Bxh7, Nd2 - Nf3 - Ng5... black does not, certainly in the early-ish phase of the game have the same counter chances against white. If black can weather the storm then his chances on the queenside are quite promising but not overwhelming as white has a solid pawn structure and good piece coordination. White actually has chances earlier in the game, usually vs a Qc7 to play c4 and Rc1 also so it perhaps isn't as simple a system as people seem to think. I guess quite a few here are confusing the the Colle Zuke with the Colle K which is a more solid system in someways but again White can often generate strong chances on the kingside with a well timed e4 and the mainline has been resurged to an extent by the Phoenix attack. In my opinion the Colle is a good choice for players who have experimented with a few openings first, looked at some on the classics and want to settle on a sensible repertoire that will give them good chances of an attack at little risk. It must also be said that getting into the Colle itself help vary the play as you will also experience other positions to the standard "mainline" set up to help your chess development, also, you will need something else vs Kings Indian, Grunfeld, Dutch set ups as the Colle is ineffective vs those openings. I recommend Killer Chess Opening Repertoire by Summerscale and Starting out d pawn attacks by Richard Palliser. Hope that's of use to you.

# Answer
> 3 votes
"Aggressive" is a vague word that's usually meaningless when applied to an opening. It's quite possible to be either aggressive or passive in the Colle, or in pretty much any other opening. Aggression lies in how you play the opening, not the opening itself.

In the Colle, yes, you can bank everything on the attack on h7 (beginners with the system generally do) but if that's all you do, you'll miss out on a lot. The basic idea of the Colle, stripped of frills, is to break open the center to create free play for your pieces. Sometimes that results in the h7-assault, sometimes it's a central breakthrough, and sometimes it's simply trading down to a won endgame (this typically happens after swapping the white e- and d-pawns for the black c- and d- pawns -- the offside pawn majority this creates for white can quite often win all by itself). The point is you pay attention and take the course that best suits you.

The main strength of the Colle for beginners lies in the almost granite move order; white makes pretty much the same moves, builds pretty much the same tabiya, the same starting formation, no matter what Black does. That means a beginner has less to think about when the game starts, just bring out your pieces and then start looking for targets. But what makes it more useful for a beginner than a Stonewall, for example, is in how easily the beginner can use it to learn other types of positions. It's easy to start out in a Colle, and switch into a Queen's Gambit variation when it's advantageous to do so -- until you play c3, you're typically no more than two moves away from a queen's gambit at any point in the Colle. And, in fact, a lot of the "anti-colle" systems out there prove quite vulnerable to those transitions. When you see the defender starting to fortify against an attack you haven't committed to, it's quite profitable to pick other targets.

The Colle is only a one-trick pony if you play it that way. It's up to you. It does make an interesting "home ground" for players just learning how to handle middle game positions -- it's a place to stand while working on other ideas. For example, you start out playing for the rapid king-side attack. As you gain knowledge about those positions, which ones are favorable and which aren't, you add in playing for the isolated d-pawn positions (they usually come when Black trades d-pawn for white's e-pawn, then forces both c-pawns to capture on d4) learning which ones of those work well for you and which don't. Once those positions become familiar, try making the transition to the offside majority endgame positions and learn them.

# Answer
> 3 votes
I think the Colle-Zukertort is great as part of a white repertoire, but isn't appropriate against all black responses, especially stuff with ...g6 or a Queen's Indian setup with ...b6 and no ...d5.

I usually open with 1. d4 and 2. Nf3. If black responds with ...d5 on the first or second move, then I go for the Colle-Zukertort.

After 1. d4 Nf6 2. Nf3 g6, I go 3. c4 and play the KID or Gruenfeld (Makogonov h3 vs KID and e3/Qb3 vs Gruenfeld)

After 1. d4 Nf6 2. Nf3 e6 3. e3, I'll get either a Colle-Zukertort if black plays ...d5, or a classical QID if black plays ...b6.

Obviously, you need something against the dutch (1. d4 f5), and stuff like 1. d4 c5, 1. d4 e5, etc.

I prefer this method of mixing a few d4/c4 lines (versus KID, QID and Gruenfeld) with a system opening, to reduce the theoretical workload while still having enough variety of positions to keep improving as a player. You just have to choose your lines carefully to avoid getting move-ordered into an opening you don't want to play.

If you don't want to play c4 vs the KID and Gruenfeld, you could always try the Tarzan Attack (1. d4 Nf6 2. Nf3 g6 3. Nc3 d5 4. Bf4 Bg7 5. Qd2) where the idea is to castle queenside and go for a quick kingside attack with h4-h5.

# Answer
> 3 votes
Many people who disparage the Colle have never really studied it. It is solid and has a very clear objective that is easy to understand. The Colle is about accumulating small advantages and this may not fully be appreciated until move 30 or 35. Someone made a comment that learning to play the Colle won't teach you how to play chess, it will only teach you how to play the Colle. That is absolute absurdity. Get a good book on the Colle and take some time to really learn it. Make sure you understand WHY you are making the moves you are making and not just MEMORIZING the opening moves. You'll be glad you did.

# Answer
> 2 votes
The Colle Zukertort is a very simple opening, and can serve as a complete white opening repertoire. It was recommended by FIDE Trainer Jason Ciano, as well as many former top US players.

It teaches the white player how to activate the pieces in an ordered function, and, in some lines, achieve equality with a slight pawn center. It teaches good endgame skills and piece positioning.

Sharp positions like the Sicilian Dragon teach theoretical memorization, and it does not improve positional understanding. Nowadays, with computer analysis, sharp positions have theoretical improvements every few months, causing the player to constantly have to memorize new opening variations, leading to a dependency on memorization, not understanding.

# Answer
> 2 votes
I only play Colle system kind of openings (Classical Colle, Colle-Zukertort, Stonewall etc.,) I somehow am very comfortable with the structures it creates on the board. They are not aggressive at all, compared to the other stuff, which is why I have adopted it. On the contrary, the primary advice given to an improving chess player is NOT to stick to a particular class of opening, as though it "belongs" to you and you have some emotional attachment towards this.

# Answer
> 1 votes
It doesn't matter if you win fast or win slowly. A win is a win and the Colle will give you the wins you're looking for. You can tell because people are playing all sorts of anti-Colle lines just to avoid this "passive" opening. It's far from passive. White develops his pieces, giving black no targets and then at the precise moment, opens the game with the thematic e4 thrust.

# Answer
> 1 votes
We all start as beginners, as we all start on a small bicycle - not driving a car. The Colle or the London are good places to start and learn how and what along with some wins. As we grow and mature as chess players, then we can move on to more challenging or "sharp" openings. Ones that fit our chess personality. Some past grandmasters were attacking players, some were defensive. Whatever fits the persons chess personality.

There is no one be-all/end-all opening that promises a win. That comes down to the skill and experience of the player.

# Answer
> 0 votes
In addition, I believe that if you play the Colle passively you will simply let Black equalise, or better. The whole system is based on a kingside attack from solid foundations.

# Answer
> 0 votes
The Colle is about building very small advantages over a long period of time. In fact, you may not see the fruits of all your labors until move 30-35 in many cases. Bear in mind there are two methods for playing the Colle, the Koltanowski and Zukertort. The Koltanowski is a slow, precise system where White focuses on d4 and then frees his dark-squared bishop for the rest of the game. The Zukertort does have more of an attacking flair and will give White more excitement.

# Answer
> 0 votes
Colle-Zukertort is a good way to advance beyond beginner. The whole purpose of the opening is to teach you how to play "sound," chess, and to beat people who don't play that way.

Once you've advanced beyond beginner, you will want greater variety of openings and games. Colle-Zuckertort is a "slow" system, and once you've reached a certain level, you will want openings that give you a chance to win faster.

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Tags: opening, pawn-structure, colle-system, colle-zukertort
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# Question
Title: Is the Scandinavian Defense a good opening for beginners?
Is the Scandinavian Defense a good opening for beginners?

I'm wondering this because I'm a beginner and I mainly try to do this opening.

# Answer
The opening is playable at all levels, though quite rare in grandmaster play. Here is what chess.com says on the opening:

> Although the Scandinavian is not played much by grandmasters, it is generally considered to be an opening that is easy to learn and worth trying out for beginners and club level players.

I believe the appeal of the opening is that it is quite conceptual. After 3...Qa5, the mainline, none of the pieces are attacking each other, meaning that there aren't many tactics or much theory in the early part of the game.

```
[FEN ""]

1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4.d4 c6 {Creating a bolt hole for the queen if she is attacked.} 5.Nf3 Nf6 6.Bc4 Bf5 {Developing the bishop before locking it outside of the pawn chain.} 7.Bd2 e6 {Black will develop the dark square bishop, castle kingside, then play for central pawn breaks.}

```

Both sides have developed simply and logically.

**Edit:** Others have stated the Scandinavian is not testing at the high level. If you wish to employ different openings later on, the and have good reputations and similar pawn structures to the Scandinavian.
> 7 votes

# Answer
In my opinion you should try other openings as well.

The Scandinavian itself is sound, but it actually doesn't teach you many "basic opening principles". It breaks some of them, instead (like "avoid moving your pieces twice" and "develop your light pieces before your heavy pieces").

Since there's a strategy beyond the opening despite all these "side effects", it's good anyway. But in the long term you could end up with very bad habits if you continue playing it without critical reasoning.

So, as a conclusion, I would not recommend the Scandinavian if you are a beginner. I think that other openings are better, at your level (like the Philidor defence, the 2 Knights or the Ruy Lopez), even if the theory behind is much more difficult to study: but you shouldn't memorize all the lines... instead, you should try to understand the principles behind the first moves of each of these openings.
> 4 votes

# Answer
Just as a preference, 1 e4 d5 2. exd5 Nf6 is a different (modern treatment?) method to play, allowing you to capture on d5 with a piece, avoiding the tempo play by white after 2. ... Qxd5 3. Nc3, etc. Either way, there is little risk.

Some points about the Scandinavian Defense:

Positionally Quiet; One of the simplest openings for Black; There is only one type of pawn structure in the centre characterized by a 1/2-open file for both sides.; All of Black's pieces have good squares to develop to.; Black's pawn structure (after e6 and c6) has no weaknesses; Offers White no direct attack against the Black king; White has a space advantage; Black is slightly passive;

The Portuguese Gambit (1. e4 d5 2. exd5 Nf6 3. d4 Bg4) was recently featured in New In Chess Yearbook #117.

Unless you are a top flight player, it is completely reasonable to include it in your repertoire.
> 3 votes

# Answer
I don't think there is anything wrong with the Scandinavian itself. The reason why it's not often played at top level is that there are "improved versions" in the Rubinstein French and Caro-Kann Defence, which will leave you with the same pawn structure but all those queen moves in the opening are not needed
> 2 votes

# Answer
The Scandinavian is one of the easiest openings where Black can neutralize the ultra sharp openings of e4 against White . If the White Player is very aggressive , like sharp tactical lines and offers gambits then Scandinavian is one of the best weapon to encounter against those players .

It is even played at higher levels . The lines are even easier to learn and Black achieves a decent Game . From a Strategic Perspective the Scandinavian is less prone to Sacrifices unlike Sicilian defence which has theoretical sacrifices example in Najdorf Poison pawn and with moderate play it extends up to the End game most often where Win is decided by the silly mistake of the opponent .
> 0 votes

# Answer
The Scandinavian is easy to learn and easy to play. Recovering the pawn with the Queen in the opening isn't bad because even though White chases the Queen with Nc3, the Knight doesn't belong on c3. White has to move that Knight a second time in order to play c4 to help crack open the position. So White loses a tempo just like Black does. It is played at the top levels sometimes. I just played through a game where Black was over 2700 and played it with a resulting draw. Bent Larsen beat Karpov with it and Annand almost beat Kasparov with it. Magnus played it using the Qd8 variation and won with it.
> 0 votes

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Tags: opening, beginner, scandinavian-defense
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title: Definition of Soundness

text:
# Question
Title: Definition of Soundness
What exactly does it mean for a gambit to be unsound? I see this term being used a lot but I have yet to come across a precise definition.

Is it enough for white to lose the advantage that comes with being the first player? What if black is better with best play but not winning?

How is soundness defined if black is the one playing the gambit?

# Answer
Adapted from here.

A gambit is said to be '**sound**' if it is capable of resulting in an advantage against the opponent. **There are three general criteria in which a gambit is often said to be sound:**

1. **Time gain:** the player accepting the gambit must take time to obtain the sacrificed material and possibly must use more time to reorganize his pieces after the material is taken.
2. **Generation of differential activity:** often a player accepting a gambit will decentralize his pieces or pawns and his poorly placed pieces will allow the gambiteer to place his own pieces and pawns on squares that might otherwise have been inaccessible. In addition, bishops and rooks can become more active simply because the loss of pawns often gives rise to open files and diagonals.
3. **Generation of positional weaknesses:** finally, accepting a gambit may lead to a compromised pawn structure, holes or other positional weaknesses.

An example of a **sound** gambit is the Scotch Gambit:

```
[FEN ""]
1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Bc4.

```

Here Black can force White to sacrifice a pawn speculatively with 4...Bb4+, but White gets very good compensation for one pawn after 5.c3 dxc3 6.bxc3, or for two pawns after 6.0-0 inviting 6...cxb2 7.Bxb2, due to the development advantage and attacking chances against the black king. As a result, Black is often advised not to try to hold on to the extra pawn.

An example of an **unsound** gambit is the so-called Halloween Gambit:

```
[fen ""]
1.e4 e5 2.Nf3 Nc6 3.Nc3 Nf6 4.Nxe5?! Nxe5 5.d4.

```

Here the investment (a knight for just one pawn) is too large for the moderate advantage of having a strong center.
> 6 votes

# Answer
I would add to vs97's answer that not all sound openings lead to an advantage. Indeed, when playing Black, we are often happy with an equal game, thus defences that lead us there are "sound".

Some openings that don't give anything special for White are still considered "sound" (I don't think anyone would say the London System is unsound). So I would say that for an opening to be unsound, it must have a clear refutation
> 1 votes

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Tags: opening, gambits, terminology
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# Question
Title: Anti-cheating: should there be a limit to a number of toilet breaks per game per player?
With the advent of smart phones, cheating in chess tournaments has become rife to the extent that if unguarded it will kill the spirit of competitiveness. There has been several such cases, accussations and allegations including the infamous Vladimir Kramnik and Veselin Topalov toiletgate. In some cases a player can make *perpetual* toilet visits; move-after-move which might seem suspicious. This is partly due to unlimited *"freedom of movement"* during the game.

For instance in other sports like soccer - *even though there's no computer cheating* \- halftime breaks are timed and controlled. Should chess adopt a limit to a number of toilet breaks per game per player, say in a standard game, a player can only go to the bathroom after making a certain number of moves 10, 20, 40?

What would be the advantages or setbacks to this limited breaks?

# Answer
> 48 votes
No, there shouldn't and if you live to be 80 you will probably understand why.

A few years ago in a tournament where I was one of the arbiters a 16 year old boy was playing an old guy in his 80's in round 2, both of them were rated about 1950. There had recently been the case of the Bulgarian phone cheat who had consulted a phone hidden behind one of the toilets.

The 16 year old came up to me and said "Can I have a word with you outside?" It sounded very serious so I agreed. He then explained that his opponent was getting up regularly to go to the toilet even once doing it when it was his turn to move. The boy was worried his opponent was a phone cheat.

Had I been the boy's coach and not the arbiter I would have been able to explain the reasons. The old guy had just recently come out of hospital where he had had prostate surgery. The truth was he should really have been at home recovering with his feet up not playing chess but who is going to tell an 80 year-old how to live his life? In the previous round he had blundered his queen against a player rated about 1750. I would have told the boy to just keep playing good moves and the old guy was sure to blunder sooner or later. That is what happened in the game, by the way.

Of course as the arbiter I couldn't give him helpful information like that. Instead I told him I would check the toilets for mobile phones and keep an eye on the old guy for the rest of the round, which I did.

Note that the toilets are generally in the bounds of the playing venue but not in the playing area so going to the toilet when it is your turn is not allowed unless you get the permission of the arbiter. If you have a medical condition which makes this likely then you can speak to the arbiter before play to explain to the arbiter and get this permission.

If you are a woman then you can't have prostate problems but if you have children you may experience similar problems with needing to make regular visits to the toilet for some time after giving birth.

In short imposing limits on toilet breaks would be inhumane.

# Answer
> -2 votes
I fully agree with Brian Towers' answer, but want to point out an **alternative to having a limit: ask for an upfront estimate**. Before the game starts, ask each participant to estimate how many toilet breaks he/she estimates will be needed. This number is communicated to the opponent1.

People that needs to go often will have no problems in justify a higher number, while people that go to the bathroom to cheat will not. Some of the cheaters might not have planned to cheat beforehand, but will just take the opportunity when feeling the need to during the game, and having given an estimate beforehand will create some accountability that most likely will deter some cheating.

---

1 Probably after the game is over. Otherwise it might result in *"oh, my opponent has double my number, well then I can throw in a couple extra visits"* thinking.

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Tags: tournament, cheating
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# Question
Title: Why is it important to study classical games?
Many masters have always recommended the study of classical games. Why is it important to study them and what is so special about classical games?

# Answer
> 11 votes
There are a variety of reasons:

* Regardless of when they were played, there is always a lot to learn in analyzing better players's games.
* Players from a century ago often used simpler strategical themes that are easier to understand and apply.
* Opening theory was not that well developed back then, so the "actual game" starts earlier on. You also wouldn't find any "weird" moves that are justified by some obscure tactical sequence that only a computer can see.
* Games between masters were, unlike today, rarely decided by at-home preparation.
* Old masters had an awesome endgame technique.
* The opposition was often weaker than today, so masters could execute their plan in a "pure" form. In more modern games, the main plan is most of the time hidden behind counterplay, counters to that counterplay, and so on...
* A final point would be that these games have been reviewed multiple times by a lot of different people, each of them making their contribution

# Answer
> 5 votes
I suppose that this question is in the context of a motivated beginner who wants to significantly improve his / her chess. I think it's because they are of recognized value, and so they are like classical computer science challenges, classical math problems, and so on. No one can call himself an expert in that field and ignore them. It's the same with chess. Of course there are many modern games that have the same instructional value, if not more, of the well-known classical games. And we should also consider that competitive chess has changed a lot in recent years, especially at top levels.

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Tags: training, study
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# Question
Title: Is there a rule for anti noise earpieces?
Few days ago, one of my opponent wore Bose anti noise earpieces. Of course, I didn't call the referee cause I knew that it wasn't a cheat technique. But I was wondering what is the rules for that kind of object. I think that some players could confuse with earphones and call referee for cheat attempt. Thank you for your answers :)

# Answer
> But I was wondering what is the rules for that kind of object.

Strictly speaking they are not allowed without the arbiter's permission.

This is what the latest FIDE Laws of Chess state:

> 11.3.2.1 During a game, a player is forbidden to have any electronic device not specifically approved by the arbiter in the playing venue.
>
> However, the regulations of an event may allow such devices to be stored in a player’s bag, provided the device is completely switched off. This bag must be placed as agreed with the arbiter. Both players are forbidden to use this bag without permission of the arbiter.
>
> 11.3.2.2 If it is evident that a player has such a device on their person in the playing venue, the player shall lose the game. The opponent shall win. The regulations of an event may specify a different, less severe, penalty.
> 3 votes

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Tags: rules
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# Question
Title: Why did I lose on time with three pawns versus a knight? Shouldn't it be a draw?
I just lost an online game on time (while playing on lichess.org). I had three pawns and my opponent had just a knight. I don't understand why it's not a draw. Shouldn't it be a draw because my opponent does not have enough material to checkmate me?

# Answer
> 31 votes
Draw with insufficient material is covered in article 9.6:

> The game is drawn when a position is reached from which a checkmate cannot occur by any possible series of legal moves, even with the most unskilled play.

With a given material, it is possible to construct a checkmate (assuming your cooperation or horrible blunders), so it is not a draw.

# Answer
> 29 votes
Worst-case scenario:

* Upgraded all your pawns to knights
* Your king is at `Ka8`
* Your knights surround your king, so at `Nb8`, `Na7` and `Nb7`
* Opposition knight is at `Nc7#` \- *checkmate*!

So it is indeed possible to lose, thus not a draw.

# Answer
> 9 votes
From FIDE Laws of Chess (2018 version):

> 6.9 Except where one of Articles 5.1.1, 5.1.2, 5.2.1, 5.2.2, 5.2.3 applies, if a player does not complete the prescribed number of moves in the allotted time, the game is lost by that player. However, the game is drawn if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves.

(The articles in chapter 5 all concern checkmate, stalemate, resignation or agreement to draw. I.e. any conventional consideration other than time that causes the game to be over.)

So your time ran out, and your opponent can checkmate you through some legal series of moves, which means you lost.

I do not know that Lichess folows the FIDE laws, but it seems like a reasonable assumption in this case.

# Answer
> 6 votes
As others mentioned, you cannot get the draw because you can still get checkmated.

In fact I have actually seen this kind of position get lost in practice, as follows:

You are on Ka8 and have just played a7 pawn (knight, rook or even bishop have very similar effect and could be obtained via promotion), opponents king is on Kc8 or Kc7 and opponent plays Nb6#

# Answer
> 6 votes
From the lichess.org FAQ:

> In the event of one player running out of time, that player will usually lose the game. However, the game is drawn if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves (FIDE handbook §6.9).
>
> Note that it can be possible to mate with a single knight or bishop if the opponent has pieces that could block the king.

I assume that the statement in the second paragraph is being used as the basis for ruling this as a timeout rather than a draw (and, as others have pointed out, this would be a correct call in this case.)

Perhaps it is worth noting that, in general, it is computationally infeasible to determine when a player cannot win, and furthermore, an automated system cannot yet be expected to identify all such cases that are obvious to an experienced player, so it must be expected that lichess will use tractable rules such as those quoted.

# Answer
> 4 votes
By USCF rules, you wouldn't have.King + Bishop and King + Knight are defined to be insufficient mating material unless that side can demonstrate a forced win (all forced wins are very short, so this isn't hard to do if it exists).

> 14E: Insufficient material to win on time:
> The game is drawn even when a player exceeds the time limit if one of the following conditions exists:
> 14E1: Lone king
> 14E2: King and bishop or king and knight

The presumed rationale behind this is that avoiding checkmate from that material combination is so trivially easy that a win on time is the only realistic way to win.

---
Tags: rules, online-chess, draw
---


# Question
Title: Bughouse chess tournament pairing software?
Does anyone know of a (free) program which could be used to organize a bughouse chess tournament?

Where in each round the partner you have would change. (With the basic idea to put a good and 'less good' player in the same team.) The good player would be defined as the one with the most bughouse team wins.

Or how should I try to manage such a tournament? Any ideas?

# Answer
There is no pairing program which can do what you want. No program exists to change the partners every round according to the previous results. Pairing programs also try and avoid pairing players or teams which have played before.

Exactly how the partners would vary and how you would decide who had played whom is not clearly defined in your system. Your idea needs more work.
> 2 votes

# Answer
Bughouse is not the only partnered game where this would be a problem worth solving.

Here is a description of what you want for Euchre tournaments; in this case they call it a "progressive" tournament format (not sure why). It still involves manually tracking results (no software) though. If you really must have software you might have to do some more googling.

Just remember that if it works for something like euchre, it will work for bughouse also.
> 1 votes

---
Tags: software, bughouse
---


# Question
Title: How to detect invalid pawn structures (not based on opponent material) for FEN valdation?
I'm going to further expand a FEN validation function I have been working on for some time to include illegal pawn formations such that:

> ... for example white pawns could never be on a2, a3, and b2; there is no way a pawn could be on both a3 and b2. (source)

This particular test doesn't require to take opponent missing material into consideration (it could, but I have that on a separate test to check every column with multiple pawns and determine the minimum missing material the opponent should have, but that test is different, I only want to focus on this other test assuming infinite material can be used to reach those positions).

So far, my approach has been to draw a triangle from any pawn (excluding the ones that sit on the starting rank, which wouldn't allow a triangle to be drawn) all the way to the starting rank, then counting all the pawns that would fit on the base line of the triangle (starting rank). In the case the triangle goes out of bounds, those pawns are not counted:

That amount of pawns on the bottom of the triangle are the upper exclusive limit that pawns could then appear anywhere inside the triangle (because the test is applied to each pawn and each one will draw their own triangles and because the test is a generalized "no invalid pawn structures?", as in, all or nothing, it is safe to give big triangles with cluttered pawns a pass, since later on, the pawns inside will undergo the same test).

Example from the left image with limit of 3, there should be 0-2 to be a legal pawn structure.

Will this solution always work or there are times where this limit will be incorrectly generated? Can this be simplified further using a different reasoning or methods?

Any ideas, feedback, alternative solutions are appreciated.

# Answer
There is at least one case where your method will fail: pawns on f2, g3, h2 and h3.

The structure is illegal, but drawing triangles from every pawn will not show this. To catch this, you'd have to draw the triangle from every square of the chessboard (h4 in this case demonstrates the illegality).

So as you said, draw triangles, but instead of starting from pawns, draw them from every square on the board. (For white, it actually suffices to try every square from the 3rd to the 8th rank.)
> 3 votes

---
Tags: pawn-structure, illegal-move, fen
---


title: Is it possible to block a double check?

text:
# Question
Title: Is it possible to block a double check?
Is it possible to block a double-check, or is your only option to move the king? (I'm trying to code a chess game, to then go on to code a chess AI, and this would really help me)

# Answer
> 3 votes
Moving the king is the only way to escape a double check. There is no possible other move that will block both checks.

---
Tags: check, double-check
---


# Question
Title: Can it be useful for a player block with a hanging piece in a back rank mate situation?
Could the following situation possibly exist?

It's White to play, and Black is about to get back rank mated. This is because the King's mobility is restricted to a single file. Then White gives a check.

At this point, Black plays the best move that blocks with a hanging piece, where the blocking piece has no defense. White takes the piece with check, and black can now escape somehow.

An example of this is that by blocking check with a hanging knight, Black opens up a bishop's path to further block, but this time safely and checkmate is avoided.

# Answer
One more scenario that has not been mentioned yet is that an unprotected interposing piece might unblock a sliding piece leading to a discovered check, which prevents the capture of the interposed piece, like in the example below:

```
[FEN "3r2k1/6pp/4R3/8/2R5/1B6/5PPP/r5K1 w - - 0 1"]

1. Rc1 Rxc1+ 2. Re1+

```
> 4 votes

# Answer
```
[FEN "R5k1/5ppp/8/2r5/1b6/8/5PPP/6K1 b - - 0 1"]

1... Rc8 2. Rxc8+ Bf8

```

This is an example of what Tim Krabbé calls an 'unguarded guard' \- a linepiece checks, and a piece interposes on an unguarded square. That page mentions Topalov - Polgar, Novgorod 1996 (see below); while not a true back rank mate, it comes close. Here are some endgame studies with other types of Unguarded Guards.

```
[FEN ""]
[Event "Novgorod"]
[Date "1996-07-27"]
[White "Veselin Topalov"]
[Black "Judit Polgar"]
[StartPly "92"]

1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6 5.Nc3 Qc7 6.Be3 a6 7.Bd3
b5 8.Nxc6 Qxc6 9.O-O Bb7 10.a3 Nf6 11.Re1 Be7 12.Qf3 d6 13.Qh3
h5 14.Bg5 Qc5 15.Be3 Qc6 16.f3 g5 17.a4 b4 18.Na2 g4 19.fxg4
d5 20.c3 bxc3 21.bxc3 Nxg4 22.Bd4 Bc5 23.Be2 Nf6 24.e5 Ne4
25.Nb4 Bxd4+ 26.cxd4 Qb6 27.Nc2 Rc8 28.Rab1 Qa7 29.Bd3 Rg8
30.a5 Bc6 31.Rb6 Bb5 32.Bxe4 dxe4 33.Rxe6+ Kf8 34.Qa3+ Kg7
35.Re7 Rc7 36.Rxc7 Qxc7 37.Ne3 Kh8 38.Rc1 Qd8 39.d5 Qg5 40.Qc3
Kh7 41.Qd4 Bd3 42.d6 h4 43.Rc7 Rb8 44.Rxf7+ Kg8 45.e6 Qxe3+
46.Qxe3 Rb1+ 47.Qc1 Rxc1+ 48.Kf2 Rc6 49.Rd7 Bb5 50.Ke3 Rc2
51.Rc7 Re2+ 52.Kf4 Rf2+ 53.Kxe4 Re2+ 54.Kf5 Rf2+ 55.Ke5 Re2+
56.Kf6 Rf2+ 57.Ke7 Re2 58.d7 Bxd7 59.Kxd7 Rd2+ 60.Ke8 1-0

```
> 17 votes

# Answer
A different, but similar, situation would be with a castled king, minus the rook, behind two pawns with a knight inbetween them.

```
[FEN "r3k3/8/8/8/8/8/5PNP/6K1 b - - 0 1"]

1... Ra1+ 2. Ne1 Rxe1+ 3. Kg2

```
> 10 votes

---
Tags: tactics, checkmate
---


# Question
Title: Is it true that at any time only one piece can put king in check?
I am writing a simple chess game in which I have to determine the end game conditions. My algorithm requires the piece that is putting the opponent king in check, and checks the following:

* King cannot escape
* Piece cannot be eliminated
* Path cannot be blocked

If all three conditions satisfy, then it is checkmate. However, I am wondering if there can be more than one piece simultaneously putting a king in check. It doesn't seem to be possible, but I can't come up with a proof for it. For example, is it possible for 2 rooks to put a king in check at the same time? Personally, I don't think that it's possible.

# Answer
> 22 votes
Double check is a fine tactic. An example would be a bishop lined up on the same diagonal as the king with a rook or knight in the way blocking the check. The rook or knight moves giving check to the king and also uncovering the check from the bishop. The king must move since there is no way to block two different lines or take two different pieces at the same time.

# Answer
> 10 votes
If you include a pawn that has just been promoted to a rook, then yes, it is quite possible to give check with two rooks simultaneously.
Consider the position where White has Ke1 Re6 e7 g7, and Black has Ke8 Nf8. White moves 1. exf8(R)++ and gives check with the newly promoted rook as well as the existing rook.
Checkmate could also be given in this way if, for example, White had a queen on g7 instead of a pawn.

# Answer
> 7 votes
For the purposes of writing an algorithm, I don't think I would approach it that way at all.

On any given ply, you generate a list of legal moves to investigate. A move is illegal if, in the resulting position, your king is in check. If there are no legal moves, and the king is currently in check, then it's checkmate.

You don't need an algorithm to figure out whether a check can be blocked or whether the checking piece can be eliminated, or any other scenarios. The lack of any legal moves in the position indicates that already.

# Answer
> 5 votes
Double check is possible.

One piece must move to deliver a check, while simultaneously allowing another piece to give check that had been blocked by the moving piece.

Examples:

* a rook could move on the rank to check on a file while uncovering a bishop check
* a knight could move to give check while uncovering a rook check or a bishop check

# Answer
> 5 votes
If you consider Chinese chess (Xiang Qi), then technically even triple check is possible. Imgaine the enemy king, your knight or bishop, your rook and your cannon all in line in that order. Then if the knight or bishop can move away to give check it is a triple check. Another difference is that a double check by rook and cannon on the same line could be blocked in one move, so even though technically it is a triple check, because the cannon can leap over the rook, it seems more similar to a double check with respect to blocking.

# Answer
> 2 votes
The King can be checked by multiple pieces via a double check tactic. Consider the following position:

White Queen on g4, White Rook on f5, Black King on d7.

White plays 1. Rf7+, and Black's King is checked by both White's Rook and Queen.

For your algorithm, it would be checkmate if BOTH pieces cannot be blocked, taken, avoided, etc. Consider the following:

1. e4 e6 2. Nc3 d5 3. exd5 exd5 4.d3 d4 5. Ne4 Nc6 6. Qe2 Bg4 7. Nf6#

The final position is a double check and checkmate. Notice how both White's Queen and Knight can be taken or avoided, if you consider them individually. However, they cannot BOTH be taken/avoided/blocked, so Black is checkmated.

# Answer
> -6 votes
In standard chess, you can illegally can check a king 8 times at once. Consider 8 knights a that are leap away from the enemy king.

```
[FEN "4k3/8/3n1n2/2n3n1/4K3/2n3n1/3n1n2/8 w - - 0 1"]

```

The king still has his orthogonal moves left, and is now 1 move away from attacking 2 of the knights. Since both of them are unprotected, one of the 8 knights may move to where the king was, to protect all 7 other knights. The King is not necessarily trapped, but certainly not free.

---
Tags: rules, checkmate, check
---


# Question
Title: In a KP-K endgame, if the enemy king is in front of the pawn, is it always a draw?
In a KP-K endgame, if the enemy king is in front of the pawn, is it always a draw?

I've tried it in various positions, yet my opponent always is able to get in front somehow and promote the pawn.

I hear it's always always a draw. I've been playing for so many years, and never figured out how to get the draw. What is the correct technique to do this that always works?

# Answer
> 10 votes
If the king is on the sixth and the pawn is on the fifth (and it's not a rook pawn), then it's a win for the side with the pawn, no matter who has the move:

```
[FEN "4k3/8/4K3/4P3/8/8/8/8 w - - 0 1"]

1. Kd6 Kd8 2. e6 Ke8 3. e7 Kf7 4. Kd7 Kf6 5. e8=Q *

```

With Black to move:

```
[FEN "4k3/8/4K3/4P3/8/8/8/8 b - - 0 1"]

1... Kd8 2. Kf7 Kd7 3. e6+ Kd8 4. e7+ Kd7 5. e8=Q+ *

```

If you back it up, though, the position is a win with Black to move and a draw with White to move. If White has to move first, Black can simply mirror the movements of the White king until White moves the pawn forward.

```
[FEN "8/3k4/8/3K4/3P4/8/8/8 w - - 0 1"]

```

If the pawn is in front of the king, the general strategy is to make sure to oppose the enemy king when it goes alongside its pawn, to prevent it from getting in front.

```
[FEN "4k3/8/4P3/4K3/8/8/8/8 w - - 0 1"]

1. Kd6 Kd8 2. Ke5 Ke7 3. Kf5 Ke8 (3... Kf8?? {This loses! If you take this critical square too soon, before the enemy king is alongside the pawn, you can't stay on the square when the enemy king does advance.} 4. Kf6 Ke8 5. e7 Kd7 6. Kf7) 4. Kf6 Kf8 5. e7+ Ke8 6. Ke6 {Stalemate.} 1/2-1/2

```

---
Tags: endgame, strategy, pawn-endgame
---


# Question
Title: Is it valid according the FIDE chess rule?
From FIDE Law of Chess, article 3.8, it is stated as:

Now, coming to My game vs killin\_pieces on lichess.org :

After move 9, situation was something like this: b1 was threatened by my opponent's light square bishop:

Still I was able to give him a discovered check on move no. 10.

which clearly contradicts FIDE Law of chess article 3.8.2.a, stated as :

> Castling is prevented temporarily: if the square on which the king stands, or **the square which it must cross**, or the square which it is to occupy, is attacked by one or more of the opponent's pieces

Can anyone please explain me how can this be possible ?

# Answer
> 10 votes
The king does not cross b1 (only the rook does). It also does not end up standing on b1 following the castling. Hence, the quoted rule is not violated.

---
Tags: online-chess, castling, online-blitz, lichess
---


title: Chess program for Linux/Unix console

text:
# Question
Title: Chess program for Linux/Unix console
For reasons I'd rather not get into, what chess programs work well on the console (ie. does not require X Windows)? Something with an ASCII visualization of the board would be incredibly helpful (I'm still a chess newbie).

# Answer
After installing GNU Chess run the command gnuchess from the terminal, it would look something like this:

```
~$ gnuchess
GNU Chess 5.07
Adjusting HashSize to 1024 slots
Transposition table:  Entries=1K Size=48K
Pawn hash table: Entries=0K Size=32K
White (1) : e4
1. e4

black  KQkq  e3
r n b q k b n r
p p p p p p p p
. . . . . . . .
. . . . . . . .
. . . . P . . .
. . . . . . . .
P P P P . P P P
R N B Q K B N R

Thinking...
Looking for opening book in book.dat...
Looking for opening book in /usr/share/games/gnuchess/book.dat...
Read opening book (/usr/share/games/gnuchess/book.dat)...
Loading book from /usr/share/games/gnuchess/book.dat.
40304 hash collisions...  Opening database: 265053 book positions.
In this position, there are 11 book moves:
 Nc6(71/77/22/32)  Nf6(54/113/88/113)  a6(75/3/1/0)  b6(67/11/3/9)
 c6(52/451/376/743)  d6(52/178/153/229)  e6(52/651/582/970)        g6(59/155/88/117)
 c5(56/2535/1691/2912)  d5(54/47/38/35)  e5(54/2518/1938/3369)

 c5(1322)  e5(1312)  e6(376)  c6(277)  d6(141)  g6(136)  Nf6(109)  Nc6(108)
 a6(76)  d5(76)  b6(70)

white  KQkq  c6
r n b q k b n r
p p . p p p p p
. . . . . . . .
. . p . . . . .
. . . . P . . .
. . . . . . . .
P P P P . P P P
R N B Q K B N R

My move is : c5
White (2) :

```
> 15 votes

# Answer
What about GNU Chess? It has a plain terminal interface but supports visual interfaces such as XBoard.
> 9 votes

# Answer
Sunfish has a simple terminal interface, if you just want to play a bit for fun:

```
$ git clone https://github.com/thomasahle/sunfish.git
...
$ python sunfish/sunfish.py

  8 ♖ ♘ ♗ ♕ ♔ ♗ ♘ ♖
  7 ♙ ♙ ♙ ♙ ♙ ♙ ♙ ♙
  6 . . . . . . . .
  5 . . . . . . . .
  4 . . . . . . . .
  3 . . . . . . . .
  2 ♟ ♟ ♟ ♟ ♟ ♟ ♟ ♟
  1 ♜ ♞ ♝ ♛ ♚ ♝ ♞ ♜
    a b c d e f g h

Your move: e2e4

  8 ♖ ♘ ♗ ♕ ♔ ♗ ♘ ♖
  7 ♙ ♙ ♙ ♙ ♙ ♙ ♙ ♙
  6 . . . . . . . .
  5 . . . . . . . .
  4 . . . . ♟ . . .
  3 . . . . . . . .
  2 ♟ ♟ ♟ ♟ . ♟ ♟ ♟
  1 ♜ ♞ ♝ ♛ ♚ ♝ ♞ ♜
    a b c d e f g h

My move: g8f6

  8 ♖ ♘ ♗ ♕ ♔ ♗ . ♖
  7 ♙ ♙ ♙ ♙ ♙ ♙ ♙ ♙
  6 . . . . . ♘ . .
  5 . . . . . . . .
  4 . . . . ♟ . . .
  3 . . . . . . . .
  2 ♟ ♟ ♟ ♟ . ♟ ♟ ♟
  1 ♜ ♞ ♝ ♛ ♚ ♝ ♞ ♜
    a b c d e f g h

Your move:

```
> 6 votes

# Answer
chs

> Play chess against the Stockfish engine in your terminal.
> 5 votes

# Answer
Follow my commands. Play Stockfish on the terminal.

```
wget https://stockfish.s3.amazonaws.com/stockfish-6-linux.zip
unzip stockfish-6-linux.zip
cd stockfish-6-linux/Linux
./stockfish_6_x64

Stockfish 6 64 by Tord Romstad, Marco Costalba and Joona Kiiski
d

 +---+---+---+---+---+---+---+---+
 | r | n | b | q | k | b | n | r |
 +---+---+---+---+---+---+---+---+
 | p | p | p | p | p | p | p | p |
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 |   |   |   |   |   |   |   |   |
 +---+---+---+---+---+---+---+---+
 | P | P | P | P | P | P | P | P |
 +---+---+---+---+---+---+---+---+
 | R | N | B | Q | K | B | N | R |
 +---+---+---+---+---+---+---+---+

Fen: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
Key: B4D30CD15A43432D
Checkers:
e2e4
Unknown command: e2e4
go movetime 1000
info depth 1 seldepth 1 multipv 1 score cp 84 nodes 21 nps 90 tbhits 0 time 232 pv e2e4
info depth 2 seldepth 2 multipv 1 score cp 82 nodes 62 nps 266 tbhits 0 time 233 pv e2e4 b7b6
info depth 3 seldepth 3 multipv 1 score cp 75 nodes 162 nps 695 tbhits 0 time 233 pv b1c3 d7d6 e2e3
info depth 4 seldepth 4 multipv 1 score cp 60 nodes 417 nps 1789 tbhits 0 time 233 pv g1f3 e7e6 e2e3 d7d6
info depth 5 seldepth 5 multipv 1 score cp 136 nodes 1546 nps 6578 tbhits 0 time 235 pv g1f3 c7c5 e2e4 d7d6 d2d4
info depth 6 seldepth 6 multipv 1 score cp 21 nodes 4562 nps 19087 tbhits 0 time 239 pv g1f3 g8f6 d2d4 d7d5 b1c3 e7e6
info depth 7 seldepth 7 multipv 1 score cp 51 nodes 5949 nps 24787 tbhits 0 time 240 pv g1f3 g8f6 d2d4 d7d5 b1c3 e7e6 e2e3
info depth 8 seldepth 8 multipv 1 score cp 39 nodes 9124 nps 37547 tbhits 0 time 243 pv g1f3 e7e6 b1c3 d7d5 d2d4 g8f6 e2e3 a7a6
info depth 9 seldepth 9 multipv 1 score cp 39 nodes 13735 nps 55607 tbhits 0 time 247 pv g1f3 d7d5 d2d4 b8c6 b1c3 g8f6 c1f4 e7e6 e2e3
info depth 10 seldepth 13 multipv 1 score cp 28 nodes 25801 nps 101180 tbhits 0 time 255 pv g1f3 d7d5 d2d4 b8c6 b1c3 g8f6 e2e3 a8b8 h2h3 e7e6
info depth 11 seldepth 13 multipv 1 score cp 26 nodes 56118 nps 206316 tbhits 0 time 272 pv e2e4 d7d5 e4d5 g8f6 b1c3 f6d5 g1f3 e7e6 a2a3 b8c6 d2d4 h7h6
info depth 12 seldepth 16 multipv 1 score cp 25 nodes 194110 nps 549886 tbhits 0 time 353 pv e2e4 e7e5 b1c3 g8f6 g1f3 b8c6 f1b5 f8b4 e1g1 b4c3 d2c3 e8g8 d1e2 d7d5
info depth 13 seldepth 19 multipv 1 score cp 28 nodes 336964 nps 764090 tbhits 0 time 441 pv e2e4 e7e5 b1c3 g8f6 g1f3 b8c6 f1b5 f8b4 e1g1 e8g8 c3d5 f6d5 e4d5
info depth 14 seldepth 19 multipv 1 score cp 31 nodes 457658 nps 886934 tbhits 0 time 516 pv g1f3 g8f6 b1c3 d7d5 e2e3 e7e6 d2d4 b8c6 f1d3 f8d6 e1g1 e8g8 c1d2 e6e5 a2a3
info depth 15 seldepth 19 multipv 1 score cp 29 nodes 638239 nps 1022818 tbhits 0 time 624 pv g1f3 g8f6 b1c3 d7d5 d2d4 e7e6 e2e3 b8c6 f1e2 f6e4 e1g1 f8b4 c3e4 d5e4 f3e5 e8g8
info nodes 1246584 time 1003
bestmove g1f3 ponder g8f6

```
> 4 votes

---
Tags: software
---


# Question
Title: The Game of the Century - why didn't Byrne take the rook after he forked Fischer?
I'm guessing that there's a pretty simple explanation for this, but I can't seem to see it.

```
[White "Donald Byrne"]
[Black "Robert James Fischer"]

[fen ""]

1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. d4 O-O 5. Bf4 d5 6. Qb3 dxc4 7. Qxc4 c6 8. e4 Nbd7 9. Rd1 Nb6 10. Qc5 Bg4 11. Bg5 {11. Be2 followed by 12 O-O would have been more prudent. The bishop move played allows a sudden crescendo of tactical points to be uncovered by Fischer. — Wade} Na4! {!} 12. Qa3 {On 12. Nxa4 Nxe4 and White faces considerable difficulties.} Nxc3 {At first glance, one might think that this move only helps White create a stronger pawn center; however, Fischer’s plan is quite the opposite. By eliminating the Knight on c3, it becomes possible to sacrifice the exchange via Nxe4 and smash White’s center, while the King remains trapped in the center.} 13. bxc3 Nxe4 {The natural continuation of Black’s plan.} 14. Bxe7 {Forking Black's Queen and Rook - Brandon_J} Qb6 15. Bc4 (15. Bxf8 Rxf8 16. Bd3 (16.Be2)(16.Bc4)) Nxc3 16. Bc5 Rfe8+ 17. Kf1 Be6!! {If this is the game of the century, then 17…Be6!! must be the counter of the century. Fischer offers his queen in exchange for a fierce attack with his minor pieces. Declining this offer is not so easy: 18. Bxe6 leads to a ‘Philidor Mate’ (smothered mate) with …Qb5+ 19. Kg1 Ne2+ 20. Kf1 Ng3+ 21. Kg1 Qf1+ 22. Rxf1 Ne2#. Other ways to decline the queen also run into trouble: e.g., 18. Qxc3 Qxc5} 18. Bxb6 Bxc4+ 19. Kg1 Ne2+ 20. Kf1 Nxd4+ {This tactical scenario, where a king is repeatedly revealed to checks, is sometimes called a “windmill.”} 21. Kg1 Ne2+ 22. Kf1 Nc3+ 23. Kg1 axb6 24. Qb4 Ra4 25. Qxb6 Nxd1 26. h3 Rxa2 27. Kh2 Nxf2 28. Re1 Rxe1 29. Qd8+ Bf8 30. Nxe1 Bd5 31. Nf3 Ne4 32. Qb8 b5 {Every piece and pawn of the black camp is defended. The white queen has nothing to do.} 33. h4 h5 34. Ne5 Kg7 35. Kg1 Bc5+ 36. Kf1 Ng3+ {Now Byrne is hopelessly entangled in Fischer’s mating net.} 37. Ke1 Bb4+ 38. Kd1 Bb3+ 39. Kc1 Ne2+ 40. Kb1 Nc3+ 41. Kc1 Rc2# 0-1

```

# Why is 15. Bxf8 not played?

Here is the chessgames link to the game.

# Answer
> 17 votes
**Short answer**: Since after the **bishop recapture** on `f8` (and not the rook recapture!) white is tactically and positionally completely busted, with *5* active black pieces against a completely *exposed* king in the centre and no foreseeable chance of consolidation in order to eventually benefit from the material advantage.

## **First observations:**

* `15...Bxf8` is with tempo as it attacks the queen on `a3`
* White king is still stuck in the centre and being at least two tempi away from castling, not even sidestepping from the open file with `Kf1` is possible.
* With the bishop recapturing on `f8,` `Bb4` becomes a constant threat, which means `Nxc3` is unstoppable for white as `Qxc3` falls to `Bb4` winning the queen in all ensuing lines.
* Although white is an exchange up temporarily, one of their rooks and the `f1` bishop are completely out of play still and therefore it is in fact black who effectively appears to be material up (with last piece being the `a8` rook that comes into play with check in fact `Re8+`), not in the raw count of pieces but most definitely in terms of the positional compensation.
* Most important consequence of all these observations: black is well in time to prevent white from ever consolidating, which means even without concrete assessment of the different lines we can safely bet that everything's about to fall apart for white quite shortly after `15...Bxf8` as black's initiative on the white king seems to lead to tactically and forcibly winning variations in every scenario.

## **Brief concrete assessment:**

Now let's look at a few candidate lines concretely (*by no means exhaustive, please make sure to check these and the connected sidelines with an engine on your own*)

```
 [title "after 15. Bxf8 Bxf8"]
 [fen "r4bk1/pp3p1p/1qp3p1/8/3Pn1b1/Q1P2N2/P4PPP/3RKB1R w K - 0 2"]

 1. Qb3 Nxc3 2. Bc4 (2. Ra1 Re8+ 3. Kd2 (3. Ne5 Rxe5+ 4. dxe5 Bb4 {and the mating net is set, white's completely defenseless.}) Ne4+ {and black's at least winning the f3 knight after for instance Kc2 and Qa5}) (2. Qxb6 axb6 3. Ra1 Bb4 4. Bc4 Ne4+ 5. Ke2 Re8 {only way to avoid the discovery is to play Kd3 but after Nxf2 Nxh1 we're back to a quite similarly lost endgame compared to the 2...Nxd1 Qxb6 line}) Nxd1 {and black is up a clear piece as white cannot in any way recapture the knight} 3. Qxb6 (3. Qxd1  Qb4+) (3. Kxd1 Qxd4+ 4. Qd3 Qa1+ {and the h1 rook is lost, notice the Bxf7 trick doesn't lead to anything for white.}) axb6 4. Kxd1 Ra4 5. Bb3 Rxd4+ 6. Ke2 Re4+ 7. Kd1 Bb4 {and black's clearly winning considering the bishop pair, the 2 pawns up and a passed one already, the exposed white king under constant threats and the out of play white rook.}

```

these lines clearly demonstrate why the `f8` rook is in fact not hanging and why white's best chances lie in `Bc4` creating Luft on `f1` for the king (or even short castles if black allows on a good day) side-stepping (at first glance) most of the tactical shenanigans we just witnessed after `13...Bxf8.`

```
 [title "15. Bc4 only attempt at consolidating"]
 [fen "r4rk1/pp2Bpbp/1qp3p1/8/3Pn1b1/Q1P2N2/P4PPP/3RKB1R w K - 0 1"]

 1. Bc4 Nxc3 2. Bc5 Rfe8+ 3. Kf1 {and the rest is as you see in the real game, with Fischer's devastating attack despite the tucked away king on f1, which is just too little too late.}

```

# Answer
> 5 votes
Instead of 15... Rxf8 like in your line, black could play 15... Bxf8. Bxf8 attacks the queen, so the queen has to move. 16. Qa4 let c3 uncovered and makes 16... Nxc3 with an upcoming Re8+ possible, 16. Qc1 (the only other square for the queen) should pretty much be lost after 16... Nxc3 (the queen can't take because of Bb4). On 17. Rd2 Re8+ looks strong, and against 17. Rd3 Bb4 looks pretty strong. 16... Re8 could also be strong instead of Nxc3. All in all the white king is very vulnerable in the middle of the board and black can play pretty strong gaining some tempo by attacking the white queen. So black would have a strong initiative for the exchange, which gives compensation at least.

---
Tags: analysis, positional-play, famous-players, planning, famous-games
---


title: Early-game Principles

text:
# Question
Title: Early-game Principles
I am a novice player who is trying to brush up on the core principles for successful chess.

Instead of focusing on specific openings in the beginnings of a game, I am trying to play to certain principles, namely:

* Control of the centre by a combination of pawn and minor pieces.
* Early development of minor pieces
* Not losing momentum, or hindering development, by having to move the same piece twice.

**Specfic Problem:** I am currently having trouble with tripping over myself by moving pieces in the way of each other so that I end up not adequately defending pieces, or defending pieces come under attack. I often lose a pawn in the center which I was trying to defend, i.e. I failed in taking a square I wished to hold (d4, e4). This tends to happen by a pawn being taken and then the attacker pawn is defended by another pawn, so that my developed minor pieces can't retake without losing material in the exchange. So I think I might be pushing forward too early with my pawns. (I usually move e4, then some variation of knights, then bishop. I also don't know where to place my bishops (the only places I know for tactical/strategic advantage are pinning an opponent's minor piece against queen or king, or to aim them at the opponents weakest square (f2, f7).

**General questions:** Are there any other early-game principles? What order do you generally develop? How many turns does it take you to make a push for the centre? What squares do you move your minor pieces to for strategic or tactical opportunity?

# Answer
> 9 votes
You can probably benefit greatly by improving your tactical calculation. Doing some exercises on chesstempo.com will help you get used to calculating out those exchanges. What you are describing seems like a tactical issue and generally can't be addressed using strategic ideas.

That said, a good way to avoid those difficulties may be to specialize in some less complicated openings until you get comfortable with the tactics that appear in the opening. Maybe the London System (`1. d4` ... `2. Nf3` ... `3. Bf4`) for white and the Center Counter Defense for black (`1. e4 d5`). Both have some traps, but there are less to deal with.

Personally, those are the two openings I liked to use to get "used" to chess without having to really deal with the openings much. Especially if you are a more strategic, positional player, these two openings should feel pretty natural.

# Answer
> 3 votes
Aron Nimzowitsch's book *My System* has more early game principles which give excellent guidance. Two important ones which would help you fix your problems are:

* **Over protection**. If you over protect your central pawns then you aren't going to lose them
* **Prophylaxis**. This means trying to anticipate your opponent's plans and good moves and trying to prevent them. This starts by asking yourself after every move of your opponent "Why did he do that?" It is an important step to becoming a better player.

# Answer
> 2 votes
You've given the basic opening principles. Another you might add is early castling to safeguard your king. Also connecting your rooks (by getting the queen out of the way, to c2, d2 or e2 as conditions dictate) ) and moving them to files that are or are about to be open, generally the "d" and "e" or possibly "c" files. Knights before bishops is a good rule, since as you indicate it's sometimes hard to know right away the best square for the bishop. As far as pawns are concerned, if you open with e4, your goal is to ultimately play d4 safely and vice versa. I'd complete my development first before worrying about additional pawn moves though. Hard to give a general answer about pieces getting in each other's way, but I'd say you just have to anticipate your opponent's replies before you move to avoid those. Additional experience should help with that situation. Part of the charm of chess is that there's always more to learn.

---
Tags: opening
---


# Question
Title: What are some good quality magnetic chess sets?
I'm looking for an attractive (probably all-wood external) magnetic chess set that has reasonably strong magnets and pieces of relatively normal size; I've had enough of the chintzy plastic ones with 1/2" kings. I'd also prefer it to be a one-piece board, not a folding one (though that's not important). I was thinking of purchasing one of these:

Link

Link

I was just wondering whether anyone has had experience with these or other similar sets and would like to recommend them for their strong magnets. Again, I'd like its squares no smaller than, say, 3/4". And a folding board is fine, though I'd prefer one with a drawer.

Edit: I'm looking for a set that wouldn't cost much over $50, but if there isn't really a good set available for such a price, I'd be willing to look into higher-priced sets (as in Ed Dean's answer)

# Answer
> 4 votes
After some research, as extensive as possible solely online, and aided by thefind.com, I settled on these sets (click to go to the online store):

Both are magnetic, and are alleged to have strong magnets.

The first is a mere 7.5" board, but it doesn't fold (which I like), and it has a drawer (meaning that I can set up and tear down without pouring pieces all over the place or even move the board). The price: $29.99.

I went for size with the other: a folding board, since the price was much lower for a folding board of that size (12") than for a board with a drawer. This one costs $39.99.

They have a claimed retail price of $79.99 each, which seems a bit exaggerated to me after seeing other stores' prices for similar sets. I would place the value around $65 for the larger and $50 for the smaller based on other prices.

I considered buying their 12" drawer set ($79.00) in lieu of both the above, but decided against it, since it would end up costing more, and at this point I would rather have two sets.

Another set I was seriously considering is sold by another store.

<sub>(source: houseofchessstore.com)</sub>

I like this idea, since not only does it have a handy place for captured pieces to go, it also can be closed up in a certain position to be played later.

I'll update later on how the ones I purchased turn out.

**Edit, a week later:** I've just received the sets, and though one was not the exact set I ordered (hinged w/ board on top instead of a drawer), the sales rep I contacted is going to initiate an exchange shortly. The other set was better than my expectation, with smoothly finished wooden board and pieces, and inlaid wood squares. No magnets are visible, and the pieces fit snugly in the carved felt inside the box. It's a handsome size and convincing weight, and the pieces are the same. I believe I would have paid more for it.

My review of the other set will have to wait until it arrives...

**Edit, two days later:** I talked to the sales rep again, and he let me know that they actually do not have any drawer sets of that size, and that a item number mixup led to advertising of a 7.5" x 7.5" drawer set instead of a 7.5" x 7.5" hinged top set. He offered to pay return shipping as well as the refund, but also gave me the option of keeping the set and letting him send me a 5" x 5" drawer set free of charge or a $20 discount on a larger set. Naturally I appreciated this offer very much, and accepted the 5" x 5" set. So now I will end up with three sets. I unpacked the 7.5" set which I had set aside, and tested it.

The magnets are not as functional as the ones in the larger set, and three of the pieces had virtually no "stick" to the board and would readily slide off when tilted sideways. (They would stick pretty firmly to the refrigerator, though, so that was partially the board's fault). All the rest of the pieces wouldn't move if *carefully* rotated sideways and upside down, but almost any motion while sideways would cause some pieces to slide slightly. Other than that, it is another well-put-together set that seems as if it will last a lifetime.

Now naturally I couldn't live with the three nearly nonmagnetic pieces, so I peeled off the felt of one of the faulty pawns, pried out the magnet, and had a look. It was a cheap, grainy sort of magnet, but strong enough for its size that I almost gave up trying to come up with a better substitute. Suddenly I bethought myself of some old Magnetix kits we had stored away. Armed with pruning shears, I removed a magnet off the end of one of the toys. It was about the same diameter as the chess piece's magnet - a smidgen smaller, but twice as thick, and at least twice as strong. I drilled the pawn with a power drill to make room for the new magnet, fitted it tightly in, so it didn't need glue, and glued the felt back on with white glue. Voila! A pawn resurrected! I did the same with the other two pieces, but after I placed them on the board, I discovered that I would like *all* the pieces to be that strong. For the next two hours, I removed Magnetix magnets, peeled off felt pads, pried out magnets, drilled holes, forced in magnets, glued on pads, and set the pieces on their sides to dry overnight. The next morning, I was suddenly very fond of my chess set. The only drawback to the stronger magnets is that the pieces tend more now to stick to one another if you are not careful with a piece in transit near other pieces. It isn't on the level of a big problem, though, and I like the new magnets much better than the weaker ones. Now I can shake the set while it's sideways, and only the Black king will move (I must have set the magnet too far in).

Bottom line: I would recommend this set in its original form but with the warning that the pieces will not have very strong magnets. Strong enough to carefully turn it sideways/upside down, but not much more.

Later I will review the 5" x 5" drawer set.

**Edit, nine days later:** The 5" x 5" drawer set was much better in nearly every aspect than I expected. The magnets were strong enough to perform well even during such antics as I described for the other two sets. No slipping at any angle, even with moderate shaking. Yet they are not so strong they pose problems in sticking to one another. And, as with the others, the board and pieces are very smooth and pleasantly glossed.

The drawer slides with enough resistance that even when partially open, it cannot accidentally slide out. It can be slid all the way out on either side, free of the board if desired. It has a spring ball mechanism which fits into an internal groove for additional "hold" when the drawer is in its closed position.

I am very satisfied with these sets.

# Answer
> 4 votes
I know you'd prefer a non-folding board, but since you say that's not a deal-breaker, I'll point you to the ChessMate TravelMate Deluxe set. It has nice wooden pieces and quite strong magnets. If you watch the video available at that link, at about 40 seconds in the board is turned upside down and shaken pretty vigorously, and the pieces all stay in place; it's no trick. The downside for the set is that it's pretty pricey, but I do own this one (like in Wes' comment, I received this set as a nice gift) and I can say first-hand that it's a pleasure to use. They also have some other more and less expensive travel sets that I'd guess are of similar quality.

In fact, I see that they have a non-folding set as well: TravelMate Box. It's just as pricey as the one I mentioned unfortunately, and I can't vouch for this one myself, but from their description at least it seems that its pieces have the same material and magnets as the one above.

# Answer
> 2 votes
I'm loving this set at a Dutch / Belgium / German store

The reason for it is that it's small enough for me to take anywhere in my bag. (it travels with me :)). The size of the board is 10" (26cm) x 5" (13cm) as it is foldable. The pieces are wooden, so they look alright although not too big, and the pieces have magnets in them that are strong enough to be held upside down.

Price for this board is around 20 euro, that's kinda the same in dollars. The good thing about this price that if you lose a a piece, it's affordable to buy a new set.

So if, like me, you live in The Netherlands, Belgium or Germany... This is a really nice option.

Rik

---
Tags: equipment, chessboards
---


# Question
Title: Is it still back-rank mate when there aren't friendly pieces blocking?
The definition of the back rank mate is:

> A Back-Rank Mate is a checkmate delivered by a rook or queen along the back rank in which the mated king is unable to move up the board because the king is blocked by friendly pieces (usually pawns) on the second rank.

For example white to move in this position

```
 [fen "6k1/5pp1/8/8/8/3B4/5PPP/4R1K1 w - - 0 1"]

```

King can't escape second rank, is this back rank mate?

What about this:

```
[fen "6k1/5bpp/8/8/2Q5/8/5PPP/4R1K1 w - - 0 1"]

```

What about this interesting black to move situation (its mate), is there a name for this mate?

```
[fen "6kr/5ppp/7N/2B5/8/6R1/8/1K6 w - - 0 1"]

```

# Answer
**First ask yourself *why* the differentiation of a 'back-rank mate' is meaningful.**

Generalized patterns that we call 'tactics' have names because it helps us to learn from them and respond to them. For example, I personally find the distinction between 'pin' and 'skewer' meaningful because it helps to separate the concepts of attacking 'through' either a less valuable enemy piece or a more valuable enemy piece. Likewise, understanding that pins with enemy kings on the other side are 'hard', and pins with enemy knights on the other side are 'soft' helps to make you wary of 'desperado' attacks that might help break your pin.

Really a back-rank mate could be seen as just a partially smothered mate. But it's important to see the distinction because of how common it is, so you can be aware of preparing for it. It is an acknowledgement of the fact that at the start of the game, your king only has 6 possible moves (being on the 1st rank), of which 3 are taken up by pawns, leaving you with just 2 open squares if your other pieces have developed already. Even after you castle, your king can remain vulnerable because it has only 2 squares of freedom, and both of those are on the same rank - meaning 3 of the opponent's pieces can checkmate your king with no support!

**So, is it helpful to consider your examples above 'back rank mates'?** I would argue **yes**. To me, being wary of back rank mates simply means I need to make sure my king has an 'escape path' when necessary; it is not so critical for me to say "back-rank pawn only" mate vs "back-rank my pieces only" mate vs "back-rank-2-of-my-pawns-and-by-the-way-a-bishop-is-attacking-h7" mate. In all 3 of those 'back-rank sub-types', I have failed to provide my king with enough mobility to avoid a common mating pattern.

**Edit to consider your new example of mate with a knight, on the back rank**. I would say that is not a 'back rank mate', because it does not involve an attack along the back rank, by the queen or a rook. Without that key element, the mating pattern is simply very different.
> 6 votes

---
Tags: checkmate, patterns
---


# Question
Title: Leaving the score aside, what are the criteria allowing Stockfish to choose its "best move"?
I'm trying to understand how a chess engine like Stockfish works. I use Stockfish 10 directly, without an UI.

For example, for this position **(white to move)**...

```
r3n1k1/1bpp2pp/pp2p3/2P1P3/R2P4/3B1rPq/7P/1Q3RK1 w - - - 0 26

```

...Stockfish (depth limited to 31) returns the following informations; I only kept the last lines, eliminating those where the depth was less than 31:

```
info depth 31 seldepth 47 multipv 1 score cp -771 lowerbound nodes 86977322 nps 1898570 hashfull 990 tbhits 0 time 45812 pv f1f3
info depth 31 seldepth 47 multipv 1 score cp -761 lowerbound nodes 87198087 nps 1898499 hashfull 990 tbhits 0 time 45930 pv f1f3
info depth 31 seldepth 47 multipv 1 score cp -790 upperbound nodes 99439222 nps 1905696 hashfull 992 tbhits 0 time 52180 pv f1f3 b7f3
info depth 31 seldepth 51 multipv 1 score cp -788 nodes 134293602 nps 1906577 hashfull 995 tbhits 0 time 70437 pv d4d5 f3f1 d3f1 h3h5 c5c6 d7c6 a4h4 h5e5 b1h7 g8f8 h4f4 e8f6 h7h8 f8f7 d5e6 e5e6 h8h5 f7e7 h5f3 a8e8 f4c4 b6b5 c4c2 e7d8 f3d3 d8c8 c2e2 f6e4 d3e3 c6c5 f1g2 c5c4 g2e4 b7e4 e3d4 b5b4
bestmove d4d5 weight f3f1

```

I don't understand what criteria allow Stockfish to say that `d4d5` is the best move. The line corresponding to d4d5...

```
info depth 31 seldepth 51 multipv 1 score cp -788 nodes 134293602 nps 1906577 hashfull 995 tbhits 0 time 70437 pv d4d5 f3f1 d3f1 h3h5 c5c6 d7c6 a4h4 h5e5 b1h7 g8f8 h4f4 e8f6 h7h8 f8f7 d5e6 e5e6 h8h5 f7e7 h5f3 a8e8 f4c4 b6b5 c4c2 e7d8 f3d3 d8c8 c2e2 f6e4 d3e3 c6c5 f1g2 c5c4 g2e4 b7e4 e3d4 b5b4

```

... proposes a score ("cp score") equal to -788 which is smaller e.g. than -771 (see the following line) by example:

```
info depth 31 seldepth 47 multipv 1 score cp -771 lowerbound nodes 86977322 nps 1898570 hashfull 990 tbhits 0 time 45812 pv f1f3

```

**If it is not the `cp score` that is decisive, what is the criterion used?**

Any help would be appreciated !

# Answer
> 4 votes
The first three lines:

```
info depth 31 seldepth 47 multipv 1 score cp -771 lowerbound nodes 86977322 nps 1898570 hashfull 990 tbhits 0 time 45812 pv f1f3
info depth 31 seldepth 47 multipv 1 score cp -761 lowerbound nodes 87198087 nps 1898499 hashfull 990 tbhits 0 time 45930 pv f1f3
info depth 31 seldepth 47 multipv 1 score cp -790 upperbound nodes 99439222 nps 1905696 hashfull 992 tbhits 0 time 52180 pv f1f3 b7f3

```

Are not actually complete searches. The `lowerbound` and `upperbound` following `score cp ...` indicates that the value is not the actual value of the move. Instead, the value is a bound that was obtained when stockfish failed outside of its aspiration window.

When this happens, Stockfish needs to perform a search at the same depth again, with a wider aspiration window. This is why you have 4 lines at depth 31: stockfish searched the position a total of 4 times at depth 31 because it failed outside of its aspiration window 3 times in a row. The first three scores are not exact, and hence only the score from the 4th search (which is exact) is used to determine the best move.

So the criterion used to determine the best move is the internal score of the deepest search which did not fail outside of its aspiration window.

The internal score differs from the cp score in that stockfish evaluates positions with a granularity of 1/256 of a pawn, rather than 1/100 of a pawn. So two positions may have the same cp score, but stockfish may still be able to rank them internally.

The answer changes again when stockfish uses multiple threads. In this case, a voting system is used, where each thread has a different voting weight based on its score and max depth reached.

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


title: Tips to improve my chess

text:
# Question
Title: Tips to improve my chess
I would like to get some advice on how I can get better at chess. I know that it's a lot to ask, but I would like an analysis of what I am doing wrong and in my games. I would also like to know what I should do to practice, rather than improve the tactics or the endgame.

My Lichess ratings are as follows: 1760 for classical games, and 1900 for tactics. The latter is these days quite low but two months ago I peaked 2100. I intend to do more tactics puzzles these days until I reach again 2100.

I am quite good at my openings. Considering the last month, my average centipawn loss is 32.4, though it has usually been a bit lower (around 28). The ones belonging to middlegames and endgames are respectively, 68.2 and 35.3.

As far as endgames are concerned, I studied up to the middle of part six (corresponding to ratings:1800-1999) of the Silman’s complete endgame course, but I admit that I have not been able to test what I learned because most of the games I play are decided in the middlegame and if they reach the endgame, one side often resigns because of material imbalance. I know that I need to refresh this endgame material even if I have not used them so far very much.

Regarding calculation, I have, in my opinion, recently improved a lot as I make the point of finding candidate moves and calculate up to 10 moves deep.

I make the point of analyzing my games after I play them. First on my own, then with the computer and finally, I play the game on board again so I can see if I can use the computer‘s ideas in the game.

In general I realize that there are some mistakes that I make that I can find on my own after playing a game but some middlegame and endgame moves are quite hard for me (not straightforward endgames such as pawn and king against lone king). Plus, I often cannot understand some mistakes (and particularly some blunders which “only” decrease my advantage by 3 points) that Stockfish detects in my games.

Here are some links to recent Lichess games of mine for you to take a look at for my requested analysis:

#1, #2, #3, #4 , #5 ,#6

In case someone needs anything else to ask a more complete question, please do ask.

# Answer
> 3 votes
As as Master here are my recommendations:

**I. Play slow tournament games**

"Slow" because you need to sit there and really think on your own. "Tournament" because you and your opponent have skin in the game and it makes it serious.

Games from such an event are what you then analyse in detail to find your shortcomings. The lichess games you presented are full of elementary oversights.

**II. Play romantic openings**

I am talking about go for the throat openings including gambits. It has nothing to do with the inherit value of these openings and everything to do with developing as a chess player. If you can't play sharp you won't succeed, so spend some time playing this way before you adopt a more positional approach. The games you shared show weakness in combative play.

**III. Take it from a World Champion**

Get a book(s) written by the player who was a world champion, and study one or two games a night. Try to read through the games as if you are playing them. Guess the moves, analyse continuations, and then see what the player does and comments.

Great books are

* "Tal Botvinnik 1960" by Tal
* "Smyslov's 125 Selected Games" by Smyslov
* "My Best Games" by Karpov

and it goes on and on.

**IV. Solve**

Eat tactic and endgame puzzles daily

**Final comment** You shouldn't be spending a lot of time on openings at your rating, but with the romantic openings you are basically studying tactics and developing a sharp vision. Good luck.

# Answer
> 5 votes
You may be able to get some help from the following tips. Not all of them apply to everybody, so you must be able to think for yourself in a critical way, picking up what works best for you!

* First, forget about centipawns! I would suggest to remove computer engine assistance completely if you want to improve your game. The reason is that, more often than not, checking positions with the engine is like copying in an exam. It helps you get the right answer, but does nothing to improve your knowledge. I am not saying that engines are useless for chess training, but I am saying that it's very difficult to distinguish when they should be used. This results in often doing more harm than good (it may help you judge a bad move as bad, but for the wrong reason!)
* Then, you need to work on your tactics. Puzzles and studies are great, but (of course, unassisted) analysis of your own games also plays a role here. I really doubt you can find candidates and calculate accurately up to 10 moves deep. If you really could, you would be a top-tier Grandmaster. Work on finding out what mistakes you are doing without even realizing!
* Once you have a decent tactical skill (which you probably are close to having given your ratings and games), you'll need to work on your endgames and middlegame strategy. Get a book that covers topics like piece activity, central control/counterplay, weak squares, good/bad bishops, open files and so on. Don't just stick to the general tips. Instead, analyze illustrative games in depth to study how those concepts translate into practical advantage. Try to find strategical themes in your own games as well.
* Last, but not least, every time you make a move, it must have a purpose! If it doesn't, then it's a bad move! If the reason is more of an excuse than an actual reason, then it's a bad move, too! (See, for instance, the ...Bxf3 mentioned in DM's answer. What were the reasons/excuses behind that trade?)

PS: If you can afford one, get a professional coach! If they are expensive on your area, go online!

# Answer
> 4 votes
One thing I noticed is that, as Black, you should probably put a priority on castling. For example, move 14 in game 6 - you play a5 (which *hangs* the pawn) rather than playing something like Be7 so you can castle. In game 4, look at the position after 10.O-O. Your opponent is castled, and your entire kingside hasn't moved *at all*. Stockfish evaluated the position as +3.4; you're already lost.

A couple of times in the opening you played Bg4 followed by Bxf3. There wasn't really a good reason for this exchange, and both times it allowed your opponent to develop their queen with Qxf3 while your king was still uncastled and the position was not closed. You might think that it's a weakness for your opponent to have their queen out early, but you can't take advantage without that bishop.

---
Tags: learning
---


title: Stockfish on Android Question

text:
# Question
Title: Stockfish on Android Question
I recently downloaded Stockfish 10 on my android phone and after unzipping the rar file, there were three separate engine binaries and I am wondering which one would be the strongest one to use. The three that were in the folder are stockfish-10-arm64-pgo, stockfish-10arm64v8, and stockfish-10armv7. Which one of these binaries would be the strongest one to use?

# Answer
> 2 votes
Android 32 bits? stockfish-10armv7

Android 64 bits? stockfish-10arm64v8 and stockfish-10-arm64-pgo

stockfish-10-arm64-pgo is faster but also with larger file

---
Tags: engines, stockfish
---


# Question
Title: Are there any illegal positions that are difficult to spot?
I have a question and I'm sorry if it sounds very uninformed, I'm not a professional chess player so my interest is mere curiosity. I was wondering if there are examples of illegal positions that require more than a superficial look at the chessboard to be recognized as illegal.

All examples of illegal positions that come to my mind are pretty trivial.

* A missing king
* Two kings of a color
* Too many pieces considering possible promotions (e.g. 4 queens + 6 pawns)
* Pawns in the first rank
* Pawns in the eight rank
* All pawns in the second rank and other pieces in higher ranks (except knights)

It's very easy to see that these examples are all illegal. Are there any illegal positions that require more insights to spot?

# Answer
> 33 votes
Yes - the less a position looks like a real chess game, the harder it is to spot if it is illegal or not. Sometimes, retrograde analysis is needed to prove a position can be reached in a legal way. For an example, see the starting position of the Horse Concoction by Harry Goldsteen, which can be proven to be legal.

```
[FEN "8/7P/1P5B/2B1Q1n1/3nn2P/1PRnk1nR/3nnnK1/2B1nQBn w - - 0 1"]

```

However, as White's pawns have to have captured at least five black pieces, the same position with an additional black piece is illegal:

```
[FEN "8/1b5P/1P5B/2B1Q1n1/3nn2P/1PRnk1nR/3nnnK1/2B1nQBn w - - 0 1"]

```

# Answer
> 18 votes
If we define "illegal position" as a position that cannot happen in a game using legal moves, I think that the most difficult to spot would be positions that look normal, but are impossible to achieve.

```
[FEN "2k1rr2/pbpq2b1/1p1p1np1/nB1Pp2p/2P1Pp2/2N2NP1/PPQB1PP1/2KR3R w KQkq - 0 1"]

```

For example this position looks legal, but indeed there is no way how this position could happen in real game - all 16 black pieces are on the board and yet white has doubled pawns. There could be lots of such positions in which none of the rules you mentioned are broken and yet, the positions are impossible to achieve, for example:

```
    [FEN "4rrk1/ppp1bppp/2npbn2/1B6/3NP1q1/1P1Q1N2/P1P2PPP/1K1RR1B1 w Qq - 0 0"]

```

There is no way white bishop could get to g1.

```
    [FEN "2krr3/pppbppbp/2n1pnp1/1B2q3/4P3/2N1QB2/PPP1NPPP/R4RK1 w KQkq - 0 0"]

```

There is no way how white could get two white-square bishops. Yes they could promote a pawn theoretically, but the only square where this would be possible is d8 and this square is black. So had they done so the bishop would be black-squared (not mentioning the fact that with two pawns on c7 and e7 there is no way how bishop could get away from there.

```
    [FEN "6k1/p1p1np1p/1p4p1/3Kqr2/8/BQP3P1/P4P1P/1R6 w - - 0 0"]

```

What was the last move? etc.

# Answer
> 6 votes
The final position in this sequence is legal. (See Baibikov, "Length records in 'Last single moves?' problems", A15.) It is remarkable in being the lightest-known position in which the last 17 single-moves can be determined, neither king is in check and it is not specified whose move it is. "Lightness" is decided primarily by the number of pieces and pawns in the diagram position. (Baibikov had a further method of determining which of two positions is the lighter if they have the same number, but that needn't concern us here.)

It can be deduced from the board position that White moved last. While White got into position, Black needed to use up four turns pushing the h7 pawn. Therefore if Black had another turn, Black would have to make another pawn push, beyond the diagram position. Therefore the diagram position is legal with Black to move but illegal with White to move. Similarly, if the black pawn were put on h4 instead of h3, the position would be illegal because Black must have spent only 3 turns pushing the pawn, thus failing to give White enough moves to get into position.

```
[Title "Dmitri Baibikov"]
[fen "8/Ppp4p/rp6/1k6/n7/KPP5/pPP4P/1b6 w - - 0 1"]
[StartFlipped "0"]
[StartPly "17"]

1. h3 {White must spend 4 turns moving this pawn to h6, so must not use the two-square option} Ka5 {unpinning Black's knight} 2. h4 Nc5 3. h5 Ne6 4. h6 Ng7 5. hxg7 h6 {Black must spend 4 turns moving this pawn to h3, so must not use the two-square option} 6. g8=N h5 7. Nf6 {Ne7? h4 8. Nc6+??} h4 8. Nd7 h3 9. Nb8

```

White has 7 units, so Black has made 9 captures. White's a-pawn has always been on a2 or b3. So the black bishop on b1 is not the original c8 bishop, but one created by a promotion a2xb1=B. So this black pawn and the one now on a2 are Black's d and e pawns, which have made 3+4=7 captures to reach a2. Together with a2xb1 and a7xb6, this makes 9, accounting for Black's captures of all White's 9 missing units. (These include the c1 bishop. Thus White made the capture d2xc3 when that bishop was still at home on c1, to be captured later by a black pawn.)

Black has 8 units, so White has made 8 captures. White pawns have made at least 6 captures axb3, dxc3, exdxcxbxa, accounting for all but 2 of White's 8 captures. Black's a-pawn has always been on a7 or b6, so White captured e2xd3xc4xb5xa6.

So White's f, g, h pawns can't have captured more than twice between them. One captured on g7 then promoted to wNb8, and two are missing. All Black's 9 captures were on the queenside, by pawns. So White's two missing pawns promoted so as to get to the queenside to get captured. Black's f, g, h pawns had nothing to capture and so never left their files, and the h-pawn is still on the h-file. So, for White's h-pawn to avoid Black's h-pawn and promote, it had to capture to the g-file. If neither White's f nor g-pawn captured, White's f-pawn couldn't have passed Black's f-pawn and so couldn't have promoted. So one of White's f and g-pawns captured, only once, and this means that all White's captures were by pawns.

Suppose that White's latest capture (the one within the scope of my diagram) was not h6xNg7 but f6xNg7. Then White's earlier moves were by a pawn on the f-file. Black's f-pawn isn't in the diagram, so what happened to it? It had nothing to capture, so never left the f-file. It couldn't have promoted, because White's f-pawn was in the way. But it couldn't have got captured, because 6 of White's 8 captures were on the queenside and the other two were fxNg7 and hxPg (to let White's g and h-pawns promote).

So White's latest capture was h6xNg7. Now the kingside pawns that are on the board are on the same file, so the above difficulty doesn't arise. White played either fxPg or gxPf, then White's f and g-pawns and Black's remaining f or g-pawn promote without capture.

# Answer
> 5 votes
Some positions which you might consider relevant are the answers to "illegal cluster" problems. An illegal cluster is an arrangement of units on squares which cannot be part of any legal position, but if you remove any unit from the illegal cluster, then the result is part of a legal position.

Here's a particularly complicated one:

```
[Title "Dmitri Baibikov, The Problemist Mar 2010, R421v"]
[fen "B7/1np3p1/N1P1p3/RPr1K1p1/pnkp4/P1p5/B1P1P3/RN6 w - - 0 1"]
[StartFlipped "0"]

```

Dmitri Baibikov specifies "Add units so as to make an illegal cluster". In case you want to solve this problem, I put the answer in a spoiler block:

> (Answer and analysis by Gerd Wilts. I have adapted his notation so as to notate forwards moves; he notated retractions. See P1192196 at PDB.)
> Add wRb2, wPg6, bQb3, bBd5, bNb8.
> Retro 1. ... Nd6-b7 2. Bb7-a8 N~ 3. Bc8-b7 N~ 4. Bd7-c8 Nf1~ 5. Be8-d7 f2-f1=N 6. Bf7-e8 f3-f2 7. B~ f4-f3 8. B~ f5-f4 9. Be8~ ??? {Black's pawn can't be on f6 because it would check} 10. e7-e8=B f7-f5 11. f6xBe7 (critical position) Bf8-e7 12. Kf5-e5 e7-e6+. White then uncaptures dxcR and unpromotes a R on h8, Black uncaptures bxc (B,Q) and hxg (Q,B). But getting from the diagram (after adding units) to the critical position, with Black to retract in both, White necessarily makes an even number of moves and Black an odd number, and neither side can change parity, so the first position is illegal. Removing bPa4 would legalise as White could change parity with Ra4. If we add bRb3 instead of bQ, then removing wPa3 would not legalise as after retracting n.Ra3+ Rb3, bRa3 could not escape to b2.

So the answer to the above problem is an illegal position which cannot be made legal by adding more units. (In any case no more White units can be added because White has 14 and black pawns on c3 and g5 captured the other 2; and not more than one Black unit, because Black has 14 and White's d-pawn now on c6 captured one.) But adding a different set of units might produce a legal position.

# Answer
> 3 votes
One of the most irregular rules says you cannot castle to escape check. You must move your king, block the check, or capture the checking piece. So, if a king is in check and castles it would not be visually so noticeable.

# Answer
> 2 votes
A triple check hasn't been mentioned here, but it's appeared here: Is triple check possible?

@MeniRosenfeld's example 4a covers this but brings up one concrete case that could catch people napping, because without doubled pawns, it might initially seem like there are no captures. Of course, it would have to be disguised a bit better, maybe with white pawns at d4/e5 and black at d5/e4:

```
[Title "pawn switch"]
[fen "rnbqkbnr/p1pppppp/8/1P6/1p6/8/P1PPPPPP/RNBQKBNR w - - 0 1"]
[StartFlipped "0"]

```

And to riff on the entombed bishop from @AlexPetrov's second example,

```
[Title "jumpy rook"]
[fen "7k/8/8/8/p1p5/PpPp4/1P1P4/2B2RRK w - - 0 1"]
[StartFlipped "0"]

```

The bishop can never have moved, so the a1-rook could never have jumped over it, either. We actually do need both white rooks on the board for this position to be illegal, because it's possible a knight could've gone to b3 and taken the rook on a1 (or a2 or b1, if the game was really weird) and retreated.

I suppose false-flag illegal positions (such as without the rooks) would be their own puzzle.

ETA: Evargalo makes a good point about underpromoting rooks. I should have kept all White's pawns on the board just to make sure. But then the position would seem even more contrived.

---
Tags: illegal-move, retrograde-analysis
---


# Question
Title: Python-chess : how to get a list for the best engine moves
I am working on a simple cheat detection script to find if a user used one of the top engine moves in a game, so I found this great python-chess library Additionally, I found this example to getting the moves score. But that topic is an old version of the lib so I tried to update the script. However, I keep getting errors, and I don't know how to get the scores in the right way.

```
import asyncio
import chess
#import chess.uci
import chess.engine
import chess.pgn
import io
#Let's try our code with the starting position of chess:

fen = 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1'
board = chess.Board(fen)

#Now make sure you give the correct location for your stockfish engine file
#...in the line follows: e.g., /home/.../stockfish_6_x64

engine = chess.engine.SimpleEngine.popen_uci('/home/shar/Desktop/cheat detect python/stockfish-10-linux/Linux/stockfish_10_x64')

if board.turn: print( 'White to move');
else: print( 'black to move');

for el in board.legal_moves:

    pgn = io.StringIO(board.san(el))

    thnwpgntofen = chess.pgn.read_game(pgn);
    nwinfo = engine.analysis(thnwpgntofen.board());

    print(nwinfo["score"])

    print("-------------------------");

```

I get this error after running my code:

> Traceback (most recent call last): File "prntengmv.py", line 37, in print(nwinfo\["score"\]) TypeError: 'SimpleAnalysisResult' object is not subscriptable

# Answer
> 4 votes
As per: https://python-chess.readthedocs.io/en/latest/engine.html#indefinite-or-infinite-analysis

`engine.analysis(board)` now returns an `AnalysisResult` object, which has the property `info` that you want.

So instead of:

```
nwinfo = engine.analysis(...)
print(nwinfo["score"])

```

You would loop over `info` in the `AnalysisResult`, and print the score property from each element:

```
with engine.analysis(...) as analysis:
    for info in analysis:
        print(info.get("score"))

```

However, your use case looks like it may benefit from `engine.analyse` more than `engine.analysis`.

---
Tags: engines, programming, python
---


# Question
Title: Can you manually type moves into Arena? (copy pasting notation)
Is there a way to copy/paste a game into arena? I know how to load a PGN, but suppose I have: `1. d4 Nf6 2. c4 g6 3. Nc3 Bg7 4. e4 d6 1-0` as my game. Can I copy paste this anywhere to get it loaded into the GUI?

# Answer
> 1 votes
PGN file format is a simple text format.

https://en.wikipedia.org/wiki/Portable\_Game\_Notation

So ideally you should be able to save your text as pgn and import in GUI.

However it depends on GUI how strict the rules are for importing pgn.

For example, you can copy paste your text or import your pgn here and it works perfectly.

https://lichess.org/paste

---
Tags: arena
---