# Question
Title: Is 1. d4 Nf6 2. Nf3 e6 3. c4 d5 called Queen's Gambit Declined when there is no gambit offered, let alone declined?
I understand that the opening 1. d4 d5 2. c4 e6 3. Nf3 Nf6 is called Queen's Gambit Declined. But how about 1. d4 Nf6 2. Nf3 e6 3. c4 d5? There is no gambit offered, let alone declined. Is it still called Queen's gambit declined?

# Answer
> 3 votes
They reach the same position, so they have the same name. It wouldn't make sense to call the same position differently depending on the moves that lead to it. **1.f4 e5 2.e4** is a King's gambit, not a declined From's gambit. **1.e4 c6 2.d4 d5 3.cxd5 exd5 4.c4 Nf6 5.Nc3 e6 6.Nf3** is a Tarrasch Defence despite having started as a Caro-Kann

# Answer
> 9 votes
Yes, it is still called the Queen's Gambit Declined. That's just the name of the system, regardless of the move order used to reach it. However, it is not the QGD before Black chooses to push 3...d5.

# Answer
> 1 votes
This is a transposition, you have to think about the pawn structure instead on focusing on the concrete order, there are thousands of different ways of getting to the same (or quite similar) positions

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


# Question
Title: I read that Mikhail Tal claimed to have been able to see 50 variations ahead in a game. Any thoughts on this possibility?
Mikhail Tals' books on chess. Learning/analytic chess theory. Perception and intuition in the development of strategic and tactical chess play.

# Answer
> 4 votes
Note that "number of moves ahead" is not necessarily a great proxy for "number of positions considered". An open board with no impending threats has many possibilities of what might be the "best" move, and will require a player to analyze a wide, but shallow tree of possibilities. A board with few pieces and many threats has relatively few "good" (or even legal) moves, so a player can look farther ahead down a narrow but deep tree of possibilities. In some cases, the tree becomes a path - there is only one move to make. This question, for example, shows games with many repeated checks, making the tree of potential moves very narrow indeed.

It seems that most high-level chess players tend to think 20-40 moves ahead, depending on the board state. It's not unreasonable to think that someone could think 50 moves ahead in very particular situations, where the next few moves are "obvious" or even forced. But to be able to consider 50 moves ahead in *all possible situations* is likely beyond a human's ability.

# Answer
> 2 votes
**"50 variations"**

This is very possible. I think that the key to understanding this is to know the difference between *variations* and *moves ahead*.

**VARIATIONS:** Consider any move. What can the opponent do in return? Does he have 2 choices? 30? Each of his choices makes a variation. If you have a candidate move and you opponent can reply in 10 possible ways, then you see 10 variations.

**MOVES AHEAD:** I play e4. Then I think that you will play e5, I Nf3, you Nc6, I Nc3, you Nf6, I Nxe5, etc. (Halloween Gambit). This involves thinking 6 moves ahead on a single variation.

So 50 variations? I think that you can do that. In most positions you have about 3 candidate moves. Consider each move; think about three or four moves ahead for each one. You will certainly run into variations. To make 50 variations, your three candidates will have to have about 16 variations each. Each candidate is a variation of of the current position. In our case of 3 candidates, each candidate will demand 4 variations which have 4 of 5 variations each to make 50 variations (4x4x3 = 48). So you see, you variations add up rather quickly. I think that to make 50 variations, you would have to see only about 4 moves ahead in most positions.

# Answer
> 1 votes
In my opinion, this is totally possible, as it has been said above good players have the ability to play games blindfolded, and players such as Tahl are skilled enough to play several blindfolded games at the same time. But in a practical way, calculating 50 moves ahead doesn't make any sense as the possible variations for 50 moves are infinite, even though good players have the ability to go this deep in a concrete line, they don't have to because their instinct will tell them much before whether that's a good line without having to go that deep.

---
Tags: analysis, theory
---


# Question
Title: How should one decide which rook to put on a central file?
How should one decide which rook to put on a central file? I usually just move the one which is closer to the file, unless there are weak squares in my position that one rook is defending. In positions where there are no weak pawns, how should I decide whether to move the rook of the side to which I castled or the other?

# Answer
Essentially, you should ask yourself a broader question: where should *both* of my rooks go in this position? There might be another (half-)open file which can be used by the other rook. If there's only one open file and little chance of another one opening or a pawn needing extra protection, it might not even matter which rook you use, since it's rather likely for the rooks to be doubled up on the same file anyway.

```
[FEN "r4rk1/ppp2ppp/3p4/8/8/3P4/PPP2PPP/R4RK1 w - - 0 1"]

```

In a position like this (ignoring the position of other pieces) it's more common to move Rfe1, since the chance that one of the a, b and c pawns needs extra protection *combined* is greater than the chance that f2 becomes weak. Indeed, that's the nearest rook, as you already mentioned.
> 8 votes

# Answer
Try to determine which rook will be better off, if left on its current square. Here are some examples (for these I'll assume you have rooks on f1 and a1).

* As you mentioned, a rook could be defending a weakness right now.
* Could the file the rook's currently on end up being opened? For example, if White's f-pawn has a good chance of being exchanged, maybe it's best to keep the f1-rook where it is.
* How much space would the rook not on the open file have - in general, this is one of the biggest considerations. For example, if you played Rae1, the f1-rook is stuck. But if you played Rfe1, the a1-rook still has room to move.

There are also other considerations. For example, on which side of the board do you want to concentrate your forces? If you're launching a kingside attack, moving the a1-rook to e1 would increase your influence in that sector.
> 6 votes

# Answer
That's a good question, very difficult. I used to spend a lot of time on such a decision. I remember once when a similar question was asked to GM Vachier-Lagrave, something like why did he put the f1 rook in the open file d1 instead of the a1 rook. He replied: I don't think much about it because most of the time in complex positions we don't know which one to choose anyway! At first I was upset by this answer because I expected to learn something new, but his answer was actually very useful to me because if in complex positions a top rated player doesn't know, I won't know either. So now I don't give this decision too much thought!

Let me add however that **details matter** and in some positions there is a clear choice.

Take a very recent example from Maxime Vachier-Lagrave vs Teimour Radjabov, FIDE Chess.com Online Nations Cup (2020).

```
[FEN "r1b2rk1/pp2bppp/4pn2/2n5/2B2B2/2N1PN2/PP3PPP/R2q1RK1 w - - 0 11"]
[title "Vachier-Lagrave vs Radjabov Online Nations Cup (2020)"]

1.Rfxd1 (1.Raxd1 b6 2. Bd6 Bxd6 3. Rxd6) b6 2. Nd4 (2.Bd6 Bxd6 3.Rxd6) Bb7 3.Rac1

```

In this position, taking in d1 with the rook f1 looks very natural to me because eventually you want the other rook to come in c1. Vachier-Lagrave played `Rfxd1`, later followed by `Rac1`.

However, if in the previous position your plan is to try to take possession of the "d-file" by later playing Bd6, then taking d1 with rook a1 or rook f1 doesn't matter much (see the variations). In this context, I now save time by applying the advice of Vachier-Lagrave.
> 4 votes

---
Tags: positional-play, castling, rooks
---


# Question
Title: Why is the king powerless and the queen powerful?
Historically, real kings were powerful (Alexander the Great, Napoleon Bonaparte etc.) and women were powerless. The game of chess began in Asia, some say, and the women were definitely powerless there. Maybe Cleopatra was powerful, but still doesn't explain why the people who created modern chess made the king so powerless and hopeless, hiding behind his army and his queen

Is it because of Queen Mary, aka Bloody Mary Was she the one who influenced the people who created the modern chess? Is she the reason why kings are hopeless and queens are ruthless?

# Answer
> 20 votes
Practically speaking, if the king were any more powerful, checkmate or capture would be impossible.

The Queen originated as the Advisor. The Advisor was powerful, but not as powerful as the modern Queen, however. Why did the Advisor become the Queen? Having more than one Queen per side would debase the game, and there are two each of the other pieces. Thus, the Advisor is the only candidate.

Why is there a piece with huge Queen-like powers at all? It looks like the Europeans wanted to speed the game up. So they made a more powerful Queen, pawns started moving 2 squares on the first, and castling was created.

Finally, I am not sure that the piece we call the Queen is called that in other languages. The game and its ancestors have piece names like camel, elephant, advisor, minister, horse, etc.

# Answer
> 10 votes
As a Turkish, I can say it's not a queen in original, we call it as **Vizier**.

We may say that the grand viziers used to manage all the things about country like taxes, wars, staff etc. There were so many viziers in the eastern history, who were more powerful and effective then shah (king) like Nizam al-Mulk.

So, I can say that it's probably caused by Asian and Middle-Eastern culture.

Also, you must look here.

# Answer
> 10 votes
The king is not powerless! So much so that when the king is check mated the game ends so, and a victor is declared. Is the king powerless??

I think you are mixing mobility and reach with being powerful; looks like because of the mobility and reach of the queen it is somehow powerful where as the king is powerless but, that's somehow incorrect. You can see the power of the king increases as the game enters the ending stage and less pieces exist on the board; even though king's reach is short the king becomes one of the most powerful pieces on the board in the endgame (This is one of the most beautiful and amazing things a like about chess; the dynamics of power and value is not static, it changes and evolves as the game progresses).

For instance, notice that the queen alone cannot deliver check mate in a Queen+King vs King; the queen needs help of another piece to be able to deliver check mate against a lone king.

As a reference for players relative value of pieces is given and the queen carries the biggest value but, the king is given infinite value or no value though, an explanation being that when the king is captured or check mated the game ends.

Some times in a game of chess it can happen that a simple pawn can become even more powerful than the queen. Many studies show how the power of pieces changes depending on the specific position and circumstances on the board.

# Answer
> 6 votes
The queen used to be a ferz, a variant of the word vizier (and curiously close to its meaning of advisor), which could only step one square diagonally. So originally the piece that became the queen was less powerful than the king.

# Answer
> 3 votes
Origins of chess according to Wikipedia:

> The game originated in northern India in the 6th century and spread to Persia. When the Arabs conquered Persia, chess was taken up by the Muslim world and subsequently, through the Moorish conquest of Spain, spread to Southern Europe.

And it's just not on wiki, this is very widely accepted as a fact.

In India, it was popular by many names throughout the times, as there are multiple languages spoken here. So, if you ask a Indian player he might tell you 2-5 synonyms of each piece on the Board. And names of these pieces range from animals in the jungle to people in a King's court yard. For Example: *Hathi-Ghooda-oont* (Hindi words for Elephant-Horse-Camel) and queen was known as Mantri-Rani-Vazir ( The first word translates to a Minister (serving directly under king as his second in command), second word translating as a queen, the third word coming from middle east regions meaning Commander/general or simply a minister )

So, Basically the game was pretty much the same but different linguistic groups or different classes of society made their own names for the sake of simplicity. A lot of which I believe are lost. Only the popular ones remain. Naturally, the upper class of the society's terms are with us now as they were well documented.

Coming to the powers that specific pieces possess.

King: Ever since the beginning of the game as well as human society the people on the top were considered to be precious. The kings and commanders swore oaths to protect their country and soon they became the symbols of peace and progress of the country. If they were taken down everything went down to hell. For each sentence from above you'll find numerous examples. Those that come to mind:

1. Sati: When kings died their wife(s) and their helpers used to commit suicide.
2. Second Battle of Panipat : In 1556 at the second battle of Panipat, where the teenage Akbar is watching Hindus and Afghans under King Hemu being trounced by his own Mughal army. A Mughal archer gets Hemu in the eye. Hemu falls on the ground and seeing the King fall down his army just runs away even though they were far more superior in numbers and equipments.

**As to why kings are shown weak when they were so important:**

* Not all kings were powerful, healthy and strong. Some were weak/pathetic but still due to their lineage they ruled for years.
* See it from kings point of view "No king whats to work from himself when he is got people to work for him"
* Even if kings were powerful, they were still symbols and leaders to their people hence they were protected. Like, if a king looses, an army looses , land- lives are lost , people are looted, women would get raped, children will get murdered or get recruited to join army at early age,etc.

You are looking it just as a meaning of a single word king. But that wasn't the ground reality. And chess is based on real life scenarios. I know many countries don't have history in syllabus or they don't have that big of a history to tell... I recommend you read history of India for such examples or even French history to some extent.

**Queen Being Over-powered** : Again coming back to how people choose different name for their pieces according to their convenience. The piece currently known as Queen was created keeping in mind the actions/functionalities that a Mantri/Vazir provided a King.

King was used as a face/symbol , he didn't do much, queens didn't do much either they had people for each work they could possible need to do. For queens there were *dasi* (Female servents), for king there were *das* (male servents) and *mantri* . *Dasi and Das* were chosen to work for king and queen for their whole lives and they had no say what so ever. Where as *Mantri* were chosen either on basis of their high intellectual skills or high lineage. They were given different powers over the state and they exercised this power under the name of the King.
And it is still followed, like in UK, Queen is the supreme Leader but her powers are exercised by the Prime Minster under her name. Same situation is in India, The president signs all the documents presented to him by the prime minister but he cannot implement anything on his own.

Modern chess just happens to have the name for the piece as queen, as it is both convenient and relate-able to the king. In addition to that there **can be** so many situations that make this choice apt:

1. Feminism
2. Romanticism
3. Queen makes it feel much personal(to the board and player) than using the word Minister., etc

> And women were powerless, well the game began in Asia, some say and the women were definitely powerless

That is so not true. Women were part of making in India far before any western Civilization saw a women leader.

India: "Razia Sultana (1205–1240) became the only woman monarch to have ever ruled Delhi. The Gond Rani Durgavati (1524–1564) ruled for fifteen years before losing her life in a battle with Mughal emperor Akbar's general Asaf Khan in 1564. Chand Bibi defended Ahmednagar against the powerful Mughal forces of Akbar in the 1590s." -Wikipedia

West: "Mary Tudor was the only child of King Henry VIII and Catherine of Aragon to survive into adulthood. Mary took the throne in 1553, reigning as the first queen regnant of England and Ireland." - Wikipedia

Modern Example: For 1 Queen that ruled colonized India there were 6 that fought against her.

Again that's a different question altogether but read Indian(Asian) History to know more. Also, please don't don't mix opinions with facts (specially prejudiced). Next time someone reads it from here he might take it as a fact.

Thank You

# Answer
> 1 votes
The Question relates to more of a naming convention and interchanging Queen with Wazir . Wazir or the Minister or the General of the Army is all same here in Chess .

The rules of the game have been quite similar to the ancient civilization . The King is actually powerful and has the ability to direct all instructions to win the game or battle . The King belongs to the Throne and without him the Kingdom is lost . If the Army General gets killed their may be a new appointment or without him also the battle can be won . e.g. in chess Pawn gets promoted to a Queen so a valiant soldier can be designated as a Queen. If you watch some historical movies like Troy / Gladiator / Mahabharata you would see that the Kings always stay behind and the main battle would be somewhat far from his radius . I do not disagree to the fact that Kings never participated from the front in battle fields but their always used to a small force of gallant soldiers who would protect him as like Castling in chess.

Technically the Chess Queen or the Wazir/ General can cover more squares on board which infers that the General like Hector/Achilles/Maximus/Arjun/Karna were more adept warriors and could kill many soldiers at once .

So the Question is quite clear as it is the Chess King who is technically powerless because it grounds one square at a time but in real as they were not better warriors than the Queen but had the ability to direct all orders and could instruct every piece to be sacrificed and fight till the end to save the King from getting checkmated .

# Answer
> 1 votes
The king in a chess game is far from powerless. Of course it must be sheltered in the early going to prevent its being checkmated, but as the game progresses to an ending with the removal of the stronger pieces and it's safe and in fact necessary for the king to enter the fray, it's as strong as a knight or bishop. In the early years of chess, the queen could only move one square diagonally, but when later revisions were made to speed up the game, its power was increased dramatically to its current level. As best I am able to determine, the queen gained power in concert with traditions of queenly rule in Europe. Perhaps this also reflected the perception of many men surrounded by strong females that women actually held the power, even if not wielded through the sword, relegating the king to a weaker status.

# Answer
> 1 votes
I believe that the origin of "King" and "Queen" units were the King's and Queen's *Guards.* In either case, they were "picked" troops.

The "king" is just the king and his personal bodyguard. These might be the best 500-1000 troops in the army, which would give them approximately the value of a "piece," a slightly larger unit commanded by a knight or bishop (but with inferior troops).

The Queen's *guard,* was an honorary unit consisting of the remainder of the best troops, basically the "flower" of the army. These troops were more numerous and better trained than the troops in units led by the other officials, which is why the queen's regiment was the most powerful. As I remember, the "three musketeers" belonged to the "queen's" guard. The queen was the titular commander but her "duties" were actually taken over by a high-ranking (male) noble. A pawn that "queens" gets to become this noble (or to have a new "queen's guard" formed under him if the first one is still on the board).

# Answer
> 0 votes
To me, it's a no-brainer. Just ask yourself, who is really in charge of the household in every culture of the world? The king is probably not at home or drunk. If I was a king and my people would play a game with a powerful advisor I would command that the advisor should become my queen. Advisors are probably more keen on coups than the king's queen.

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Tags: rules, history, queens, kings
---


title: Stalemate v/s Checkmate

text:
# Question
Title: Stalemate v/s Checkmate
**I am unable to understand why Photo 1 a stalemate and Photo 2 a checkmate.**

1. > ***PHOTO 1***

---

2. > ***PHOTO 2***

# Answer
> 1 votes
Checkmate: When the king is under attack but there is now way to defend it.
Stalemate: When the king is not under attack but none of him or his army can move.

King Can move one square at a time. So just look at one place around the King. With the above definitions.Also, a king can never go on a square that is attacker/controlled by an enemy piece. It Will be clear.

For figure 1. All the neighboring squares of the king are already under attack so king can't go there, only other piece on the board is a pawn which is blocked by the king himself(pawns move forward only unless capturing in which case they move diagonally forward instead of straight forward). Hence, the king or the pawn cannot move hence stalemate.

For figure 2. All neighboring blocks are already under attack plus the king is also under attack hence black has no move to play. So, its a check mate.

# Answer
> 1 votes
In both photos Black has no moves available, but the difference is that in the second photo his king is attacked (by White's queen on f6).

---
Tags: rules, checkmate, stalemate
---


# Question
Title: Why does the FIDE rating table go beyond 400?
The FIDE rating regulations say:

> 8.5 Determining the rating change for a rated player
>
> 8.51 For each game played against a rated player, determine the difference in rating between the player and his opponent, D. \[...\]
>
> 8.54 A difference in rating of more than 400 points shall be counted for rating purposes as though it were a difference of 400 points.
>
> 8.55 (a) Use table 8.1(b) to determine the player’s score probability PD \[...\]

But table 8.1b (which seems to be used only for this purpose) contains entries that go higher than 400. What use are those entries? Why are they there in the first place if they cannot be used?

# Answer
> Why are they there in the first place if they cannot be used?

They were there in the first place because they *were* used. The 400 point rule came later.

> What use are those entries?

They provide interesting historical context which makes it easier to answer questions like this.

Perhaps a better question would be, why are they still there, or why weren't they removed when the 400 point rule was introduced. There are two obvious answers:

1. Inertia. It would take effort to remove them
2. Efficiency. If the 400 point rule is rescinded at some stage then the entries required are already there.
> 9 votes

# Answer
Table 8.1(a) is also used by reference in the title regulations. To achieve a GM, IM, WGM, or WIM norm, a player must have a performance rating over a certain amount, and the performance rating is calculated using this table. Unlike the rating regulations, the title regulations do not limit the ratings difference to 400 points, so the entire table is used.

Table 8.1(b) is pretty much the inverse of 8.1(a).
> 8 votes

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


title: Blundering phase

text:
# Question
Title: Blundering phase
I have played more online Blitz recently and it was quite some fun, until I encountered what I would call the "blundering phase". Every once in a while, my chess ability takes quite a hit when I apparently lose my ability to think properly. I have lost about 100 rating points online. In many games, I get a winning advantage, only to throw it away with utterly stupid mistakes. I do not know what the root cause of this is, could it be psychological? I'm doing daily tactical exercises between 20 minutes and one hour, so that can't be it. Do you have experience with this and maybe can propose a remedy that has worked for you?

# Answer
You are probably just tired. Go for a walk, sleep well and come back the next day. It could also have an impact on your confidence (making a mistake on this game will thus make you more likely to make another mistake on the next one)
> 3 votes

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Tags: psychology, blunder
---


# Question
Title: How does Elo rating gain scale with games played?
I only take two players starting out at 1500 Elo and have them play against each other with one player winning all games. Also I leave out any artificially introduced cut-offs.

So the winner is constantly gaining rating while the other player is losing Elo rating. The gain is decreasing because the rating difference of the players increases.

How does (mathematically) the raiting gain scale with the number of games (n) played for large n?

# Answer
> 6 votes
It kind of depends exactly what you mean by artificial cutoffs. There is one explicitly stated artificial cutoff in the FIDE rating regulations. That says that if the rating difference is greater than 400 it will be treated as 400. But there is another hidden cutoff. The actual elo algorithm for calculating expected score or scoring probability involves power functions but FIDE provide a look-up table with approximations. This bottoms out when the rating difference is 735 with the expected score of the stronger player at 1.

So, if the 400 point cutoff is excluded but the exact FIDE algorithm with its table of expected scores is used then the maximum rating difference is 735 points and once the two players' ratings reach 2235 and 765 further wins for the stronger player will not change ratings. That is part of the reason the 400 point rule was introduced.

If, however, you are not talking about FIDE's implementation of the elo algorithms then the problem becomes a purely mathematical one. I look at the algorithms below.

The formulae for working out rating change for elo ratings work like this:

Suppose the initial ratings of the two players are r(1) and r(2) and their recalculated ratings (which we want to work out) are r'(1) and r'(2).

First we need to calculate a power function for each initial rating to use to calculate the expected result of the match. So, call these power functions for the two players R(1) and R(2) and their expected scores E(1) and E(2).

So -
R(1) = 10^(r(1)/400) and R(2) = 10^(r(2)/400)

And -
E(1) = R(1) / (R(1) + R(2)) and E(2) = (1 - E(1)) = R(2) / (R(1) + R(2))

Now let S(1) = player 1's score in the game (going to be 1 in this case) and
let S(2) = player 2's score in the game (going to be 0 in this case) then

r'(1) = r(1) + k * (S(1) – E(1)) and
r'(2) = r(2) + K * (S(2) – E(2)) where k is the k factor

If there are no artificial cutoffs then the two ratings will eventually reach 3000 and 0 (with the same k factor for both, one player's rating gain is the other player's rating loss).

What happens in the next game?

Well r(1) = 3000 and r(2) = 0 so -
R(1) = 10^7.5 = 3162276.6 (to 8 sf) and
R(2) = 1
E(1) = 0.999999968
E(2) = 0.000000032, so
r'(2) = -0.000000032\*k

The second player's rating continues to decrease and goes negative.

I'm fairly sure that as these algorithms are power function based the limits will be power function limits, i.e. the first player's rating will tend to infinity and the second's to -infinity

# Answer
> 4 votes
Indeed the limit of this scenario would be infinity for the perpetually winning player. This is because FIDE has a rule saying that if one player is rated more than 400 points higher than his opponent, their difference should be set to 400 when calculating rating gain/loss. That means no matter how weak the opposition is, our winning player will receive minimum 0.8 rating points for winning.

See this discussion as to why this rule exists: Why is there a minimum rating gain when you win?

# Answer
> 3 votes
If we work solely from the standard mathematical formula for Elo ratings, it's possible to prove that the winning player can get an arbitrarily high rating, but that it'll probably take exponentially long (i.e., the winning player's rating increases logarithmically).

I'll suppose that the initial Elo rating of the two players is 0, not 1500, because it makes the math simpler. (If this bugs you, just add 1500 to every number below.) Let r(n) be the rating of the winning player after n games, so the rating of the losing player is -r(n). Then in the (n+1)st game, the rating difference is 2r(n). By the calculation given in Brian's answer, r(n) obeys the formula

r(n+1)-r(n)=K/(10^(r(n)/200)+1)

with r(0)=1.

This recursion is painful to solve explicitly, but we can use a differential equation to approximate the solution. Explicitly, let f(r)=10^(r/200)+1; then the above recursion can be approximated as

r'(t)=K/f(r(t)).

Intuitively, passing to the differential equation is considering the limit of the process where we repeatedly play twice as many games, but with a K-factor that's half as large. Every time we do this, we slow down the rating growth a little bit, because the winning player has a higher rating as they play the second game in each pair than they do in the first game, so the second game leads to slightly less Elo growth than the first game.

The differential equation r'(t)=K/f(r(t)) is a separable differential equation, which can be solved. I won't bore you with the details on a platform that doesn't let me write formulas, but the solution turns out to obey the equation

t=(200e^(r/200)-200+r ln 10)/(2K ln 10) .

Notice that this is an equation for t (the number of games played) in terms of r (the rating of the better player). There's essentially no nice way to invert this equation to write r in terms of t. However, we can notice that t is well-defined for any positive r, and is an increasing function of r. So, for any given rating, we can find the amount of time required to achieve that rating, which means it's possible to achieve arbitrarily high ratings.

But since t is an exponential function of r, the amount of time taken may be exponentially long; that is, r will grow logarithmically over time.

This argument shows that the winning player's rating can grow arbitrarily large in the limit where we played many more games, but with a correspondingly smaller K-factor. But as we argued above, the winning player's rating increases faster in the original setup than it does in this limiting setup. Since ratings can grow arbitrarily large in the limiting setup, this means that ratings can also grow arbitrarily large in the original setup.

I'm reasonably certain (but have not proved) that this growth is still logarithmic.

---
Tags: rating, elo, mathematics
---


title: Free opening name database?

text:
# Question
Title: Free opening name database?
Is there a database available that the gives you the names of common openings? "Ruy Lopez", "Sicialian", "Queens Gambit", etc. Ideally it would just be a simple map of the opening PGN to the common name.

# Answer
There is an "eco" GitHub project available which I believe, based on the name, is based on the *Encyclopedia of Chess Openings*.

This project used to provide a JSON file with all openings, but now provides a set of tab-separated files with columns for ECO code, name, FEN, and moves.

To give you an idea of the format of the file, here's the entry for *Ruy Lopez: Marshall, Main Line, Spassky Variation*, which happens to be the longest opening in the file:

```
C89     Ruy Lopez: Marshall, Main Line, Spassky Variation       5rk1/5ppp/p1pbr3/1p1n3q/P2P2b1/1BPQB1P1/1P1N1P1P/R3R1K1 w - -   e2e4 e7e5 g1f3 b8c6 f1b5 a7a6 b5a4 g8f6 e1g1 f8e7 f1e1 b7b5 a4b3 e8g8 c2c3 d7d5 e4d5 f6d5 f3e5 c6e5 e1e5 c7c6 d2d4 e7d6 e5e1 d8h4 g2g3 h4h3 c1e3 c8g4 d1d3 a8e8 b1d2 e8e6 a2a4 h3h5

```
> 7 votes

# Answer
I have a CSV file with 2000+ openings in it, with their ECO codes, all names, and moves in SAN notation. You can find it on GitHub here: https://github.com/Destaq/chess\_graph/blob/master/elo\_reading/openings\_sheet.csv.
> 5 votes

# Answer
Lichess provides an online database in the analysis board which will tell you the name of the opening in the chess board. However, chessbase is a much more powerful tool, it provides an online database and you can also load any database you can find on the internet (chessbase will automatically display the name of the opening on the board). Moreover you have the option of creating your own database, with your own games or games of other databases (or both).
> 2 votes

---
Tags: opening, database
---


title: Scid chess can not save

text:
# Question
Title: Scid chess can not save
I try to save color marking, etc. but the program gives error messages.

“The requested function is not supported by this type of database.”

Can I save this? So far it doesn’t save, amd when I save it won’t save markings.

# Answer
> 2 votes
I figured it out a few minutes later Go to Menu at top “game” then “Save: Add New Game” Add a new tag or title and will show in game list so you can pick which one you want! Saves markings and you can edit tags and of file after

---
Tags: scid
---


title: What moves solve this mate in 2?

text:
# Question
Title: What moves solve this mate in 2?
It’s White to move and mate in 2 moves.

```
[FEN "7r/1p3Q1p/2q5/3bk3/1Q2p3/2P5/r2P2PP/2KR4 w - - 0 1"]

```

# Answer
White to play checkmates in 2 with 1 d4+! exd3 e.p. 2 Qbf4#.

Black to play cannot checkmate in 2 but should win after Bxf7.

```
7r/1p3Q1p/2q5/3bk3/1Q2p3/2P5/r2P2PP/2KR4 w - - 0 1

1. d4+! exd3 2. Qbf4

```
> 29 votes

# Answer
When normal moves don't seem to work to solve a problem, you have to look for special moves like underpromotion, castling or en passant. The latter is the case in this problem, as 1. d4+ exd3 e.p. (forced) 2. Qbf4# mates.
> 7 votes

---
Tags: checkmate, problems
---


title: How to improve from ~1200?

text:
# Question
Title: How to improve from ~1200?
I am not new to the game of Chess. I have been (casually) playing it for over a decade, and I would like to get better at it.

I know the basic rules of the game very well, I understand basic tactics (forks, pins, skewers, zugzwang), good bishops vs. bad bishops, center advantage, etc, and I believe my core principles are pretty good.

However, I do not have any actual theory memorized, and I believe I miss out on some positions.

I would like to understand the game better and get to 1500 by the end of the year. I am willing to put in time and effort. What resources/books would you recommend?

# Answer
> 34 votes
@Arka Mukherjee, I find most players under 2100 weak tactically, so at 1200, you are certainly weaker than you understand you are. I do not say that to be mean, but just as a very logical person, who has been a reasonably strong player for over 30 years.

At your level, memorizing theory is mostly a waste of time. In 40 years of playing, I cannot tell you how many weaker players I have seen that carry around an arm full of opening books, but they never progress. You do not need to memorize openings when your opponent is not going to play them because he has not memorized them. You need to understand opening pawn structures. Chess Opening Essentials: The Complete Series (Volumes 1 - 4) is a very basic way to start this.

This is, of course, on a different level, but I recently read something about Kramnik training young prodigies, and one of them played an opening he saw a higher-rated GM play, and he imitated the play by rote, but soon went astray. He did not understand, at least on the much higher level he was at. Understanding is the key.

Beyond that, tactics are the most important thing you can do. Most chess games between weak players are decided by who drops the last piece, and these books would help you win more material, and thus, win more games.

I recommend starting with "1001 Brilliant Ways to Checkmate", and then "1001 Winning Chess Sacrifices and Combinations" (21st Century Editions) by Reinfeld.

I recommend doing 50 per day, spending no more than two minutes per move on each problem. In pencil, write down next to the problem how easy you found it on a scale of 1-5 because you will do these books multiple times. That immersion method has worked very well for me. I took a friend, who was about 38 at the time, from 1000 to 1850 on ICC in three months following this method.

# Answer
> 12 votes
Your first task should be to get better at tactics. It's one thing to understand what a pin is and why it works, for example, but it's quite another to be able to spot the circumstances under which it's advantageous for you to use it.

So my first advice to you would be to work out solutions to tactical puzzles found in books or software. There's a series of books from Russia Chess House called "Chess School" (vols 1a, 1b, 2, 3) which set out 500+ tactical puzzles.They start at levels good for 1200 and go on up to 2000+ by the third book. They're not the only ones, but they're the ones I usually use when I'm teaching. If you'd rather use software, the best is CT-Art, which has grown into a series, or the "Chess Tactics for ..." series. Both were originally created by Convekta (the company that makes Chess Assistant) and I've seen them for Windows desktops as well as iPhones/iPads, not sure if they're around for other devices.

But the point is not so much to use those specific tools as to start loading your brain with patterns of how the various tools in your tactical tool box can be used. Learning those patterns well will help you spot them quickly when they show up on your board, and the goal is to learn them so well it takes next to no effort at all to spot the possibility of one existing; the idea will just pop up when you see the position. It's OK to have to spend time calculating to see if the idea actually works, it's spotting the main idea of the combination almost immediately that matters. It might take a while, and the effect might surprise you. I remember spending weeks working through the chapter on pins in the Informant's Encyclopedia Of Chess Middlegames, a few positions every day. The next tournament I was astonished at how many pins were showing up in my games; I suddenly could not only see the pins, but knew which ones I could really make use of and how.

Another thing to do for tactical study is to play over games from some early chess masters, from Morphy to Andersson, to Pillsbury to Colle and Speilmann, and on through players like Alekhine, Bronstein, and Tal. The idea is not to study the games deeply, but play them over like a "chess movie" and just enjoy the fireworks. Each player will drill into you the themes they've employed, whether it's Speilmann's use of the two bishops or Morphy's exploitation of time or Rubinstein's "feel" for the right place to set his pieces before the action begins. Just watching, you'll begin to soak it up.

Spending a lot of time on opening theory at this point is wasteful, but thinking about it a little won't hurt and can help you. The most important thing to remember about the opening is that your main task in it is to reach a playable middlegame, one where your tactical study will pay off. Feel free to experiment with many different openings; just don't go into a deep dive into any of them. When your opponent plays a line you haven't seen, take a few minutes and look it up after the game; don't waste precious skill development time preparing for moves you never see over the board. You have other things to work on. Your prime goal in opening study is to avoid traps (something tactical knowledge will help with) and keep from losing the game in the opening; so long as you're still playing at the end of the opening phase, you're passing the test.

At this point also spend some time on basic endgames, especially pawn endings. Learn the techniques of winning pawn endgames so well that when your tactis win you an extra pawn, you can confidently know you'll win even if all the rest of the pieces disappear. That's quite useful, because if your tactics have won you the exchange, for example, the simplest and easiest way to win is to give back the exchange to win a pawn, and win with the pawn.

If you're looking for a "time budget" I'd say 50% tactics, 30% endgames, and 20% openings for a study plan, and you could easily profit by adding time to tactical study at this point at the expense of opening study. It doesn't matter who comes out of the opening with a better position, after all, if you can outplay them tactically at that point and win the endgame. And as your tactical ability improves, you could take some of the time you used to spend on tactics and spend it on endgames. Only when you've mastered those should you start spending more time on openings.

Look at it this way, any non-fatal mistakes you make in the opening can be fixed in the middlegame, and non-fatal mistakes there can be fixed in the endgame, you can count on this being true so long as you can play those phases better than your opponent. Extensive opening theory knowledge becomes more useful as your opponents get better; at levels below 1800-2000, it's not very necessary. And if you keep experimenting with new openings, by the time you get to the point where you need to spend time in theory, you'll have a better feel for the middlegame positions you like to play, and are good at, so you'll have a better idea of which openings you'll want to study.

# Answer
> 10 votes
at 1200 I strongly believe You are wrong about all your core assumptions about your understandings; or if you really have those strategic/positional understandings you must start to do tactics - at least 1h of puzzle solving per day will make best improvement for 1200 player anyway.

and forget about spending time on theory until you are at least 1800, preferably 2000+ - I personally know multiple GM's who never in their life specifically studied opening theory but their top ELO was 2600+. I also never did and my top ELO was 2400 over the board and 2600 in correspondence chess. Understanding the base principles of game will make you choosing good move in opening in 90+% of time. There are cases when deep tactical analysis overthrow base concepts, you can get caught by variant to get worse position or miss bigger advantage but that can still happen even if you study openings hard - not that big loss here.

# Answer
> 6 votes
1200 on what scale? Elo USCF some inflated online site??

You do not need theory at all. What you need is useful tactics training. And you need endgames. That will help you more than theory. Do one theme at a time and repeat ten-15 times that day. Come back in a couple of days and repeat it. When you know it cold then wait several weeks and try again. Come back regularly but let the time between reviews get longer as your ability to do them easily requires. The goal is to spot the patterns in your games without thinking.

After that focus on pawn structure and ONE opening system as white and one with black.

# Answer
> 1 votes
At the 1200 level, you will find that most games are won or lost tactically. In fact that's true even up to much higher levels. Accordingly, working on tactics should serve to improve your game and raise your rating. There are numerous sources online (ChessTempo, Chess.com, Spark Chess, etc.) that provide interactive tactical problems to do that. Playing regularly should also help improve your "sight" of the board to spot tactical possibilities or thwart opposing ones. It has been pointed out that such possibilities generally arise from a positional advantage, so you should adhere to the standard recommendations for same to reach such positions - quick development of your pieces and early castling, controlling the center, controlling open files, commanding outposts, etc., all of which you indicate you are aware. Recording and analyzing your games is also recommended, preferably with the help of stronger players, as well as playing over well-annotated Master games, say from game collections of the greats. A little end game study wouldn't hurt either since a "won" game is often drawn or even lost there. It may sound like work, and it is, but nothing comes easily in life, or chess, unless you're a rare prodigy like Capablanca or Morphy. As far as books on tactics are concerned, as an octogenarian I'm more familiar with the older ones such as Fred Reinfeld's "1001 Winning Chess Sacrifices and Combinations" and "1001 Brilliant Ways to Checkmate", and Laszlo Polgar's "5334 Problems, Combinations and Games", but tactics never go out of style, and they'll work as well as current books. Jeremy Silman's books on "How to Re-assess Your Chess" should help with theory. Reaching 1500 should be a reasonable goal for you, although not necessarily by the end of the year. Why set a time limit? Just play regularly, take your losses in stride as learning experiences and enjoy the game, and improvement should come in time in the normal course of events.

---
Tags: learning, books
---


# Question
Title: Which book should one read if they want to play like Tigran Petrosian?
According to Wikipedia, the former world champion Tigran Vartanovich Petrosian has "almost impenetrable defensive playing style, which emphasized safety above all else".

Here defensive is by no means passive and emphasizing safety above all else is surely not a bad thing (see Petrosian's accomplishments). Which book would you recommend, if one wishes to play like Petrosian?

# Answer
One of Petrosian's greatest strengths was his prophylactic thinking; i.e., identifying threats before they arise and neutralizing them. A book which discusses this concept would be good. For example, "Recognizing Your Opponent's Resources: Developing Preventive Thinking".

If you want to learn more about Petrosian himself, part 3 of Kasparov's My Great Predecessors series would be good. In this book he goes over the games of Spassky and Petrosian.
> 4 votes

# Answer
Petrosian's Best Games of Chess 1946-63 by P.H. Clarke, published by Bell & Sons is the obvious place to start.
> 3 votes

# Answer
Shektman has a great two-volume set on Petrosian's games, but really, to play like Petrosian you need to get very good at tactics. One of the secrets to his playing style was the way he could sniff out the tactical possibilities inherent in the position and defang them before his opponent could take advantage of them. Daniel Naroditsky wrote a little something about that at https://www.chess.com/article/view/petrosians-tactical-side

Something to play close attention to in his games are the rooks; he was a master of the exchange sacrifice.

Maybe a good book for starters would be Petrosian, Move By Move, by Thomas Engqvist. It takes a look at several of his games and tries to explain every single move.
> 2 votes

---
Tags: books, world-championship, defense
---


title: Checkmate possibility for Black

text:
# Question
Title: Checkmate possibility for Black
In this lichess game, in the given analysis line for move 32, is it possible for Black to win in two moves after 35... Kc7?

```
[FEN "8/R4k2/2p3p1/2N4p/3n4/3P1pPb/PP3P1P/6K1 b - - 0 1"]

1... Ke8 2. Ra8+ Ke7 3. Ra7+ Kd8 4. Ra8+ Kc7

```

---

```
[Title "Anonymous-Anonymous, lichess.org. Rapid Game, 5/12/2020"]
[FEN ""]

 1. d4 g6 2. d5 e5 3. e4 Bc5 4. Nf3 a5 5. Nc3 Ba7 6. Nb5 Ne7 7. Nxe5 Nxd5 8. Qf3 f6 9. Nc4 Nb4 10. Bd3 O-O 11. O-O d6 12. Nxa7 Rxa7 13. e5 dxe5 14. Be3 Nxd3 15. Bxa7 Nc6 16. Qxd3 Qxd3 17. cxd3 Nxa7 18. Nxa5 f5 19. Rac1 c6 20. Rc5 f4 21. Rxe5 f3 22. g3 h5 23. Rfe1 Kf7 24. Re7+ Kf6 25. Re8 Rxe8 26. Rxe8 Bd7 27. Rd8 Ke7 28. Nxb7 Bh3 29. Rg8 Kf7 30. Ra8 Nb5 31. Nc5 Nd4 32. Ra7+ Kf6 33. Ne4+ Ke6 34. Nc3 Kd6 35. Rf7 Ke6 36. Rf4 Ke5 37. Rh4 Bg2 38. h3 g5 39. Re4+ Kd6 40. Rxd4+ Kc5 41. Re4 g4 42. Re5+ Kd4 43. Rxh5 gxh3 44. Nd1 Kxd3 45. Ne3 Ke2 46. Nxg2 hxg2 47. Re5+ Kd3 48. Rc5 Kd2 49. Rxc6 Kd1 50. b4 Ke1 51. b5

```

# Answer
The position after 35 ... Kc7 is a win for Black.

The immediate threat is mate with Ne2+ and Bg2; if 36 Kg1 Bg2+ 37 Kg2 Ne2+, still mate with the same two moves in reverse order -- but not 36 Kg2 Ne2+ 37 Ne6+! and 38 Nf4. If 36 Re8 Ne2+ 37 Rxe2 fxe2 and it's still mate in a move or two with e1Q because White's own Pd3 is in the way of defending with 38 Nd3.

White has a better defense with **36 Ne6+!**, disrupting the mating net by forcing Black to capture with either B or N. Material is then about equal, but after **36 Ne6+! Nxe6!** (not Bxe6 37 h4 or 37 Kf1) the Kg1 is still trapped and the Knight threatens to go back to d4 and thence to e2 for the same mate. After **37 Ra4 g5!** (not yet c5 38 Rh4! dislodging the Bishop, e.g. 38 ... Bg2 39 h3 and the wK escapes to h2) Black's plan is c5, Nd4, and mate. White will have to give up the Exchange (e.g. **38 Rc4 Nd4 39 Rxd4 cxd4** -- even worse is 39 Rxc5+ Kd6) and now White is behind on material, with King still trapped and the d3-pawn about to fall too, so Black should win the endgame in due course.
> 3 votes

# Answer
If the object is to prevent a mate in two, White easily does that by playing Ra7+. But that is not the question, as after ...Kb6 White is still losing.

Black's threatened mate begins with Ne2+, so I'm presuming you want to prevent that mate entirely, not merely postpone it, and I don't see how. Re8 is the only white move that even bears on that square, and even after giving up R for N a checkmate remains on the board via pawn promotion. And while White could give up the N to gain a tempo with Rook by Ne6+, it still only delays the inevitable. I'm not even sure White could avoid losing if the Rook were replaced with a Queen.
> 2 votes

---
Tags: analysis, endgame, checkmate
---


title: How to build a good opening repertoire?

text:
# Question
Title: How to build a good opening repertoire?
I am struggling to build a good opening repertoire. I have tried a few chessable courses. None of them have worked. My opponents counter my opening pretty easily. What is the best way to build a good opening repertoire? My openings for black are the Modern and the Dutch and my opening for white is the London System?

# Answer
Expanding on RemcoGerlich's comment...

Beginners often overestimate the importance of opening theory. If your rating is below around 2000 or even somewhat above) it is perfectly possible to get by with a very rudimentary knowledge of opnenings. It is unlikely that you lose many games because of the opening. All of your mentioned openings tend to go for closed positions and are not full of tactics or traps that you can fall into. It is much more likely that you lose for other reasons than lack of opening repertoire.

Much more important is being good at tactics and having a good positional understanding, knowing the typical plans in certain pawn structures. The first part tactics is easy to train by repetition solving puzzles. The second aspect (positional understanding( is harder and requires time. I recommend to read through annotated games or (nowadays) watch commented games of which you find plenty on chess24, chess.com, youtube, etc.

Once you have a decent understanding of plans and positional play, learning openings will make much more sense because you will understand why a certain move is made and also what to do if your opponent makes a non-standard move that is not in your repertoire.

Most definitely you don't want to learn openings by heart without understanding the ideas behind them.
> 8 votes

---
Tags: opening, learning
---


# Question
Title: Stockfish draw value randomization and "3-fold blindness"
In this commit, a change was made to the way Stockfish scores board positions that are draws due to 3-fold repetition or 50-move limits. Prior to this commit, a drawn position was assigned a score of zero; afterwards, it is randomly assigned a score of +/-1 (that is, a tiny non-zero value). In the commit message, the intended result is explained:

> The effect is that in positions with many 3fold draw lines, different lines are followed at each iteration. This keeps the search much more dynamic, as opposed to being locked to one particular 3fold.
>
> An example of a position where master suffers from 3fold-blindness and this patch solves quickly is the famous TCEC game 53:
>
> FEN: 3r2k1/pr6/1p3q1p/5R2/3P3p/8/5RP1/3Q2K1 b - - 0 51
>
> master doesn't see that this is a lost position (draw eval up to depth 50) as Qf6-e6 d4-d5 (found by patch at depth 23) leads to a loss.

I don't understand what the change actually accomplishes. Why is visiting drawn positions in different orders helpful? What is meant by "3fold blindness"?

For reference, here's the board position mentioned in the message.

```
[FEN "3r2k1/pr6/1p3q1p/5R2/3P3p/8/5RP1/3Q2K1 b - - 0 51"]

```

# Answer
I would first like to acknowledge that this answer is somewhat speculative; this is the first time I've seen this feature in a a chess engine, and I'd be interested to know what other chess programmers think of my answer.

---

Contrary to what is commonly believed, (good) chess engines don't just "search all possible moves" up to a certain depth then pick the best one. If we were limited to this, modern engines would only be ~1600. An incredibly, stupidly important idea in chess programming is that of "reductions." There are many different types, but the basic idea is that computers don't search some lines it doesn't consider promising.

Of course, this is a very double edged sword. On the one hand, you get much deeper and more effective searches, but on the other you are destined to miss something. To give you a taste, consider the following position:

```
[FEN "3n3k/rp4pp/1p5r/pPp1pp2/PpPp1p2/3PpPp1/RN2P1P1/QBNR1BK1 b - - 0 1"]

```

I'm confident a reasonable player can find the simple mate for black (get both rooks on the h file, and mate on h1, after Ne6 to ensure that White cannot break through), but Stockfish 10 can't find it at "**depth 50**". This happens because the mate involves like 7 consecutive quiet moves, which Stockfish doesn't see as significant enough to warrant intensive search. (Another example on Lichess.) When engines miss tactics, most of the time something like this is to blame.

One of the most common forms of this technique are "late move reductions," wherein the computer **selectively** reduces moves found later in the move ordering. (this sorta presupposes you have semi-decent move ordering, but you said you already knew a little of that, so we're skipping it).

---

Next, iterative deepening. Basically, the idea is that if you ask Stockfish to search at depth 25, it will start by searching depth 1, then depth 2, then depth 3,... then depth 25. This seems like a stupid idea at first, but it has various benefits most of which I won't go into. What's relevant here is that the depth 24 search informs decisions about reductions the depth 25 search makes. So if depth 24 says a move isn't too promising, depth 25 is less likely to search it deeply. (this is a **massive** simplification).

---

Ok so what's happening in the commit?

> The effect is that in positions with many 3-fold draw lines, different lines are followed at each iteration. This keeps the search much more dynamic, as opposed to being locked to one particular 3-fold.

Here's how I'm reading this: Before the commit, the computer will be searching the same draws at every iteration. If there are lots of 3-fold lines, it's possible the computer won't search all of them (or at least, all of them deeply). This can lead to "blind spots," where the computer doesn't notice some sideline in a move with a draw score.

Before the commit, each successive iteration would have (roughly) the same blind spots (albeit with more resources to notice the sideline). After the commit, the blind spots are scrambled at each iteration, making it less likely to miss the sideline.

---

As a toy hypothetical example (which shouldn't be taken too literally): say we have two "draw" moves A and B, both of which are way out at the horizon of the search. Because they are so far away, the computer's evaluation of them is very bad (for several reasons, but for the time being we can just think that only a few of A and B's children are searched due to reductions) so it's possible A and B aren't actually draws.

Now for whatever reason (perhaps reductions), let's say the computer has allocated 5 resources to search the "best" draw move and 3 resources for the "second best" draw move at iteration 24, while allocating 6 and 4 respectively at iteration 25.

Let's also say A is a genuine draw, but B has a sideline which isn't, and will be noticed if it is searched with 5 resources.

Before the commit, if A is searched first at iteration 24, it will likely also be searched first at iteration 25 (meaning the sideline slips through), but after the commit, A and B are equally likely to be searched at each iteration, meaning the sideline is more likely to be found at *some* iteration, whereupon the computer will take note and correct.

I don't know if that made any sense whatsoever, but I hope it helps.

---

Again, I'm very open to being corrected here. This is just my reading of the commit.
> 2 votes

# Answer
The general answer is that by scoring these "3-fold" and "50-move" draws with some randomization, the engine will naturally be encouraged to explore different lines of play on successive searches. Moreover, these "draws" won't all be flooded into the Transposition Table (Big table of saved search results) with the same score.

I put "50-move" in quotes for a reason. Due to how positions are stored into the Transposition Table (often without regard for the actual 50-move counter), its possible for a position to "appear" to be a draw, but not actually be. The best example would be the cursed-wins / blessed-losses that occur in the Syzygy Tablebases, which require an extension of the 50-move rule in order to obtain mate without drawing.

For "3-fold" draws, there is a similar reason. I am not absolutely certain of the inner workings of Stockfish, but I believe the following is true for Stockfish (and is certainly true for some others): Often time "2-fold" repetitions are scored as draws. This is to speedup the search greatly (gains elo). I say "often times". Sometimes this is not the case, like when the first occurrence of a given position occurred BEFORE the root of the search. In other words, the the "2-fold" occurs entirely in the search, and has not actually been played in part or in full over the board. Again, this trick of randomization encourages some additional exploration, which helps to avoid rather "unlucky" understandings of a position.
> 2 votes

---
Tags: engines, stockfish, programming
---


# Question
Title: Is this implementation of Killer Move heuristic correct?
I implemented the killer move heuristic based on my understanding, but is it correct?
Inserting a killer move when a non-capture causes a beta cutoff (i is a Move pointer)

```
// Stuff
if(val >= beta){
        // Non capture move that causes a beta cutoff = Killer Move
        if(!GameObj.is_capture(*i, player))
            insert_killer(*i, depth);
        return beta;
    }

```

Actual Insertion By Shifting

```
void insert_killer(Move m, short depth){
for(short i = 0; i < KillerSize - 1; i++)
    // Shift the moves
    KillerMoves[depth][i] = KillerMoves[depth][i + 1];
KillerMoves[depth][KillerSize - 1] = m;
}

```

Storing in move generator

```
vector<Move> non_captures;
vector<Move> captures;
vector<Move> Killers;
// Stuff
if(!this->is_capture(move)){
    if (is_killer(depth, move))
        Killers.push_back(move);
    else
        non_captures.push_back(move);
}
// Stuff

```

Ordering in move generator

```
// Stuff
vector<Move> all_moves;
sort(captures.begin(), captures.end(), comparer);
all_moves.reserve(captures.size() + non_captures.size() + Killers.size());
all_moves.insert(all_moves.end(), captures.begin(), captures.end());
if(!capture_only){
    all_moves.insert(all_moves.end(), Killers.begin(), Killers.end());
    all_moves.insert(all_moves.end(), non_captures.begin(), non_captures.end());
}
return all_moves;

```

# Answer
> 2 votes
This appears fine to me. However, there are some things to note:

1) Its important to be careful that you do not try playing the same move twice. Your "Storing in Move Generator" appears to accomplish this.

2) It is generally a bad idea to save the SAME killer into multiple slots of your table. This reduces to effective size of your Killer Move table, and also makes it possible such that the following occurs: Your table contains {A, B, C, D} for a given depth. Move D is then found to refute 3 different lines of play (Awesome!), now your table contains {D, D, D, D}. If A, B, or C had any value, it is now lost.

3) From personal experience, there is hardly any benefit to having more than two Killer moves for a given depth. In Ethereal, three-moves loses elo over two-moves, and two-moves is almost the same as one-move. I believe Stockfish uses two killers, although my information may be out of date.

---
Tags: engines, programming
---


# Question
Title: How do I promote my pawn when the king blocks it?
I was playing ChessEndGames and ran into this position (white to move):

```
[fen "5k2/8/4PK2/8/8/8/8/8 w - - 0 1"]

```

I can't get my pawn to promote. As soon as I do `e7`, black follows with `Ke8`. If I do `Ke5`, black does `Ke7`. If I do `Kf5`, black does `Ke8`, and if I follow it with `Ke5`, black does `Ke7`.

I am in deep trouble. I don't get it how to promote my pawn.

# Answer
> 23 votes
This position is a draw with White to move. However, the same position would lead you to win if it was black to move (Zugzwang).

The basic theory for you to promote the pawn when the opponent king is having the opposition is you need to have your king in front of your pawn 2 ranks ahead of the pawn, (i.e. if pawn's on e3 King needs to be on e5) (opposition means - being right in front of the king when its his opponent's turn to move, for example- in your position black has gained the opposition with white to move), lets say in the same case, its black to move, that means white has the opposition and after black moves to lets say Ke8, e7 wins you the games as the king now has only 1 square to move that is Kd7, now as it is your turn to move, you play Kf7 and gain the opposition again in front of black king Kd7(sideways), so now black can't play Ke8 and you can promote the pawn and win the game.

---

In this game it's White to move and he gains opposition and put Black King in Zugzwang. (Make sure to read comments for the moves appearing in the box below each game)

```
[Date "????.??.??"]
[Result "*"]
[FEN "8/8/8/4k3/8/8/3KP3/8 w - - 0 1"]

1.Ke3 { Gaining opposition and putting Black king in zugzwang, so black king has to move and give up one of the key squares which is d4, e4 or f4. } ( 1.Kd3 {This is a blunder as now it will just be a draw } Kd5 2.e3 ( 2.e4+ Ke6 3.Kd4 Kd6 4.e5+ Ke7 ) 2...Ke5 3.e4 Ke6 4.Kd4 Kd6 5.e5+ Ke7 6.Kd5 Kd7 7.e6+ Ke8 8.Kd6 ( 8.Ke5 Ke7 9.Kf5 Ke8 10.Kf6 Kf8 11.Ke5 ( 11.Kf5 Ke8 12.Ke5 Ke7 ) 11...Ke7 ) 8...Kd8 9.e7+ Ke8 10.Ke6 ) 1...Kd5 { If Ke6, then white plays Ke4 and gains opposition again. } 2.Kf4 Ke6 ( 2...Kd6 3.Kf5 Kd5 4.e4+ Kd6 5.Kf6 Kd7 6.e5 Ke8 7.Ke6 ) 3.Ke4 Kf6 4.Kd5 Ke7 5.Ke5 Kd7 6.Kf6 Ke8 7.e4 Kf8 ( 7...Kd7 8.e5 Ke8 9.Ke6 Kf8 10.Kd7 ) 8.e5 Ke8 9.Ke6 Kd8 10.Kf7 Kd7 11.e6+ Kd8 12.e7+ Kd7
*

```

---

Here White King is only 1 rank ahead of the pawn and if black can gain the opposition, game will be a draw. It is Black To move and Black gains the opposition and draws.

```
[Date "????.??.??"]
[Result "*"]
[FEN "8/8/8/3k4/8/4K3/4P3/8 b - - 0 1"]

1...Ke5! { Now White has no way to gain back the opposition while being ahead of the pawn. } 2.Kf3 Kf5 3.e4+ Ke5 4.Ke3 Ke6 5.Kf4 Kf6 6.e5+ Ke7 ( 6...Ke6 { Also Playable } 7.Ke4 Ke7 { Both the same. } ) 7.Kf5 Kf7 8.e6+ Ke8 9.Kf6 Kf8 10.e7+ ( 10.Ke5 Ke7 ) 10...Ke8 11.Ke6
*

```

---

But if White is 2 ranks ahead of the pawn, then he can win the game even if black has the opposition as he has to give up the opposition soon as shown below.

```
[Date "????.??.??"]
[Result "*"]
[FEN "8/8/4k3/8/4K3/8/4P3/8 w - - 0 1"]

1.e3 { Now Black has to give up one of the key squares which is d5, e5 or f5. } 1...Kd6 2.Kf5 { And after this White wins as shown in above example. }
*

```

# Answer
> 7 votes
There is no way to promote the pawn here. The position is drawn if it is white to move. With black to move it would be won. You may want to read up on key squares and the opposition to get a better understanding of such situations in general.

# Answer
> 5 votes
In your diagram, White wins if the Black king is on e8, with White to move. Then the winning move is e7, and the king has to move "out of the way" to d7, you play Kf7, and the pawn queens.

But if it is your move in the diagram, it's only a draw, because Black has what is called the "opposition," meaning that you have to move out of the way when the kings are facing each other on f file. If it were Black to move, you'd have the opposition, and win.

In king and pawn endings, it's often true that "The opposition is worth a pawn." This is a case in point.

# Answer
> 3 votes
Black has forced an opposition against white. There is no way to win from here unless the opponent lacks the end game skills of attaining opposition. You can test his endgame skills by moving the king and check if he moves to the current position i.e. `Kf8` when you are one square way from `Kf6`.

# Answer
> 0 votes
This seems like a draw to me. This is because the king blocks and it is either something captures the pawn or it is stalemate. Or the white could win if black plays a wrong move.

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


# Question
Title: Most pieces involved in checkmate in actual game?
I recall seeing a number of chess games where a lot of pieces are involved in the final checkmate, and was curious to know what is the maximum number of pieces of one player A that have been involved in a checkmate of the other player B, where a piece is said to be involved if and only if removing it either causes B's king to be no longer in check or causes one of the squares around B's king to be no longer attacked by A's pieces. It is easy to construct a reachable position where 9 pieces are involved, and to prove that no more than 9 pieces are involved. It is also possible for all 6 types of pieces to be involved. For example:

```
[White "Checkmate"]
[Black "9 pieces involved"]
[FEN "6B1/7K/2N5/5kP1/2R1P2P/8/6N1/3Q4 w - - 0 1"]

```

But are there any actual competitive games that ended with such a checkmate (i.e. using 9 pieces)? If not, what is the maximum number ever used in a competitive game? Among these games, what is the maximum number of types of pieces used? I exclude non-competitive games merely to avoid contrived games.

Note: As John Coleman pointed out in the comments, this notion of "involved" is more like "critically involved" because it is possible that a checking piece is covering another piece that would also provide check if the first was removed, or that a piece next to the checkmated king is protected by more than one piece. One could consider a variant notion of "loosely involved" defined as follows: A piece X of A is loosely involved in a checkmate of B if and only if we can remove some pieces of A that attack B's king or a square next to B's king such that it is still a checkmate and X is (critically) involved. I think this should cover such cases, so I am fine with including examples that use this looser definition of "involved".

# Answer
> 5 votes
It took a while, but I found via youtube an old well-known game with a king hunt ending in checkmate with 5 involved pieces!

```
[Title "Josef Matschego − Ernst Falkbeer , Vienna (1853)"]
[FEN ""]
[startply "50"]

1. e4 e5 2. f4 exf4 3. Nf3 g5 4. h4 g4 5. Ne5 Nf6 6. Nc3 d6 7. Nc4 Be7
8. d4 Nh5 9. Be2 Bh4 10. Kd2 Qg5 11. Kd3 Nc6 12. a3 Bf2 13. Nd5 Bd4
14. Nc7 Kd8 15. Nd5 f5 16. Nd6 fxe4 17. Kc4 Qd5 18. Kd5 Nf6 19. Kc4 Be6
20. Kb5 a6 21. Ka4 b5 22. Nb5 axb5 23. Kb5 Ra5 24. Kc6 Bd5 25. Kd6 Ne8#

```

Interestingly, from move 17 onwards it is a mate in 9, and the only way to achieve that is via sacrificing the queen first!

# Answer
> 9 votes
After going through a list of games with king hunts, I found game at last in which 6 pieces are involved in the mate!

```
[Title "Alexander Alekhine-NN, Simul 34b, Moedling Austria, 3/24/1936"]
[FEN ""]
[startply "33"]

1. e4 e5 2. d4 f6 3. dxe5 fxe5 4. Qh5+ Ke7 5. Qxe5+ Kf7 6. Bc4+ d5 7. Bxd5+ Kg6 8. Qg3+ Kh5 9. Bf7+ g6 10. h3 Qf6 11. Nf3 Be7 12. Qg4+ Bxg4 13. hxg4+ Kxg4 14. Nh2+ Kh4 15. Nf1+ Kg4 16. Be6+ Qxe6 17. f3#

```

The Bc1 prevents the Black king from moving to f4 and g5, the e4 pawn covers f5, the f3 pawn is giving mate, the Nf1 covers g3, the g2 pawn protects the mating piece and covers h3, and the Rh1 covers the h3, h4, and h5 squares.

---

Upon seeing this question, I remembered entry #355 of Tim Krabbe’s Chess Diary, which gives some examples of checkmates involving all four minor pieces. The best and simplest example is this game.

```
[Title "Vasily Borisovich Malinin-Viktor Savinov, Leningrad Russia, 1988"]
[FEN ""]
[startply "71"]

1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6 5. bxa6 Bxa6 6. Nc3 d6 7. Nf3 g6 8. g3 Bg7 9. h4 O-O 10. h5 Nbd7 11. hxg6 hxg6 12. Bh3 Re8 13.  Qc2 Rb8 14. Be3 Nxd5 15. Qxg6 fxg6 16. Be6+ Kf8 17. Nxd5 Rxb2 18. Ng5 Nf6 19. Nf4 Qa5+ 20. Kf1 Bxe2+ 21. Kg1 Reb8 22. Bf7 Rb1+ 23. Kh2 Ng4+ 24. Kh3 Rxh1+ 25. Rxh1 Nxf2+ 26. Bxf2 Bg4+ 27. Kxg4 Rb4 28. Kf3 Qa3+ 29. Be3 Qa8+ 30. Bd5 Qa5 31. Nfe6+ Kg8 32. Nc7+ e6 33. Bxe6+ Kf8 34. Nh7+ Ke7 35. Bg5+ Bf6 36. Bxf6#

```

This is easily deduced to be a pure mate, thus raising the known record to four pieces.

Also, to user @John Coleman from the comments, here’s a king hunt, with four pieces, for you. :-)

```
[Title "Roland Schmaltz-Ronen Har-Zvi, Internet Chess Club, 3/7/2001"]
[FEN ""]
[startply "48"]

1. e4 Nc6 2. Nc3 e5 3. g3 Bc5 4. Bg2 Nf6 5. Nge2 d6 6. h3 Bb6 7. O-O O-O 8. Kh2 Re8 9. f4 exf4 10. gxf4 Ng4+ 11. Kg3 Nf2 12. Rxf2 Qh4+ 13. Kxh4 Bxf2+ 14. Ng3 Re6 15. Kg4 Nd4 16. f5 Rg6+ 17. Kf4 Rxg3 18. Qf1 g5+ 19. fxg6 Ne6+ 20. Kf5 Ng7+ 21. Kf6 Rxg6+ 22. Ke7 Re6+ 23. Kd8 Bb6 24. Nd5 Re8#

```

---
Tags: checkmate, records
---


# Question
Title: What would a playable chess variant with a complexity comparable to Go look like?
What would a playable chess variant with a complexity comparable to Go look like?

Simply increasing the board size is a very direct way to increase the complexity of the game, but this comes at the cost of losing playability. No human would be interested in playing chess on a 100x100 board unless the rules were dramatically different.

# Answer
Actually it is not really correct to say that "simply increasing the board size \[...\] comes at the cost of losing playability". The complexity of Go on a board of the same size as chess (i.e. 8×8) would be not high at all, in fact less than chess according to my intuition. But it is true that there is some reason why we humans have a vague feeling that increasing the size of the Go board is not what gives Go its intrinsic complexity, whereas increasing the size of a chess board (say duplicating the pieces and putting them on two sides of a 16×16 board) makes it feel less playable. Based on a mathematical view, it seems to me that the main reason is the difference in the nature of pieces. In chess, many pieces can move from one end of the board to the other. In Go on the other hand, each piece has a fixed location and has a semi-local effect, in the sense that it can exert an effect on another location on the board only if it is in some unbroken chain of pieces that reaches over there. Also, the objective function is a global and fine-grained one in Go (i.e. territory), but a very local and coarse-grained one in chess (i.e. checkmate or stalemate of opponent king). Together, these two factors make Go scalable to large boards without losing playability (except for taking longer), unlike chess.

As you noted, simply increasing the branching factor is not desirable, because otherwise all we would have to do is to increase the board size and number of pieces! To increase the complexity but retain human playability, in a fully scalable manner, one can try to make the objective global and fine-grained, or make the pieces have more localized effects than in ordinary chess, or both. Here are some ideas:

1. **Fine-grained objective:** Remove check/checkmate/stalemate/castling, allow the king to get captured, and add an extra kind of move, to *ascend* any of your pieces that is at the final rank. Passing is allowed whenever there is no valid move. The goal is simply to ascend more pieces than your opponent.
2. **Semi-local effect:** Restrict the movement of pieces; each piece requires half a unit of *energy* per king step from its original location (e.g. moving a knight always requires one unit), and capturing an opponent piece requires 1 extra unit of energy, and each player has 2 units of energy per turn, except that White has only 1 unit on the first turn. For instance, on your turn (except for the first turn) you can push two pawns one step each and move a king twice, or you can move a queen one step (0.5 units) and use a pawn to capture an opponent piece (1.5 units).

These two ideas can be used separately or together, and they can clearly be tweaked in innumerable ways to smoothen or sharpen the game play. For example:

* **Smoother (1):** Break ties in number of ascended pieces by comparing how many moves were taken to ascend the last ascended piece. A tie is still possible if both players make the final ascension move at the same time.
* **Sharper (1):** Narrow the focus by changing the goal to count only the number of ascended pawns, while other pieces cannot be ascended.
* **Smoother (2):** Increase the (square) board size by a factor of k and the number of pieces by a factor of m and simultaneously increase the number of units of energy available per turn by a factor of k×m. It is obvious that this is just making the army and the board more continuous, and the game mechanics retain the same flavour as the original (2). But this will greatly multiply the branching factor (more than exponential in k×m). Setting (k,m) = (2,2) should make for a nice long strategy-heavy war on the board.
* **Sharper (2):** Make the pieces have more varied distance limit per energy usage. Doing so will make the strategy sharper because the stronger pieces (like the queen in the original chess) can maneuver more easily to where they are needed, but usually are best used as supporting pieces except when they can capture and get away.
> 2 votes

# Answer
Besides increasing the board size, there are a few other mechanisms how you can increase the branching factor:

Especially the latter two mechanisms can lead to a massive increase in branching factor, and the two games mentioned also were designed exactly for the purpose of being computationally complex.
> 1 votes

# Answer
The essential difficulty in Go does not reside in anything that can be described as complexity. The rules are as simple as they possibly could be. The difficulty comes from the scoring system. If you are you are losing the struggle for control in some sector of the board, you may be well-advised not to defend it, because that may only result in more of your stones eventually being surrounded. And if you abandon that sector only when it has become obvious that you should, it will probably be too late. Therefore you must abandon calculation in favor of intuition. That is why it took so long for computers to get good at Go. And we still dont understand how they did it.
> 0 votes

---
Tags: chess-variants, game-complexity
---


title: Take my Queen, Please

text:
# Question
Title: Take my Queen, Please
I find the conclusion of the following game very aesthetic. White could have won by taking in `d3` or in `f5`, but played the cute `Qe5`, which

* sacrifices the Queen,
* puts Queens side-by-side (in the middle of the board but not necessarily),
* and is the best move (that mates in five).

Do you know any other game with the same pattern?

```
[fen "5r1k/p1R4p/8/5q2/4Q3/3r4/P5PP/5RK1 w - - 0 1"]
[title "Jozsef Horvath vs Gerhard Adensamer, Dornbirn op (1990)"]

1. Qe5+!! 1-0

```

# Answer
Adams - Torre comes to mind. It does not fully answer your requirements - some sacs are not side by side, some are not in the middle of the board - but still...

```
[fen "2r1r1k1/1p1q1ppp/3p1b2/p2P4/3Q4/5N2/PP2RPPP/4R1K1 w - - 1 0"]

1. Qg4 Qb5
2. Qc4 Qd7
3. Qc7 Qb5
4. a4 Qa4
5. Re4 Qb5
6. Qb7 1-0

```
> 6 votes

# Answer
Another great game to see is the final move of this 1975 game by grandmaster Boris Katalymov.

```
[Title "Boris Katalymov-Mikhail Kolpakov, Riga, 1975"]
[FEN ""]
[startply "65"]

1. d4 d5 2. c4 e6 3. Nc3 Nf6 4. Bg5 Nbd7 5. e3 c6 6. cxd5 exd5 7. Qc2 Be7 8. Bd3 Nh5 9. h4 Bxg5 10. hxg5 Qxg5 11. Nh3 Qe7 12. g4 Nhf6 13. g5 Nh5 14. Be2 g6 15. Bxh5 gxh5 16. O-O-O Nb6 17. Nf4 Bg4 18. Rdg1 O-O-O 19. Nxh5 Bxh5 20. Rxh5 f6 21. Rgh1 fxg5 22. Rxh7 Rxh7 23. Rxh7 Qf6 24. a4 Kb8 25. a5 Nc4 26. a6 bxa6 27. Na4 Nb6 28. Nc5 Ka8 29. Nxa6 Rd7 30. Nc5 Rd8 31. b3 Rf8 32. Qd3 Rf7 33. Qg6

```
> 3 votes

---
Tags: patterns
---


# Question
Title: Queen against rook-drawn and won endgames
I played a game in which I had a queen against a rook but it seemed that my opponent’s king could protect his rook, and there were no pawns on the board. In the end, I drew the game. Are such games be drawn easily and won only in certain positions?

# Answer
> 5 votes
Quoting https://en.wikipedia.org/wiki/Pawnless\_chess\_endgame#Queen\_versus\_rook

> A queen wins against a lone rook, unless there is an immediate draw by stalemate or due to perpetual check, ... (or if the rook or king can immediately capture the queen)

The same article also says

> With perfect play, in the worst winning position, the queen can win the rook or checkmate within 31 moves

In practice if the defending side knows what they are doing it can be quite difficult to win, especially if, as you say, the king and rook remain in contact. A key position to know is the Philidor position, where white can force the king and rook to be separated, and then the rook can be won by a fork. See https://en.wikipedia.org/wiki/Philidor\_position#Queen\_versus\_rook

---
Tags: endgame, queens, rooks
---


title: What are some good chess calendars?

text:
# Question
Title: What are some good chess calendars?
I am having a hard time keeping up with recent tournaments. Are there any good online calendars?

# Answer
Here's a link to the fide calendar: https://www.fide.com/calendar

Also, this link includes the tournaments which will feature some of the top super GMs (e.g., the Olympiad, Sinquefield Cup, Altibox Norway Chess): https://chess24.com/en/read/news/2020-chess-calendar
> 3 votes

---
Tags: tournament
---


title: Help needed to find a Swedish opening

text:
# Question
Title: Help needed to find a Swedish opening
It appears that openings are named after almost any country or city in the world. Spanish opening, Italian game, French defense, Hungarian gambit, London system and so on.

Because I am from Sweden I want to learn and play an opening related to Sweden. But to my surprise and dismay I haven't found a single one named after a Swedish location or Swedish chess player (Scandinavian Defense doesn't count because it is for the whole of Scandinavia).

Can you help me find one? The more closely related to Sweden the better.

# Answer
> 6 votes
Stockholm variation of the Grunfeld

```
[FEN ""]

1.d4 Nf6 2.c4 g6 3.Nc3 d5 4.Bg5

```

With immediate threat of Bxf6 and wins the d5 pawn

# Answer
> 9 votes
The Swedish Variation of the Tarrasch Defense is the move 6...c4 in the line below. The name is also used for the same plan in slightly different positions with the same pawn structure.

```
[FEN ""]

1.d4 d5 2.c4 e6 3.Nc3 c5 {Tarrasch Defense} 4.cxd5 exd5 5.Nf3 Nc6 6.g3 c4 {Swedish Variation}

```

Its ECO code is D33. Black tries to capitalize on his queenside majority, while White is going to play e2-e4. I think theory considers the line dubious right now.

There is also the Göteborg variation in the Najdorf Sicilian, famous for its origin story. In 1955, one of the Interzonal tournaments was held in Göteborg, and in round 14 it happened that three Argentinian grandmasters (Panno, Pilnik and Najdorf) had black against three Soviet grandmasters (Geller, Spassky and Keres). All three reached the position below with the new move 9...g5 that the Argentinians prepared beforehand, and all three Soviet players reacted with the same piece sacrifice 11.Nxe6 and won.

```
[FEN ""]

1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Bg5 e6 7.f4 Be7 8.Qf3 h6 9.Bh4 g5 {Göteborg Variation} 10.fxg5 Nfd7 11.Nxe6 fxe6 12.Qh5+ Kf8 13.Bb5

```

I think it's considered drawish these days.

# Answer
> 3 votes
> (Scandinavian Defense doesn't count because it is for the whole of Scandinavia)

However, the Scandinavian Defense inherited its name from analysis by Swedish masters in the late 19th century who showed it is playable for Black.

> The name originated from its adoption by Ludvig and Gustav Collijn, two Swedish brothers who played in the late 19th and early 20th centuries. In the 1897 Nordic Championship, they played the opening many times, each time meeting 2.exd5 Qxd5 3.Nc3 with 3...Qd8, which is a rarely played variation these days. (Source: chess.com)

Ludvig Collijn (Nov-20-1878 – Oct-04-1939 in Stockholm), was a chess author and chairman of the Swedish Chess Federation from 1917 to 1939. He played this opening with success.

Gustaf Collijn (Nov-11-1880 - Nov-06-1968 Sweden) was a younger brother of chess patron Ludvig Collijn. Author, theatre director, and his whole life a chess enthusiast. A celebrity at every major chess event in Sweden.

In 1896 the brothers authored their "Textbook of Chess", Lärobok i Schack.

```
[FEN ""]

1.e4 d5

```

---
Tags: opening, terminology
---


# Question
Title: What is the rationale behind Black playing e6 in so many openings?
I am new to this stack exchange, so apologies if this question doesn't fit here.

Though I have advanced through the game, and now have a somewhat respectable rapid rating of 1550, I have always found some chess openings to be a source of confusion. At present, I play the Slav (proper) against 1 d4, and the Caro-Kann against 1 e4. Many other respected defences don't make sense to me. For example, the French defense has a similar idea to the Caro-Kann in that Black is trying to counter-attack in the centre rather than directly preventing White from playing 2 d4. However, the 'problem child' of the French defense has always been the light-squared bishop. Granted, 1... e6 allows Black to develop the dark-squared bishop on the second move, but this seems to be outweighed by the fact that the problem with the light-squared bishop can persist for a considerable portion of the game. And yet, 1... e6 is more popular than 1... c6, and is at least as theoretically sound. Why is this? The same could be said of the Semi-Slav, which again is more popular than the Slav defense. These moves never seem to be explained by chess authors, and yet they seem to violate opening principles.

# Answer
In the **French Defense**, the modest pawn advance in e6 simply plans to challenge the e4-pawn by d5, without having to recapture with the Queen after a possible capture in d5. The idea is thus similar to the Caro-Kann. The differences are that the Caro-Kann takes away the best square for the b8-Knight, while the French blocks the natural diagonal for developing the c8-bishop. So there is a trade-off but both openings are safe and solid methods against 1.e4.

The idea of e6 in the **Semi-Slav** is also to reinforce the control in d5 and take back with a pawn if White plays cxd5. It's true that the c8-bishop is blocked but Black can solve this by either taking in c4, followed by b5 and Bb7, or by playing b6.
> 9 votes

---
Tags: opening, french-defense, slav-defense, semi-slav
---


title: Knight and King vs Queen and King

text:
# Question
Title: Knight and King vs Queen and King
Can the knight and king in anyway mate a queen and knight?

I was recently playing a game which I lost. The player with the king and queen was playing suboptimally. On the last move I captured a pawn with the queen since I was low on time.

# Answer
> 4 votes
No. The problem is that the queen covers too many squares.

Consider this (illegal) checkmate position with king and 2 knights vs king and queen:

```
[fen "kq6/2N5/KN6/8/8/8/8/8 w - - 0 1"]

```

If you remove either knight then the queen can take the other one.

# Answer
> 0 votes
As far as I know, regardless of the opponent's skill or number of pawns/pieces, it is impossible to Checkmate using only a knight and a king, since the knight can't cover enough squares to completely block the opponent's king.

Hope this helps.

---
Tags: endgame, checkmate, knight-endgame
---


# Question
Title: Theoretically, why is 4. Bd3 NOT one of the best candidates in Caro-Kann?
I seem to find 4. Bd3 to be one of the best choices in Caro-Kann.

```
[FEN ""]

1. e4 c6 2. d4 d5 3. e5 Bf5 4. Bd3

```

My reasoning:

1. White's light bishop can only develop to Be2 or Bd3. Be2 seems passive.
2. In Caro-Kann, Black gives up the center initially to attack it later (say by c6-c5 or other means), thus losing tempo. One of the reasons given is that Black gets the advantage of its light bishop being outside the pawn chain. By immediately challenging it, White seems to attack Black's advantage.
3. At move 4, Black's most active piece is its light bishop. Immediate 4. Bd3 either forces exchange thus bringing Black to square one in development; or it gets Black to lose another tempo with Bf5-Bg6.
4. At 4. Bf3, Black doesn't have the good option of Ne7-Nxf5, which becomes a possibility if White plays Bf3 later.

But I have never seen 4. Bd3 played in titled games.

Can the experts here help me qualitatively understand what is wrong with my reasoning?

# Answer
This is a great example for explaining the concept of the **bad bishop**.

In the center, we see an example of a **pawn chain**. White has pawns on d4 and e5, and black c6, d5 and (soon) e6. These are pretty immobile (until either side plays some pawn break). White's pawns are on dark squares, black's on white squares.

As a result, black's white squared bishop is called a "bad bishop", because it is blocked by its own pawns that are themselves blocked. White's white squared bishop is similarly called a "good bishop" -- it isn't blocked by his own pawns, can help with pawn breaks at the right moment, et cetera.

Why is it even relevant to mention that this variation manages to bring black's white squared bishop outside of the chain? Because being "inside" or "outside" the pawn chain is only relevant for bad bishops. Black's f8 bishop doesn't care about such things. The French defense is a great defense except for things such as leaving its bad bishop on c8.

White also has a bad bishop, the black squared one on c1. But as white has more **space** (d4 and e5 vs d5 and e6) and the pawn chain is **pointed in the direction the Bc1 moves** it is less of a problem, from c1 it will continue to influence far-away squares such as g5. Black's bishop on c8 is just locked in. A way to deal with having less space is to **exchange pieces** so the lack of space isn't felt as much.

Note that outside the pawn chain, it's **still** a bad bishop -- there are only a few squares the bishop can safely go to from f5, there is a danger that it will be attacked and chased by pawns. But at least it has more influence there than on c8.

So what would be even **better** for black's bishop than to merely be outside of the blocked chain? Why, to be **exchanged for white's good bishop**, of course. Without any further concessions, even.

After **4.Bd3 Bxd3 5.Qxd3 e6**, black's opening is a complete success. No bad bishop, white no good bishop, less space but already a piece exchanged. Black has no problems whatsoever.

**All that said,** chess is an equal game anyway. If white could get even a tiny concession out of black, this might still be a useful idea. **4.h4** is a theoretical line (white threatens to chase the bishop with g4, f3, h5) and then if **4...h5**, **5.Bd3** is a main move (the other is **5.c4**). The difference with what has gone before is that g5 has now become a nice square for white's own bad bishop, and that is enough of a difference.

```
[FEN ""]

1.e4 c6 2.d4 d5 3.e5 Bf5 4.h4 h5 5.Bd3 Bxd3 6.Qxd3 e6 7.Bg5 Qb6 8.Nd2

```

Is an exciting line that scores well for white.
> 10 votes

# Answer
The line usually quoted is 4.Bd3 Bxd3 5.Qxd3 Qa5+ 6. Bd2 Qa6! If White now exchanges Queens or allows the Queens to be exchanged he already has a poor endgame structure with a bad dark-square Bishop. Otherwise he will have difficulty Castling. Certainly White is not lost, but he has given away his first-move advantage.

```
[FEN ""]

1. e4 c6 2. d4 d5 3. e5 Bf5 4. Bd3 Bxd3 5. Qxd3 Qa5+ 6. Bd2 Qa6!

```
> 14 votes

# Answer
> But I have never seen 4. Bd3 played in titled games.

The reason could be that Black **gets a superior version of the French Defense**. In the French, Black blocks the natural diagonal of the c8-bishop and then struggles to solve this issue. They lose a lot of tempi to exchange the bad c8-bishop via b6, and Ba6. Here Black immediately trades the light-squared bishop and plays e6.

---

Note: Black's light-squared bishop may become **a target outside the pawn chain** that White can exploit instead of exchanging the bishop.

* While this isn't a big problem most of the time, it gives white a target on the Kingside to accelerate a pawn storm in some instances.
* More problematic could be that White may target Black's light-squared bishop by `Nh4` or `Nd4`.

Two examples from GM Shirov pratice, the great specialist of Be2 in the Caro-Kann advance variation. I recommend studying his games.

```
 [FEN ""]
 [title "Shirov, Alexei (2685) vs. Ehlvest, Jaan (2524), Vladimir Petrov Mem 2016"]

 1.e4 c6 2.d4 d5 3.e5 Bf5 4.Nf3 (4.Bd3 Bxd3! 5.Qd3 e6) e6 5.Be2 Ne7 6.O-O Nd7 7.Nh4 Be4 8.Nd2 c5 9.Nxe4 dxe4 10.g3 Rc8 11.c3 cxd4 12.Qxd4 Nc5 13.Bg5 Qc7 14.Bb5+ Nc6 15.Rad1 h6 16.Bxc6+ bxc6 17.Be3 Be7 18.b4 Na4 19.Rc1 Bxh4 20.gxh4 c5 21.Qxe4 O-O 22.b5 c4 23.Kh1 f5 24.exf6 Rxf6 25.Rg1 Nc5 26.Qxc4 Qb7+ 27.Rg2 Ne4 28.Qd4 e5 29.Qxa7 1-0

```

---

```
 [FEN ""]
 [title "Shirov, Alexei 2630) -  Moehn, Hans (2368), Bundesliga 2017-18"]

 1.e4 c6 2.d4 d5 3.e5 Bf5 4.Nf3 e6 5.Be2 c5 6.Be3 cxd4 7.Nxd4 Ne7 8.O-O Nbc6 9.Bb5 a6 10.Bxc6+ Nxc6 11.Nxf5 exf5 12.c3 Be7 13.Nd2 O-O 14.Nf3 Qd7 15.Bb6 Qe6 16.Re1 Bd8 17.Bc5 Re8 18.Qb3 Be7 19.Bb6 Bd8 20.Bxd8 Rexd8 21.Rad1 h6 22.h4 Rd7 23.Qa4 Rad8 24.h5 Kh7 25.Qf4 Rc8 26.Rd3 Rcd8 27.a4 Kg8 28.a5 Kh7 29.Nd4 Nxd4 30.cxd4 Rc8 31.Rb3 Rc6 32.Rc1 f6 33.Re1 Rf7 34.Rbe3 fxe5 35.Rxe5 Qd7 36.Qf3 Rd6 37.Re8 Qc6 38.Qg3 Qd7 39.Ra8 Re7 40.Rc1 Rc6 41.Rxc6 Qxc6 42.Rd8 Re4 43.Kh2 Qf6 44.Rxd5 Rh4+ 45.Kg1 Rxh5 46.Rd6 f4 47.Qd3+ Qf5 48.Qxf5+ Rxf5 49.d5 Rf7 50.Kh2 Rc7 51.b4 Rc2 52.f3 Rd2 53.Rd7 Rd4 54.Rxb7 Rxd5 55.Rb6 Rd4 56.Kh3 g5 57.Kg4 Rd2 58.Kh5 Rxg2 59.Rxh6+ Kg7 60.Rxa6 Rg3 61.Rg6+ Kf7 62.Rxg5 Kf6 63.Rb5 Rxf3 64.Kg4 Rf1 65.a6 f3 66.Ra5 1-0

```
> 11 votes

---
Tags: opening, caro-kann, bishops, bad-bishop, exchange
---


# Question
Title: Online tools for scheduling teams round-robin events
A solution would allow the creation of pairings, the entering of team results, the viewing of a team ranking table, and ideally allow the listing of an individual ranking table as well.

The best I've found so far is https://tournamentscheduler.net/

However, it seems to have the following limitations:

* It has no respect for colors (so that e.g. it will make Team 1 White in every round)
* It refuses to accept non-integer round results (so you can't say that one team defeated the other 3.5-0.5. You would need to either use match wins as your criterion or else multiply the actual score by 2.

It's also limited in the sense that you can't enter individual results.

# Answer
> 3 votes
What you are really looking for is a pairing program which will perform team round-robin pairing, allow you to enter results and display the results online.

There are two obvious candidates, one expensive and deluxe, and one cheap (free on Linux) which requires a bit more work on your part.

The expensive option is Swiss Manager. This does everything you could want and more but it costs 150 euros for the full version and 75 euros for the light version (limit 60 players / 11 rounds). This includes a website (chess-results.com) where your tournaments can be viewed.

The cheap / free option is Vega. It is free on Linux. On Windows and MacOS it is free for up to 30 players (individual tournament) and 8 teams (team tournament). I paid 50 euros for the full Windows version a few years ago.

Something which is new, which I see for the first time (new since the end of 2019), is that now it also has its own website like Swiss Manager. This is https://www.vegaresult.com/vr/. If you have up to 8 teams or you would run it on Linux then this looks like a very good free solution. Previous versions would generate the HTML for you to copy and paste into your own website. This could still be very useful for more tech-orientated clubs / administrators.

---
Tags: tournament-directors
---


# Question
Title: What were Fischer's 179 demands for a World Championship rematch?
According to this video (at 4:25), Bobby Fischer made 179 demands for a rematch for a World Championship, after he won the title. What were those 179 demands?

# Answer
If it was only about the 1975 match, It could have been a mistake by the video editor. As far as many sources from the web, there were only 3.

1. Not counting the draws, first to win 10 games wins the Championship.
2. If the result is 9-9, then the title goes to Fischer but the prize money is split equally.
3. There will be an unlimited number of games.

The first one was accepted and the other two were rejected by FIDE delegates. Hence the match was forfeited and the champion title was given to Anatoly Karpov, his challenger.

As far as Fischer being concerned who was very demanding in character and liked to impose his own rules, the number 179 could have been total demands throughout his career.

Some other sources mention that he only asked for two rules. You can read the digital version of the newspaper article here: NYTimes

And there is one another source that mentions as per the video. It is the Independent article. I feel that the video editor got the directions from here. Because 179 demands seem very unlikely. If it were true, it is not a World Championship match but some sort of dictatorship.
> 12 votes

---
Tags: history, world-championship, fischer
---