# Question
Title: Is it possible to fully analyse, at least some openings of chess?
While, I'm fully aware that the number of chess moves exceeds the number of atoms in the universe greatly, and so solving it is a problem that falls in NP, I was wondering if certain variations of it can be solved.

I know that chess itself can't be solved.\* But, is it possible to solve at least a few openings ? What I mean is, is it possible for computers to definitely say "For this variation of the Sicilian Defense, White is winning." or "For this variation of the Queen's Gambit, Black is winning." Are there special cases where it is possible to say exactly which side is winning after 7-8 moves? (\* - Strictly speaking, it has not been proven that chess cannot be solved. It cannot be solved by a brute force search of the game-tree, because such a graph is too large. But not all algorithms have been excluded in their ability to solve chess).

# Answer
> 7 votes
The moment we knew that a variation would be winning for either White or Black, the other side would never go for that variation. E.g. after 1. g4 e5, White will never play 2. f3 because we know that variation is winning for Black.

But there are some openings which have been analyzed to a draw by repetition of moves, even before the computer era, e.g. the Greco variation of the main line (Giuoco Piano) of the Italian game:

```
[FEN ""]
1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4 exd4 6. cxd4 Bb4+ 7. Nc3 Nxe4 8. O-O Bxc3 9. d5 Bf6 10. Re1 Ne7 11. Rxe4 d6 12. Bg5 Bxg5 13. Nxg5 O-O 14. Nxh7 Kxh7 15. Qh5+ Kg8 16. Rh4 f5 17. Qh7+ Kf7 18. Rh6 Rg8 19. Re1 Qf8 20. Bb5 Rh8 21. Qxh8 gxh6 22. Qh7+ Kf6 23. Rxe7 Qxe7 24. Qxh6+ Kf7 25. Qh7+

```

Almost all deviations after move 8 or so have been proven either to draw as well, or to lead to a worse position.

# Answer
> 3 votes
There are algorithms/chess engines that can heuristically evaluate a position and provide a score which can be proxied for who is winning.

Completely analyzing an opening would require an engine to follow all paths or at least all reasonable paths (heuristically determined). This is computationally very time-intensive and we are very far from compute power that can do that for us.

# Answer
> 0 votes
It is impossible. There are over 9 million possible positions after the first 3 moves, let alone the whole game! If a computer was to analyse all the positions, then it would

1. Crash
2. Prove that Chess cannot be solved.

Even if we used a quantum computer, which calculates in increasing powers of 2, then we will still have a problem since the number of possible positions will be, I estimate 2^10^100.

So, we can't analyse openings in chess completely.

# Answer
> 0 votes
I must say at a high level for example in the Grünfeld Indian there is a lot to be memorized, and possible to be memorized. People have considerable trouble against a stable player like MVL employing it. A lot of lines are forced and have an outcome.

Still, it will probably take some time before all life is out of the opening. Yet, the main lines have dried out as interesting terrain.

---
Tags: game-complexity
---


# Question
Title: Position from the Dutch Defence / Blackmar-Diemer gambit
In the Dutch Defence, the following gambit isn't very popular anymore.

```
[FEN ""]
1. d4 f5 2. Nc3 d5 3. e4 dxe4 (3... fxe4 4. Qh5+)

```

The same position can arise from the Blackmar-Diemer gambit if black plays the rare `3... f5`.

```
[FEN ""]
1. d4 d5 2. e4 dxe4 3. Nc3 f5

```

Scheerer, on pages 62-68 of his book *the Blackmar-Diemer gambit*, analyses `4.Bf4` and seems to like white's compensation.

What is the true evaluation of the position?

If it's good for white, why isn't the `3.e4` gambit against the Dutch Defence more popular?

If it's good for black, why isn't `3... f5` played more often to counter the Blackmar-Diemer gambit?

# Answer
You raise a very interesting point - you're absolutely correct in saying that `3...f5` is not a common response to the Blackmar-Diemer gambit. However, the gambit can be reached in another way where Black doesn't have the option of playing this move:

```
[FEN ""]
1. d4 d5 2. Nc3 Nf6 3. e4 dxe4 4. f3

```

In the Dutch, Black can sidestep White by playing this move:

```
[FEN ""]
1. d4 f5 2. Nc3 Nf6

```

Your question as to why it isn't played more in the Dutch/more against the Blackmar-Diemer is a bit difficult to answer. Aside from the examples above where White or Black can sidestep this line, it can be reached in the main line of the Dutch against `2...d5` and the mainline of the Blackmar-Diemer with `2. e4`. It should be better for either White or Black, so why don't we see it more often?

In my opinion, I think that White has sufficient compensation for the pawn due to the weak e5 square and the possibilities of playing f3, undermining Black's pawn structure. If we go with this assumption, then we're looking at the first scenario in the Dutch Defense. I believe that there are more common replies to `1...f5` such as `2. g3` and `2. Nf3` which tend to score better than the gambit line outlined in the question.

On the flip side, I noticed that Black actually scores better with this line in practice, so I'm rather quite torn. I believe you've hit upon something rather original, and I encourage you to do a bit of studying into the lines yourself and arrive at your own conclusion :) maybe you have found a new main line!
> 6 votes

# Answer
I think it is important to stress that people writing a book about the Blackmar-Diemer Gambit will adopt a very different point of view than people studying the theory of the Dutch defense.

The Blackmar-Diemer Gambit, in spite of having some hardcore aficionadoes, is a dubious opening. When you study it or write a book about it, you are looking for lines where White can get some initiative and is not clearly worse. Hence, a tense position with some pitfalls for Black or an unclear position with some compensation for the pawn is exactly what you wish for.

I would say the position after 1.d4 d5 2.e4? de4 3.Nc3 f5?! 4.Bf4!? is exactly that: White obviously has some compensation for his pawn with a lead of two moves in development and Black being slightly weakened by f7-f5. My bet is that the objective evaluation is about equality, but one could also argue for a slight edge for either side - I haven't seen Scheerer's analysis but in any case he has no reason not to be enthousiastic about White's perspectives here. At the very least, since there is no forcing play going on, it is pretty sure that Black doesn't have a direct refutation.

Playing Black, I would never consider 3...f5 here: there are so many easier ways (3...Nf6, 3...e5, 3...Bf5) to handle the BDG, with good prospects for an advantage, that entering such an unclear line is totally unpractical.

In the Dutch, by contrast, Black is often playing with some preparation (otherwise it is too dangerous) and he is pretty happy to reach an equal or double-edged position. That's why, from a theoretical point of view, 1.d4 f5 2.Nc3 d5 3.e4 de4 4.Bf4 is not met very often. White has many other options to try and get some initiative, e.g. 3.Bf4 immediately.
> 1 votes

# Answer
Old question, but up my alley, so I am going to give you my opinion.

First, Stockfish 10 evaluates this as roughly equal (-.08 at a depth of 35), but that is not really the end of the story. White is down a solid pawn, but only down on the eval by -.08? Well, that means that he has +.92 in positional compensation, assuming that black tries to keep the pawn, so let's look at that positional compensation.

People are not computers, so while it is almost equal, virtually no strong player would want to play black there since it looks dangerous. The best move for white is 4.Bg5!, which inhibits black's development even more since it prevents e6 and developing the king-side, or after the relatively-forced Nf6, it will threaten to get the pawn back, but we will talk about that later. If black tries to get by without Nf6, it may even be worse.

The Bc8 has been made bad, and the king-side has been weakened grossly by f5. So, not only has the h5-e8 diagonal been weakened some, but also the a2-g8 diagonal will be a nice for a Bc4 move in the near future. None of those things appeal to a human Master's eye since experience tells me that black's position would be very dangerous if he tries to keep the material.

The reason this variation for white is not more popular is that with best play, white only gets his pawn back with no real advantage. The reason this position is not more popular for black is that if you are going to defend this, there is a much better way with Bf5 soon that does not weaken the king-side with f5?!, so why do that? The best defense is generally considered to be the Gunderam Defense, which starts with 5...Bf5. Here is a sample line, and it is considered very solid for black.

```
 [FEN ""]
 1. d4 d5 2. e4 dxe4 3. Nc3 Nf6 4. f3 exf3 5. Nxf3 Bf5 6. Bc4 e6 7. O-O c6 8. Ne5 Bg6 9. Bg5 Be7

```
> 1 votes

# Answer
It seems that Black has weakened his light squares and fallen behind in development. I evaluate this position as equal. Black holds onto the extra pawn, but he also weakens his position.
> 0 votes

---
Tags: opening, dutch-defense
---


# Question
Title: Is this queen endgame a win or a draw for White?
```
[FEN "6k1/8/4qp1p/7P/6P1/5P2/6K1/Q7 w - - 0 1"]

```

I am unable to analyze this queen endgame in which it is White's turn. Is it a win or a draw for White?

# Answer
I analyzed your position with Stockfish 11 ("Stockfish\_20011801\_x64\_modern" to be exact) to a depth of 78 and it returned the following line as the best continuation.

```
6k1/8/4qp1p/7P/6P1/5P2/6K1/Q7 w - - 0 1

1. Qa8+ Kf7 2. Qb7+ Kg8 3.Qb8+ Kf7 4. Qb1 Qe2+ 5. Kg3 Qe5+ 6. Kf2 Qh2+ 7. Ke3 Qe5+ 8. Qe4 Qc5+ 9. Ke2 Qb5+ 10. Kf2 Qb2+ 11. Kg3 Qa1 12. Qc4+ Ke7 13. Qc7+ Ke6 14. Kg2 Qb2+ 15.Kh3 Qf2 16. Qc4+ Kd6 17. Qe4 Qg1 18. Qb4+ Ke6 19. Qc4+ Ke7 20. Qd3 Qh1+ 21.Kg3 Qa1 22. Qe3+ Kd7 23. Qe4 Qa5 24. Qd3+ Ke6 25. Qe3+ Kd7 26.Kh3 Qb5 27.Qe4 Qf1+ 28. Kg3 Kd6 29. Kf4 Qb5 30. Qd4+ Ke7 31.Qe3+ Kf7 32.Kg3 Qb8+ 33.Qf4 Qb6 34. Qc4+ Kg7 35. Kf4 Qb8+ 36. Ke3 Qa7+ 37. Qd4 Qb7 38.Kf2 Qc7 39.Qb4 Qh2+ 40. Ke3 Qg1+ 41. Ke4 Qa7 42. Qd6 Qa4+ 43. Ke3 Qb3+ 44.Qd3 Qe6+ 45. Kd2 Qa2+ 46. Ke1 Qa1+ 47. Kf2 Qb2+ 48. Kg3 Qb8+ 49. Kg2 Kf7 *

```

As you can see by playing through the variation, no progress ends up being made and the game one way or another ends up drawn through the 50-move rule (I say one way or another because white theoretically could push say the f pawn at the end of the variation showed and restart the 50-move rule).
> 3 votes

---
Tags: analysis, draw, queen-endgame
---


title: When is castling needed?

text:
# Question
Title: When is castling needed?
I am a rookie in chess. I can't understand why castling is needed.

In what scenarios is castling useful?

# Answer
> 32 votes
Castling is extremely useful in almost all games. It lets you do two things at once. First, it moves your king from the center to the side of the board, where it is much more difficult to attack for the opponent. Second, it brings one of your rooks towards the center of the board, and it crucial in bringing both of your rook into the game.

There may be a number of potential reasons why these points might not make sense to you. Here is an (incomplete) list:

a) you do not feel that the king is in danger in the center

b) you feel that the danger on the side of the board is the same

c) you feel that activating the rook is not too useful

For a) you should probably have a look at how to attack if the king stays in the center; develop, try to rip open the center e.g., by advancing (even at the cost of sacrificing) some pawns in the center. Once you find out how to do this and also experience how it feels being torn apart by such an attack, you will appreciate being able to quickly move the king out of the center.

For b) it is important to understand that, generally, the initial pawn positions on the 2nd/7th rank are the most resistant. It might be that you unnecessarily weaken the protection of your king by pawn moves here. Also you should have a look at some standard motifs, such as the classic bishop sacrifice (google the keyword). Avoid such configurations and do not push the pawns in front of your king too much and you will soon realize that the side of the board is a much safer place to be.

Finally, concerning c), it is a sad truth that many players do not use all or even most of their pieces. Having a rook stuck in a corner essentially amounts to having a piece less; for attack and for defense. You should strive to activate all your pieces and also to connect the rooks, possibly even double them on an open file. For this, castling is the single most effective means. All other ways to activating and connecting the rooks likely take both more moves and require additional, potentially weakening, pawn moves.

# Answer
> 5 votes
Castling is a way of strengthening your King for its' defensive position and Rook's position for its' attacking position(Coming to the game)

**Types of Castling**

*King Side* denoted by `O-O` since the King is moving two squares towards the King-side Rook.

*Queen Side* denoted by `O-O-O` since the King is moving two squares towards the Queen-side Rook.

**When not to castle**

***Legal Check***

* When your King or Rook has moved earlier
* When the King is under check
* When the square the king will move to or move over is attacked by an enemy piece

**Why to castle**

***Strategy Check***

* If you want to go with `attacking mindset`, wait for the enemy's end to castle and do the castling on the alternative end of your side. Push the pieces and target his weak squares protecting the King i.e. The three pawns protecting the king.
* If you want to play with a `defensive mindset`, cover all your pawn structure ahead of king with Knights and Bishop.

General tip: Move the a-file or h-file pawn in case of a `waiting move` for the King to escape back rank mate at the later stage.

# Answer
> 5 votes
I castle in most games, but I'll be a contrarian and mention when/why I don't like to castle...

## When/why not to castle:

* **to use the tempo for something else** I think a lot of people castle too early, often using it as a "well I don't know what to do next" move. Think about what you'll want to do after you castle, and see if there might be a tactic that might benefit from having a move earlier. Alternatively, think about what your opponent wants to do next, and thwart their development/tactic.
* **to make your opponent commit to an attack** By waiting to castle, you can sometimes force your opponent to commit to attacking either king side or queen side before they know where your king will be. I find this especially useful in games where I've dominated the center, since then the opponent needs to take more time to move pieces to the opposite side (when I castle away from their development). Note that it's easier to get that domination with the extra tempo you get from not castling.
* **to make your opponent more aggressive** Often, seeing you not castle, an opponent will try to "punish" you for your indiscretion. If you get experience with people trying to punish you for not castling, you'll have an advantage and might find some fun tactics to use to punish them for punishing you
* **when the game is simplifying fast** If, for whatever reason, pieces are leaving the board in a hurry, having your king in the center of the board can give you an advantage in the endgame--your king is only a few moves away from most of the action.
* **for a variation on your opening** If you want to mix things up in an opening, try not castling and see what sort of attacks that gives you.
* **if you want to use your rooks in the corners of the board to attack** h4 is a common move to attack a castled black king, but obviously it's much weaker if you castle king side. a4 can also start an interesting queen side attack, and sometimes the options of both of these attacks can outweigh the extra flak your king may get in the center

To answer the actual question...

## Why castle:

* **the side of the board is the best defense for your King** If your king is in the corner, there are only two directions attacks can come from. In the center, there are three directions. This simplification can make defense easier.
* **it's easier to see attacks coming** This is closely related to the above; a knight in the middle of the board might be one move away from check while also controlling the center and threatening an exchange or two. If your king is still in the center, it's harder to know what your opponent is thinking. If your king has castled, they have to commit their pieces to a side to attack it, so you can identify your opponent's intentions more easily.
* **connecting and activating your rooks** Activating your rooks is good; connecting your rooks is better. With connected rooks (rooks that defend eachother), you can start putting rooks on contested open files and get to worry a bit less about the exchange.
* **to throw your opponent off** Castling is the only move where two piece move at once. Additionally, your most important piece is moving at double its normal speed. If your opponent is attacking your defenses based on where your pieces currently are, castling can instantly drastically change your configuration. It can neutralize a double-attack to f2 while also removing a c3 pin (perhaps your knight with a black bishop behind it). Used well, you can waste a few of your opponent's moves in one fell swoop.

## Some games to look at:

* The Game of the Century I certainly didn't see Fischer's attack coming
* Under the Cannon This is often considered one of the best examples of Alekhine's gun--notice how late white castled, and how black tried to get his king back into the action quite a bit later. And notice how castling made black's queen misplaced. Also, of course, it's known as an example of an impressive use of activated rooks.
* Fischer v Spassky Look at how Spassky started a strong attack before castling, and also how Fischer punished him for it. I think Spassky's attack was brilliant, and a good example of why one might wait a bit to castle, but Fischer is obviously brilliant too and great at pursuing even the smallest of weaknesses in his opponents.

*I'll add inline games when I figure out how to do so*

# Answer
> 2 votes
Castling is good for protecting your king.

It's good to castle your king early in the game.

Castling is good for getting your king out of the center.

Castling isn't mandatory, but it is ideal to castle.

Also Castling helps to get one of your rooks activated.

I hope this helped you!

# Answer
> 1 votes
Castling is good and very effective tool.

Use it at proper time. Don't go by default (starting point). You have to plan your game accordingly.

It will close the door and put king in very secure place. But remember most secure place is also most dangerous, as now king moving block is less.

And you should keep it in habit of playing with castling. And you'll soon learn its advantage.

# Answer
> 1 votes
Just for practice my brother and I would take turns opening with a castling as soon as possible. While the other practiced attacking the position. This was an effective challenge to developing both of our skills in defending and defeating the move.

I do think too often many players use castling as an escape from attack. IMHO this is only a prolonging of the inevitable. It may prolong the game and a good player can easily continue an attack when castling is used to escape.

Castling should be planned as an element of defense in the overall game. The most obvious factor is to which side to castle. Often based on the attack approach of the opponent.

Just FYI, for some damn reason I prefer the King's side. Would be nice to see a vote on this. And tie it to right handed and left handed persons.

# Answer
> 1 votes
Here is a simple rule: Always castle until you are sufficiently strong to understand when not to castle. When you are castled, do not move the pawns in front of your king unless you have a very good reason do do so.

# Answer
> 1 votes
It's also important to note that castling is not always required. Once you reach about 1800-2000 level, you'll start to see that in certain (closed) positions, like in some variations of the French, moving the king up and manually connecting your rooks may be required/favored. However, even in those positions, castling is generally a good idea.

The only reason you wouldn't castle is if the position is very closed and you have a specific role for the king that wouldn't cause it unnecessary danger and/or if your pieces are on the other side of the board and you can defend your king better if it manually shifted over by a square or two.

However, this requires deep positional understanding and tactical sacrificial understanding (your opponents potential sacs), so as a general rule, I'd advise for castling.

However, develop your pieces to take key squares away from your opponent first, then castle. Don't castle just because you can, but because you should. However, in the opening, sometimes other priorities are more important, like a crucial square, winning a piece, forcing your opponent to play other moves to gain tempo, etc.

# Answer
> 0 votes
You can castle in chess to the left, or to the right.

```
 8/8/8/8/8/2N2NP1/PPP2PBP/2KR1RK1 w - - 0 1

```

The other pieces denote specific formations that are good.

The main reasons for castling are these:

1. To protect the king.
2. To get the Rook into action

---
Tags: strategy, castling, kings, defense
---


# Question
Title: Is it possible to castle with checkmate?
I am new to chess. Please answer this for me:

> Is it possible to castle with checkmate?

# Answer
> 24 votes
I can think of two questions you might be meaning to ask, given the wording of your question. Maybe neither of these is what you're after, but just in case:

**1. Is it possible to castle out of check or even checkmate?** Here the answer is *no*. If your king is in check, then castling is not a legal move.

**2. Is it possible to castle while checkmating your opponent?** Here the answer is *yes*, it is possible, though it does not happen often. For instance, the game Ed.Lasker-Thomas (1912), with its famous queen sacrifice and king hunt, could have finished with a castling mate:

```
[fen ""]
1. d4 e6 2. Nf3 f5 3. Nc3 Nf6 4. Bg5 Be7 5. Bxf6 Bxf6 6. e4
fxe4 7. Nxe4 b6 8. Ne5 O-O 9. Bd3 Bb7 10. Qh5 Qe7 11. Qxh7+
Kxh7 12. Nxf6+ Kh6 13. Neg4+ Kg5 14. h4+ Kf4 15. g3+ Kf3
16. Be2+ Kg2 17. Rh2+ Kg1 18. Kd2# (18.O-O-O#)1-0

```

# Answer
> 3 votes
If you I asking whether it is legal to castle out of checkmate if it is the only option then no the same rules apply as with check although I can't really think of many instances where you would be able to castle to prevent checkmate...

# Answer
> 3 votes
No-if check mate for your king. Yes- if check mate for opponent's king

# Answer
> 2 votes
This was achieved by Eric Rosen (IM) on his Twitch stream, uploaded to YouTube Dec 2019. https://www.youtube.com/watch?v=UxZc7ZF2uOY

# Answer
> 0 votes
Yes, it clearly is possible. Here is a position where White has just castled, and checkmated.

```
    8/8/8/8/8/8/R7/2KR2k1 w - - 0 1

```

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


# Question
Title: Is castling possible with a pawn promoted to a rook?
I was thinking about some rules and I came up with a really nice question. Is it possible to castle with a pawn promoted to a rook?

If the rules are followed-neither the king or the new rook has moved and king doesn’t move out of or through check-to me it seems to be a legal move.

If it possbile, how would this castling look like? I suspect that the king would go to e3, and the new rook would go to e2, starting from the below diagram.

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

1. e8=R

```

# Answer
No, according to FIDE's Laws of Chess, castling has to be done along the first rank.

§3.8.2:

> 3.8.2 by ‘castling’. This is a move of the king and either rook of the same colour along the player’s first rank, counting as a single move of the king and executed as follows: the king is transferred from its original square two squares towards the rook on its original square, then that rook is transferred to the square the king has just crossed.
>
> 3.8.2.1 The right to castle has been lost:
>
> 3.8.2.1.1 if the king has already moved, or
>
> 3.8.2.1.2 with a rook that has already moved.
>
> 3.8.2.2 Castling is prevented temporarily:
>
> 3.8.2.2.1 if the square on which the king stands, or the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces, or
>
> 3.8.2.2.2 if there is any piece between the king and the rook with which castling is to be effected.
> 15 votes

# Answer
This question really needs a diagram with this position:

```
[FEN "8/8/4P3/3p4/2p3p1/1pP1kPPp/1P5P/R3K2R w KQkq - 0 1"]

```

White to mate in 3.

Tim Krabbé and Max Pam found the loophole in the rules that you are asking about -- when they composed this problem in 1972, the promoted rook did indeed enable castling, as the rules only talked about a rook that hadn't moved yet! The rule was changed because of this problem.

The solution is beautiful as there are three different castlings involved:

1. 1.e7 Kd3 2.e8=R gxf3 3.0-0-0#.
2. 1.e7 Kxf3 2.e8=R d4 3.0-0#.
3. 1.e7 Kxf3 2.e8=R Kg2 3.0-0-0-0#!.
> 19 votes

# Answer
It used to be a thing(Krabbe), but FIDE edited its rules to be more specific, so that a king could only castle sideways. So, sadly, it isn't possible nowadays.
> 2 votes

---
Tags: rules, castling, pawn-promotion, loopholes
---


# Question
Title: Is it possible to win with a king and one bishop vs a king?
Are there any possible moves to checkmate a Black opponent if we have a White bishop and king?

# Answer
> 10 votes
No. There is no position you can construct in which the black king is in check (has to be from the bishop), white only has king and bishop and the black king can't move.

The closest you can get is this:

```
[fen "k7/1BK5/8/8/8/8/8/8 w - - 0 1"]

```

And the black king can move to a7.

# Answer
> 6 votes
There is no way to force a win with KB vs K.

No way for them to blunder into it.

No way for them to help you selfmate.

# Answer
> 1 votes
It is impossible. The Black king cannot be checkmated. In the case that the Black king goes into the 'right' corner, then it may be checked by the bishop. However, it must have at least 1 escape square. In the wrong corner, then Black cannot be checkmated no matter what.

---
Tags: endgame, bishops, kings
---


title: Openings in King of the Hill

text:
# Question
Title: Openings in King of the Hill
As you probably know, "King of the hill" (KOTH) is a variant of chess where one can win either like in classical chess or by putting the king in the central squares, namely d4, e4, d5 and e5, by a legal move.

I would like to collect some information about opening in this variant. More precisely, we can try to answer the following questions.

1. What are some examples of opening which are reasonably good in normal chess but almost losing in KOTH?
2. Conversely, are there some examples of opening which are reasonably good in KOTH but almost losing in normal chess?

# Answer
> 6 votes
As mentioned already, most hypermodern openings (King's Indian, Modern, etc.) are dubious in KOTH, because they give the opponent too much space in the center.

Besides that there are gambits where the compensation mostly consists of better control of the center, which is of course more valuable in KOTH. Therefore, some of such gambits that are often considered to be slightly inferior to dubious in chess are good or even best moves in KOTH. Usually, the gambit pawn should be rejected in order to get a playable position. A few examples are:

Furthermore, openings/gambits which try to drive the opponent's king to the center can be close to losing in KOTH. A notable example is the Fried liver attack. After 7.Qf3+ black should play 7..Qf6! followed by Be6 instead of 7..Ke6 in order to threaten the exchange of the white queen and bishop, which gives black a considerable advantage.

In order to double check my evaluation of the above mentioned openings in King of the Hill, I used the multi-variant Stockfish fork that is also used for analysis on lichess.

# Answer
> 3 votes
Basically, controlling the centre becomes significantly more important in KOTH. The obvious reason is that you want to spot the opponent's king from reaching one of the centre squares, and more space may allow your king to quickly march to the centre.

With that in mind, some openings that are good in chess but bad in KOTH are:

* Grunfeld Defence
* King's Indian Defence
* Pirc Defence
* Nimzo Indian Defence
* Reti Opening

Your second question (openings good in KOTH but almost losing in normal chess) is much harder to answer. Since KOTH is basically a more demanding version of chess, it tends to be that only some openings are acceptable in KOTH (and not the other way around). The only openings would be where one side sacrifices a piece to get their king closer to the centre, but none come to mind.

# Answer
> 1 votes
In KOTH, the best opening are classical. Putting pawns in the centre will allow your king to safely march up and also stopping the opponent's king from entering the centre.

Gambits which sacrifise a piece for a large centre are good, such as the Halloween Gambit. It wins in KOTH, but is only remotely playable in standard chess.

---
Tags: opening, chess-variants, king-of-the-hill
---


title: King/Queen chess variation

text:
# Question
Title: King/Queen chess variation
In Canada, there is a variation of chess in which king and queen are swapped from the normal starting position. However, some argue this makes no difference. Canadians are split. So the question is:

> Does swapping king/queen from the onset affect the game?

# Answer
> 7 votes
This does not make any difference. Exchanging the positions of king and queen on both sides just corresponds to mirroring the whole game horizontally. Thus they are equivalent.

# Answer
> 1 votes
If both sides swap queen and king at the beginning, it is obviously still the same game, only mirrored in the middle. All theory would still be valid.

Practically, it would be incredibly annoying to anybody intimately familiar with the normal setup. Even more so than the common quarter turn of the board, where all the squares have the wrong colour.

If only one side swaps king and queen this would probably benefit white. White is usually the one who can open up lines first and in this chess version the black king would already be on the same line as the white queen.

# Answer
> 1 votes
Clearly there are trivial differences. Instead of playing `e4` for a sharp game, White would play `d4`. (See Ignaz' answer)

It would also be no different than allowing Black to move first with a normal setup. So no, it would make no difference.

# Answer
> 1 votes
It *can* make a difference with respect to castling. As others have said, we just have a mirror of the regular startup, so a regular e4 becomes d4 and so on.

That leaves the question what happens with castling? If this is just mirrored as well, then indeed there is no theoretical difference. So in this setup, what are the rules for castling?

There may still be a *practical* difference, because one has to mirror their usual opening setups or and/or middlegame plans. Apart from that, it will be the exact same game.

# Answer
> 0 votes
No, there is no difference at all theoretically since the game is mirrored, so the relation between the pieces is still the same. However, there is a practical difference. For players used to playing normal chess, they might instinctively play Nf3, but now, since the board is reversed, then he/she is playing Van Geet's opening, which is sub-optimal.

---
Tags: chess-variants
---


title: The Urusov Gambit

text:
# Question
Title: The Urusov Gambit
The curious Urusov Gambit seems something of a gimmick. A great article on it appears here

```

[Event "Urusov Gambit"]
[Site "Tehran IRI"]
[Date "2016.10.28"]
[Round "4.20"]
[White "Mashmooli, Kian"]
[Black "Nasri, Amin"]
[Result "0-1"]
[WhiteElo "2137"]
[BlackElo "2248"]
[ECO "C44"]
[FEN ""]

1.e4 e5 2.Bc4 Nf6 3.d4 exd4 4.Nf3

```

The same article observers "**With that the opening fell into disfavour at the highest levels of master competition, and today it is mostly seen in club play, where it racks up quick scores against inexperienced or unprepared opponents.**"

Certainly there are many chess sites advocating its adoption as a quick way for WHITE to get ahead. It's considered a common '*opening trick*' Yet "**Estrin's analysis revealed, however, a possible equalizing method for Black (with Panov's 4....d5) and suggested that some of the deepest lines might end in equality with best play.**"

Even with (4....d5) it seems difficult for WHITE to re-obtain equality. The opening can evolve into a Two Knights Defense (with 4....Nc6), albeit with a pawn exchanged for tempo.

**QUESTION**:

> Does lack of play at senior levels really suggest the gambit is not sound? Does anyone know of GMs who favour such a gambit? And would anyone be able to take us through some of the possible lines from this point as WHITE?

# Answer
> 4 votes
The gambit doesn't lose but it also doesn't gain much advantage. Black can play Nc6 and transpose into the two knight defense which is seen in the Italian and the scotch gambit. These lines have a lot of theory and grandmasters are comfortable that they can draw them. Thus, white struggles to find an advantage using this opening at the top level.

# Answer
> 1 votes
It suggests that strong players believe it doesn't give White much of a chance for an advantage.

# Answer
> 0 votes
This gambit is PLAYABLE, but it clearly isn't winning for White. Black clearly has a way to equalise, or to gain a small edge, or else this opening would be played at top level.

---
Tags: opening, gambits, two-knights
---


title: What is sufficient mating material?

text:
# Question
Title: What is sufficient mating material?
The FIDE chess rules describe that "The game is draw when a position is reached from which a checkmate cannot occur by any possible series of legal moves" (FIDE rule 9.6). This rules is sometimes referred to as "Insufficient mating material rule", and the material that results in draw based on this rule is described in Draws in all games. So this covers the case where even a helpmate (or checkmate by unskilled play) is not possible with the present material. So:

What is sufficient mating material, whereby a skilled player can force another skilled player into checkmate?

Some combinations are well known, like:

* K + Q vs. K
* K + R vs. K
* K + B(w) + B(b) vs. K

But is for example K + N + B vs. K sufficient mating material ?

# Answer
> 24 votes
Most basic first - this rule is the reason that *King vs King* is an immediate draw. Neither side has a piece to check with, let alone checkmate with. A position that is a draw because neither side can win is called a "dead position".

Playing against a bare king, a bishop or a knight is insufficient to checkmate with, and therefore K+B v K and K+N v K is always a dead position. Most online playing sites end there, and consider everything else winnable.

K+Q v K, K+R v K, K+B+B v K, K+B+N v K are all endings in which white can even *force* mate (see an overview of basic checkmates on Wikipedia). Because you ask for it explicitly, here is an example of a mate with N and B:

```
[FEN "k7/8/NKB5/8/8/8/8/8 b - - 0 1"]

```

There are some special cases. K+N+N v K is tricky -- white can't *force* mate, but mate is still possible:

```
[FEN "6k1/8/6K1/4N3/4N3/8/8/8 w - - 0 1"]

```

White plays **1.Nf6+**, and black avoids mate by going to f8. But if he goes into the corner with **1...Kh8??**, then **2.Nf7#** mates.

So K+N+N v K is basically always given an immediate draw by the player with the knights in a slow game, because he knows he won't win. It will be awarded a draw by the arbiter if black claims one based on rule G.6 \[the old "10.2", before july 1 2014\], if the other requirements of that rule are met, and it's trivial to make 50 moves without losing. But if black runs out of time, black loses. And in a blitz game where nobody is writing down moves to count them, that may happen.

K+B v K+B is also tricky:

```
[FEN "5B2/8/8/8/8/7K/8/6bk w - - 0 1"]

```

With the bishops on the same color, mate isn't possible. It's an immediate draw.

```
[FEN "8/5B2/8/8/8/7K/8/6bk w - - 0 1"]

```

But with opposite colored bishops it is: **1.Bd5#** mates.

In most other endgames it is possible to think of a way that one or both sides can be mated. In particular, if there are pawns, it is usually possible that one of them promotes and checkmates later. but there are exceptions:

```
[FEN "4k3/8/8/p1p1p1p1/P1P1P1P1/8/8/4K3 w - - 0 1"]

```

To a human it's immediately obvious that the kings will never be able to cross to the other side, so this is a dead position. Engines have no clue, though. Mine thinks white is minutely worse.

And in the recent question about sequences of forced moves, limulus proposed this position with an "infinite loop" of forced moves:

```
[FEN "8/6p1/1p3pPk/1P3Pp1/1Pp3p1/KpP3P1/1P6/8 - - - 0 0 "]

```

Neither king can break out of its jail -- so this is just another example of a dead position. Immediate draw.

# Answer
> 7 votes
The quote

> The game is draw when a position is reached from which a checkmate cannot occur by any possible series of legal moves

Is a good summary in itself. It is not just how much material e.g. white has, black's material is also important. For example, let's say white has a K+N and black has K and h-pawn. Black's time runs out. Black loses on time, because

> You can theoretically reach a position with the available material where black is checkmated

When one of the players only has a king left, then the situation is different. The following material is judged as enough for a checkmate when the side with the lone King runs out of time.

1. K+pawn vs K
2. K+knight+knight vs K
3. K+bishop+knight vs K
4. K+the bishop pair vs K
5. K+rook vs K
6. K+queen vs K

(Edited to be more precise)

# Answer
> 5 votes
One interesting forced mate which nobody has mentioned is K+N+N v K+P.

Provided the pawn is not far advanced the side with the 2 knights drives the opposing king towards a corner. At a certain point when the driving can be completed by K+N the other knight blockades the pawn. The K+N finish driving the opposing king into a corner, building a prison, say a1+b1 (i.e. the opposing king can only alternate between a1 and b1), with king on b3 and knight on a2. The blockading knight then comes over to help deliver checkmate with stalemate avoided because the pawn can move.

Similar game shown below:

```
[FEN "2k5/7p/2K1N3/5N2/8/8/8/8 w - - 0 1"]

1. Ne7+ Kb8
2. Kb6 h5
3. Nc5 h4
4. Nd7+ Ka8
5. Nd5 h3
6. Nc7#

```

# Answer
> 3 votes
K+N+B, K+B+B, K+R, K+Q, and K+N+N are. The latter is a helpmate.

K+N and K+B are insufficient.

# Answer
> 2 votes
AFAIK sufficient mating material is considered as such if a "helpmate" can be demonstrated in any number of moves. Put another way, it is as if the player that ran out of time is out of the game, and now the other player controls both sides. If a checkmate position can be reached this way, that other player wins the game, otherwise it's a draw.

# Answer
> 0 votes
The minimum needed is Knight and Bishop, though N+N+KvK+P is also possible. Perhaps N+KvK+P will sometimes happen, but the standard minimum is N+B

---
Tags: rules, checkmate, draw, material-balance, dead-position
---


# Question
Title: What is the longest checkmate problem a human has composed?
Well, I looked at some long checkmates, and I wonder, what is the longest checkmate a human has composed?

# Answer
> 14 votes
The longest known checkmate problem composed by a human is dependent on a few criteria that are generally used by chess composers. Namely, it is a question of whether or not you want the problem to have a unique solution, meaning that there is only one possible solution with Black defending optimally, and if you want the position to be legal or not, meaning that it is reachable from the starting position. Another consideration is whether or not promoted pieces are allowed, as most composers try to not use them. Finally, it is also debatable whether or not an illegal position must have only pieces from the chess box, with pawns being converted as needed.

Here is a selection of a few problems that fall along these lines.

This is the longest legal problem with a unique solution and no promoted pieces.

```
[Title "Walther Jørgensen, Thema Danicum 1982, Mate In 226"]
[fen "1N2Q3/p6n/p5n1/p1p2rpb/p4k1r/K1P4p/2PP4/6B1 w - - 0 1"]

1. Bh2+! Kf3 2. Qe3+ Kg2 3. Qg1+ Kf3 4. Qf1+ Kg4 5. Qe2+ Rf3 6. Qe6+ Rf5 7. Nd7 Kf3 8. Qe3+ Kg2 9. Qg1+ Kf3 10. Qf1+ Kg4 11. Qe2+ Rf3 12. Qe6+ Rf5 13. Kb2! Kf3 14. Qe3+ Kg2 15. Qg1+ Kf3 16. Qf1+ Kg4 17. Qe2+ Rf3 18. Qe6+ Rf5 19. Kc1! Kf3 20. Qe3+ Kg2 21. Qg1+ Kf3 22. Qf1+ Kg4 23. Qe2+ Rf3 24. Qe6+ Rf5 25. Kd1! a3! 26. Kc1 Kf3 27. Qe3+ Kg2 28. Qg1+ Kf3 29. Qf1+ Kg4 30. Qe2+ Rf3 31. Qe6+ Rf5 32. Kb1 Kf3 33. Qe3+ Kg2 34. Qg1+ Kf3 35. Qf1+ Kg4 36. Qe2+ Rf3 37. Qe6+ Rf5 38. Ka2 Kf3 39. Qe3+ Kg2 40. Qg1+ Kf3 41. Qf1+ Kg4 42. Qe2+ Rf3 43. Qe6+ Rf5 44. Kxa3 Kf3 45. Qe3+ Kg2 46. Qg1+ Kf3 47. Qf1+ Kg4 48. Qe2+ Rf3 49. Qe6+ Rf5 50. Kb2 Kf3 51. Qe3+ Kg2 52. Qg1+ Kf3 53. Qf1+ Kg4 54. Qe2+ Rf3 55. Qe6+ Rf5 56. Kc1 Kf3 57. Qe3+ Kg2 58. Qg1+ Kf3 59. Qf1+ Kg4 60. Qe2+ Rf3 61. Qe6+ Rf5 62. Kd1 a4! 63. Kc1 Kf3 64. Qe3+ Kg2 65. Qg1+ Kf3 66. Qf1+ Kg4 67. Qe2+ Rf3 68. Qe6+ Rf5 69. Kd1 a5! 70. Kc1 Kf3 71. Qe3+ Kg2 72. Qg1+ Kf3 73. Qf1+ Kg4 74. Qe2+ Rf3 75. Qe6+ Rf5 76. Kd1 a6! 77. Kc1 Kf3 78. Qe3+ Kg2 79. Qg1+ Kf3 80. Qf1+ Kg4 81. Qe2+ Rf3 82. Qe6+ Rf5 83. Kd1 a3 84. Kc1 Kf3 85. Qe3+ Kg2 86. Qg1+ Kf3 87. Qf1+ Kg4 88. Qe2+ Rf3 89. Qe6+ Rf5 90. Kb1 Kf3 91. Qe3+ Kg2 92. Qg1+ Kf3 93. Qf1+ Kg4 94. Qe2+ Rf3 95. Qe6+ Rf5 96. Ka2 Kf3 97. Qe3+ Kg2 98. Qg1+ Kf3 99. Qf1+ Kg4 100. Qe2+ Rf3 101. Qe6+ Rf5 102. Kxa3 Kf3 103. Qe3+ Kg2 104. Qg1+ Kf3 105. Qf1+ Kg4 106. Qe2+ Rf3 107. Qe6+ Rf5 108. Kb2 Kf3 109. Qe3+ Kg2 110. Qg1+ Kf3 111. Qf1+ Kg4 112. Qe2+ Rf3 113. Qe6+ Rf5 114. Kc1 Kf3 115. Qe3+ Kg2 116. Qg1+ Kf3 117. Qf1+ Kg4 118. Qe2+ Rf3 119. Qe6+ Rf5 120. Kd1 a4! 121. Kc1 Kf3 122. Qe3+ Kg2 123. Qg1+ Kf3 124. Qf1+ Kg4 125. Qe2+ Rf3 126. Qe6+ Rf5 127. Kd1 a5! 128. Kc1 Kf3 129. Qe3+ Kg2 130. Qg1+ Kf3 131. Qf1+ Kg4 132. Qe2+ Rf3 133. Qe6+ Rf5 134. Kd1 a3 135. Kc1 Kf3 136. Qe3+ Kg2 137. Qg1+ Kf3 138. Qf1+ Kg4 139. Qe2+ Rf3 140. Qe6+ Rf5 141. Kb1 Kf3 142. Qe3+ Kg2 143. Qg1+ Kf3 144. Qf1+ Kg4 145. Qe2+ Rf3 146. Qe6+ Rf5 147. Ka2 Kf3 148. Qe3+ Kg2 149. Qg1+ Kf3 150. Qf1+ Kg4 151. Qe2+ Rf3 152. Qe6+ Rf5 153. Kxa3 Kf3 154. Qe3+ Kg2 155. Qg1+ Kf3 156. Qf1+ Kg4 157. Qe2+ Rf3 158. Qe6+ Rf5 159. Kb2 Kf3 160. Qe3+ Kg2 161. Qg1+ Kf3 162. Qf1+ Kg4 163. Qe2+ Rf3 164. Qe6+ Rf5 165. Kc1 Kf3 166. Qe3+ Kg2 167. Qg1+ Kf3 168. Qf1+ Kg4 169. Qe2+ Rf3 170. Qe6+ Rf5 171. Kd1 a4 172. Kc1 Kf3 173. Qe3+ Kg2 174. Qg1+ Kf3 175. Qf1+ Kg4 176. Qe2+ Rf3 177. Qe6+ Rf5 178. Kd1 c4! 179. Kc1 Kf3 180. Qe3+ Kg2 181. Qg1+ Kf3 182. Qf1+ Ke4! 183. Qxc4+ Kf3 184. Qf1+ Kg4 185. Qe2+ Rf3 186. Qe6+ Rf5 187. Kd1 a3 188. Kc1 Kf3 189. Qe3+ Kg2 190. Qg1+ Kf3 191. Qf1+ Kg4 192. Qe2+ Rf3 193. Qe6+ Rf5 194. Kb1 Kf3 195. Qe3+ Kg2 196. Qg1+ Kf3 197. Qf1+ Kg4 198. Qe2+ Rf3 199. Qe6+ Rf5 200. Ka2 Kf3 201. Qe3+ Kg2 202. Qg1+ Kf3 203. Qf1+ Kg4 204. Qe2+ Rf3 205. Qe6+ Rf5 206. Kxa3 Kf3 207. Qe3+ Kg2 208. Qg1+ Kf3 209. Qf1+ Kg4 210. Qe2+ Rf3 211. Qe6+ Rf5 212. Kb2 Kf3 213. Qe3+ Kg2 214. Qg1+ Kf3 215. Qf1+ Kg4 216. Qe2+ Rf3 217. Qe6+ Rf5 218. Kc1 Kf3 219. Qe3+ Kg2 220. Qg1+ Kf3 221. Qf1+ Kg4 222. Qe2+ Rf3 223. Qe6+ Rf5 224. Kd1 Nf8,Nf6 225. Nf6+ Kf3 226. Qe2#

```

Based off of an earlier mate in 292 with an illegal position, this mate in 257 has as legal position with some minor duals in the solution.

```
[Title "Ottó Titusz Bláthy, Vielzügige Schachaufg 1889, Mate In 257 Legal Version of the #292"]
[FEN "q5nn/1pk1p3/p3P1p1/P3rpP1/1Kp1pP1p/8/2PQ1PP1/8 w - - 0 1"]

1. Qd7+ Kb8 2. Qd8+ Ka7 3. Qd4+ Rc5 4. Qxc5+ Kb8 5. Qe5+ Kc8 6. Qd5 Kc7 7. Qd7+ Kb8 8. Qd8+ Ka7 9. Qb6+ Kb8 10. c3 Kc8 11. Qc5+ Kb8 12. Qe5+ Kc8 13. Qd5 Kc7 14. Qd7+ Kb8 15. Qd8+ Ka7 16. Qb6+ Kb8 17. Ka3 Kc8 18. Qc5+ Kb8 19. Qe5+ Kc8 20. Qd5 Kc7 21. Qd7+ Kb8 22. Qd8+ Ka7 23. Qb6+ Kb8 24. Kb2 Kc8 25. Qc5+ Kb8 26. Qe5+ Kc8 27. Qd5 Kc7 28. Qd7+ Kb8 29. Qd8+ Ka7 30. Qb6+ Kb8 31. Kc1 Kc8 32. Qc5+ Kb8 33. Qe5+ Kc8 34. Qd5 Kc7 35. Qd7+ Kb8 36. Qd8+ Ka7 37. Qb6+ Kb8 38. Kd1 Kc8 39. Qc5+ Kb8 40. Qe5+ Kc8 41. Qd5 Kc7 42. Qd7+ Kb8 43. Qd8+ Ka7 44. Qb6+ Kb8 45. Ke2 Kc8 46. Qc5+ Kb8 47. Qe5+ Kc8 48. Qd5 Kc7 49. Qd7+ Kb8 50. Qd8+ Ka7 51. Qb6+ Kb8 52. Kf1 Kc8 53. Qc5+ Kb8 54. Qe5+ Kc8 55. Qd5 Kc7 56. Qd7+ Kb8 57. Qd8+ Ka7 58. Qb6+ Kb8 59. Kg1 Kc8 60. Qc5+ Kb8 61. Qe5+ Kc8 62. Qd5 Kc7 63. Qd7+ Kb8 64. Qd8+ Ka7 65. Qb6+ Kb8 66. Kh2 Kc8 67. Qc5+ Kb8 68. Qe5+ Kc8 69. Qd5 Kc7 70. Qd7+ Kb8 71. Qd8+ Ka7 72. Qb6+ Kb8 73. Kh3 Kc8 74. Qc5+ Kb8 75. Qe5+ Kc8 76. Qd5 Kc7 77. Qd7+ Kb8 78. Qd8+ Ka7 79. Qb6+ Kb8 80. Kxh4 Kc8 81. Qc5+ Kb8 82. Qe5+ Kc8 83. Qd5 Kc7 84. Qd7+ Kb8 85. Qd8+ Ka7 86. Qb6+ Kb8 87. Kh3 Kc8 88. Qc5+ Kb8 89. Qe5+ Kc8 90. Qd5 Kc7 91. Qd7+ Kb8 92. Qd8+ Ka7 93. Qb6+ Kb8 94. Kh2 Kc8 95. Qc5+ Kb8 96. Qe5+ Kc8 97. Qd5 Kc7 98. Qd7+ Kb8 99. Qd8+ Ka7 100. Qb6+ Kb8 101. Kg1 Kc8 102. Qc5+ Kb8 103. Qe5+ Kc8 104. Qd5 Kc7 105. Qd7+ Kb8 106. Qd8+ Ka7 107. Qb6+ Kb8 108. Kf1 Kc8 109. Qc5+ Kb8 110. Qe5+ Kc8 111. Qd5 Kc7 112. Qd7+ Kb8 113. Qd8+ Ka7 114. Qb6+ Kb8 115. Ke2 Kc8 116. Qc5+ Kb8 117. Qe5+ Kc8 118. Qd5 Kc7 119. Qd7+ Kb8 120. Qd8+ Ka7 121. Qb6+ Kb8 122. Kd1 Kc8 123. Qc5+ Kb8 124. Qe5+ Kc8 125. Qd5 Kc7 126. Qd7+ Kb8 127. Qd8+ Ka7 128. Qb6+ Kb8 129. Kc1 Kc8 130. Qc5+ Kb8 131. Qe5+ Kc8 132. Qd5 Kc7 133. Qd7+ Kb8 134. Qd8+ Ka7 135. Qb6+ Kb8 136. Kb2 Kc8 137. Qc5+ Kb8 138. Qe5+ Kc8 139. Qd5 Kc7 140. Qd7+ Kb8 141. Qd8+ Ka7 142. Qb6+ Kb8 143. Ka3 Kc8 144. Qc5+ Kb8 145. Qe5+ Kc8 146. Qd5 Kc7 147. Qd7+ Kb8 148. Qd8+ Ka7 149. Qb6+ Kb8 150. Kb4 Kc8 151. Qc5+ Kb8 152. Qe5+ Ka7 153. Qd4+ Kb8 154. Qxh8 Kc7 155. Qe5+ Kc8 156. Qd5 Kb8 157. Qd8+ Ka7 158. Qb6+ Kb8 159. Ka3 Kc8 160. Qc5+ Kb8 161. Qe5+ Kc8 162. Qd5 Kc7 163. Qd7+ Kb8 164. Qd8+ Ka7 165. Qb6+ Kb8 166. Kb2 Kc8 167. Qc5+ Kb8 168. Qe5+ Kc8 169. Qd5 Kc7 170. Qd7+ Kb8 171. Qd8+ Ka7 172. Qb6+ Kb8 173. Kc1 Kc8 174. Qc5+ Kb8 175. Qe5+ Kc8 176. Qd5 Kc7 177. Qd7+ Kb8 178. Qd8+ Ka7 179. Qb6+ Kb8 180. Kd1 Kc8 181. Qc5+ Kb8 182. Qe5+ Kc8 183. Qd5 Kc7 184. Qd7+ Kb8 185. Qd8+ Ka7 186. Qb6+ Kb8 187. Ke2 Kc8 188. Qc5+ Kb8 189. Qe5+ Kc8 190. Qd5 Kc7 191. Qd7+ Kb8 192. Qd8+ Ka7 193. Qb6+ Kb8 194. Kf1 Kc8 195. Qc5+ Kb8 196. Qe5+ Kc8 197. Qd5 Kc7 198. Qd7+ Kb8 199. Qd8+ Ka7 200. Qb6+ Kb8 201. Kg1 Kc8 202. Qc5+ Kb8 203. Qe5+ Kc8 204.Qd5 Kc7 205. Qd7+ Kb8 206. Qd8+ Ka7 207. Qb6+ Kb8 208. Kh2 Kc8 209. Qc5+ Kb8 210. Qe5+ Kc8 211. Qd5 Kc7 212. Qd7+ Kb8 213. Qd8+ Ka7 214. Qb6+ Kb8 215. Kh3 Kc8 216. Qc5+ Kb8 217. Qe5+ Kc8 218. Qd5 Kc7 219. Qd7+ Kb8 220. Qd8+ Ka7 221. Qb6+ Kb8 222. g4 Kc8 223. Qc5+ Kb8 224. Qe5+ Kc8 225. Qd5 Kc7 226. Qd7+ Kb8 227. Qd8+ Ka7 228. Qb6+ Kb8 229. gxf5 gxf5 230. Kh4 Kc8 231. Qc5+ Kb8 232. Qe5+ Kc8 233. Qd5 Kc7 234. Qd7+ Kb8 235. Qd8+ Ka7 236. Qb6+ Kb8 237. Kh5 Kc8 238. Qc5+ Kb8 239. Qe5+ Kc8 240. Qd5 Kc7 241. Qd7+ Kb8 242. Qd8+ Ka7 243. Qb6+ Kb8 244. Kg6 Kc8 245. Qc5+ Kb8 246. Qe5+ Kc8 247. Qd5 Kc7 248. Qd7+ Kb8 249. Qd8+ Ka7 250. Qb6+ Kb8 251. Kf7 Kc8 252. Ke8 Kb8 253. Kd7 e3 254. fxe3 Nf6+ 255. gxf6 exf6  256. e7 Qa7 257. e8=Q#

```

Here is the longest problem that has a promoted piece and some minor duals in the solution.

```
[Title "Nenad Petrovic, Zagreb 1969, Mate In 271"]
[FEN "8/Bk3p1p/1P3p2/KP2n2p/1P1p4/1Pp2p2/B1P5/7B w - - 0 1"]

1. Bb1 h4 2. Ka4 Ka8 3. Ka3 Kb7 4. Ka2 Ka8 5. Ka1 Kb7 6. Ba2 Ka8 7. Kb1 Kb7 8. Kc1 Ka8 9. Kd1 Kb710. Ke1 Ka8 11. Bb1 Kb7 12. Kf1 Ka8 13. Kf2 Kb7 14. Ke1 Ka8 15. Kd1 Kb7 16. Kc1 Ka8 17. Ba2 Kb7 18. Kb1 Ka8 19. Ka1 Kb7 20. Bb1 Ka8 21. Ka2 Kb7 22. Ka3 Ka8 23. Ka4 Kb7 24. Ka5 f5 25. Ka4 Ka8 26. Ka3 Kb7 27. Ka2 Ka8 28. Ka1 Kb7 29. Ba2 Ka8 30. Kb1 Kb7 31. Kc1 Ka8 32. Kd1 Kb7 33. Ke1 Ka8 34. Bb1 Kb7 35. Kf1 Ka8 36. Kf2 Kb7 37. Ke1 Ka8 38. Kd1 Kb7 39. Kc1 Ka8 40. Ba2 Kb7 41. Kb1 Ka8 42. Ka1 Kb7 43. Bb1 Ka8 44. Ka2 Kb7 45. Ka3 Ka8 46. Ka4 Kb7 47. Ka5 f4 48. Ka4 Ka8 49. Ka3 Kb7 50. Ka2 Ka8 51. Ka1 Kb7 52. Ba2 Ka8 53. Kb1 Kb7 54. Kc1 Ka8 55. Kd1 Kb7 56. Bb1 Ka8 57. Ke1 Kb7 58. Kf1 Ka8 59. Kf2 Kb7 60. Ke1 Ka8 61. Kd1 Kb7 62. Kc1 Ka8 63. Ba2 Kb7 64. Kb1 Ka8 65. Ka1 Kb7 66. Bb1 Ka8 67. Ka2 Kb7 68. Ka3 Ka8 69. Ka4 Kb7 70. Ka5 f6 71. Ka4 Ka8 72. Ka3 Kb7 73. Ka2 Ka8 74. Ka1 Kb7 75. Ba2 Ka8 76. Kb1 Kb7 77. Kc1 Ka8 78. Kd1 Kb7 79. Ke1 Ka8 80. Bb1 Kb7 81. Kf1 Ka8 82. Kf2 Kb7 83. Ke1 Ka8 84. Kd1 Kb7 85. Kc1 Ka8 86. Ba2 Kb7 87. Kb1 Ka8 88. Ka1 Kb7 89. Bb1 Ka8 90. Ka2 Kb7 91. Ka3 Ka8 92. Ka4 Kb7 93. Ka5 f5 94. Ka4 Ka8 95. Ka3 Kb7 96. Ka2 Ka8 97. Ka1 Kb7 98. Ba2 Ka8 99. Kb1 Kb7 100. Kc1 Ka8 101. Kd1 Kb7 102. Ke1 Ka8 103. Bb1 Kb7 104. Kf1 Ka8 105. Kf2 Kb7 106. Ke1 Ka8 107. Kd1 Kb7 108. Kc1 Ka8 109. Ba2 Kb7 110. Kb1 Ka8 111. Ka1 Kb7 112. Bb1 Ka8 113. Ka2 Kb7 114. Ka3 Ka8 115. Ka4 Kb7. 116. Ka5 h3 117. Ka4 Ka8 118. Ka3 Kb7 119. Ka2 Ka8 120. Ka1 Kb7 121. Ba2 Ka8 122. Kb1 Kb7 123. Kc1 Ka8 124. Kd1 Kb7 125. Ke1 Ka8 126. Bb1 Kb7 127. Kf1 Ka8 128. Kf2 Kb7 129. Ke1 Ka8 130. Kd1 Kb7 131. Kc1 Ka8 132. Ba2 Kb7 133. Kb1 Ka8 134. Ka1 Kb7 135. Bb1 Ka8 136. Ka2 Kb7 137. Ka3 Ka8 138. Ka4 Kb7 139. Ka5 h2 140. Ka4 Ka8 141. Ka3 Kb7 142. Ka2 Ka8 143. Ka1 Kb7 144. Ba2 Ka8 145. Kb1 Kb7 146. Kc1 Ka8 147. Kd1 Kb7 148. Ke1 Ka8 149. Bb1 Kb7 150. Kf1 Ka8 151. Kf2 Kb7 152. Ke1 Ka8 153. Kd1 Kb7 154. Kc1 Ka8 155. Ba2 Kb7 156. Kb1 Ka8 157. Ka1 Kb7 158. Bb1 Ka8 159. Ka2 Kb7 160. Ka3 Ka8 161. Ka4 Kb7 162. Ka5 h6 163. Ka4 Ka8 164. Ka3 Kb7 165. Ka2 Ka8 166. Ka1 Kb7 167. Ba2 Ka8 168. Kb1 Kb7 169. Kc1 Ka8 170. Kd1 Kb7 171. Ke1 Ka8 172. Bb1 Kb7 173. Kf1 Ka8 174. Kf2 Kb7 175. Ke1 Ka8 176. Kd1 Kb7 177. Kc1 Ka8 178. Ba2 Kb7 179. Kb1 Ka8 180. Ka1 Kb7 181. Bb1 Ka8 182. Ka2 Kb7 183. Ka3 Ka8 184. Ka4 Kb7 185. Ka5 h5 186. Ka4 Ka8 187. Ka3 Kb7 188. Ka2 Ka8 189. Ka1 Kb7 190. Ba2 Ka8 191. Kb1 Kb7 192. Kc1 Ka8 193. Kd1 Kb7 194. Ke1 Ka8 195. Bb1 Kb7 196. Kf1 Ka8 197. Kf2 Kb7 198. Ke1 Ka8 199. Kd1 Kb7 200. Kc1 Ka8 201. Ba2 Kb7 202. Kb1 Ka8 203. Ka1 Kb7 204. Bb1 Ka8 205. Ka2 Kb7 206. Ka3 Ka8 207. Ka4 Kb7 208. Ka5 h4 209. Ka4 Ka8 210. Ka3 Kb7 211. Ka2 Ka8 212. Ka1 Kb7 213. Ba2 Ka8 214. Kb1 Kb7 215. Kc1 Ka8 216. Kd1 Kb7 217. Ke1 Ka8 218. Bb1 Kb7 219. Kf1 Ka8 220. Kf2 Kb7 221. Ke1 Ka8 222. Kd1 Kb7 223. Kc1 Ka8 224. Ba2 Kb7 225. Kb1 Ka8 226. Ka1 Kb7 227. Bb1 Ka8 228. Ka2 Kb7 229. Ka3 Ka8 230. Ka4 Kb7 231. Ka5 h3 232. Ka4 Ka8 233. Ka3 Kb7 234. Ka2 Ka8 235. Ka1 Kb7 236. Ba2 Ka8 237. Kb1 Kb7 238. Kc1 Ka8 239. Kd1 Kb7 240. Ke1 Ka8 241. Bb1 Kb7 242. Kf1 Ka8 243. Kf2 Kb7 244. Ke1 Ka8 245. Kd1 Kb7 246. Kc1 Ka8 247. Ba2 Kb7 248. Kb1 Ka8 249. Ka1 Kb7 250. Bb1 Ka8 251. Ka2 Kb7 252. Ka3 Ka8 253. Ka4 Kb7 254. Ka5 Kc8 255. Ka6 Kd8 256. b7 Nd7 257. Bxf3 h1=Q 258. Bxh1 d3 259. cxd3 f3 260. Bxf3 Ke7 261. b8=Q Nxb8+ 262. Bxb8 c2 263. Bxc2 Ke6 264. b6 Kf6 265. b7 Ke6 266. d4 h2 267. Bxh2 f4 268. b8=Q Kf7 269. Bxf4  Kg7 270. Bh5 Kf6 271. Qe5#

```

In regards to the longest known correct checkmate in an illegal position that uses just pieces from the chess box, as Blathy repurposed the the light squared bishop onto a dark square.

Note-Althogh Blathy is known to have composed to slightly longer dualed, illegal mate in 292 moves, that problem is **cooked,** meaning it is incorrect and has a shorter solution although I still searching for an exact mention of where in the problem are the moves that Blathy missed in his analysis.

```
[Title "Otto Blathy, Weihnachtsgrüße 12/1929, Mate In 290"]
[FEN "bBrb1B2/P1n1r2p/1Kp1Pb1p/2pk1P1p/5P2/1P2pP2/1pP1P3/1R4n1 w - - 0 1"]

1. Rd1+ Bd4 2. c4+ Kd6 3. Rxg1 Bc3 4. Rd1+ Bd4 5. Ka5 Bb7 6. Ka4 Ba8 7. Ka3 Bb7 8. Ka2 Ba8 9. Kb1 Bb7 10. Kc2 Ba8 11. Kd3 Bb7 12. Re1 Ba8 13. Rf1 Bb7 14. Rd1 Ba8 15. Kc2 Bb7 16. Kb1 Ba8 17. Ka2 Bb7 18. Ka3 Ba8 19. Ka4 Bb7 20. Ka5 Ba8 21. Kb6 h4 22. Ka5 Bb7 23. Ka4 Ba8 24. Ka3 Bb7 25. Ka2 Ba8 26. Kb1 Bb7 27. Kc2 Ba8 28. Kd3 Bb7 29. Rf1 Ba8 30. Re1 Bb7 31. Rd1 Ba8 32. Kc2 Bb7 33. Kb1 Ba8 34. Ka2 Bb7 35. Ka3 Ba8 36. Ka4 Bb7 37. Ka5 Ba8 38. Kb6 h3 39. Ka5 Bb7 40. Ka4 Ba8 41. Ka3 Bb7 42. Ka2 Ba8 43. Kb1 Bb7 44. Kc2 Ba8 45. Kd3 Bb7 46. Rf1 Ba8 47. Re1 Bb7 48. Rd1 Ba8 49. Kc2 Bb7 50. Kb1 Ba8 51. Ka2 Bb7 52. Ka3 Ba8 53. Ka4 Bb7 54. Ka5 Ba8 55. Kb6 h2 56. Ka5 Bb7 57. Ka4 Ba8 58. Ka3 Bb7 59. Ka2 Ba8 60. Kb1 Bb7 61. Kc2 Ba8 62. Kd3 Bb7 63. Rf1 Ba8 64. Re1 Bb7 65. Rd1 Ba8 66. Kc2 Bb7 67. Kb1 Ba8 68. Ka2 Bb7 69. Ka3 Ba8 70. Ka4 Bb7 71. Ka5 Ba8 72. Kb6 h5 73. Ka5 Bb7 74. Ka4 Ba8 75. Ka3 Bb7 76. Ka2 Ba8 77. Kb1 Bb7 78. Kc2 Ba8 79. Kd3 Bb7 80. Rf1 Ba8 81. Re1 Bb7 82. Rd1 Ba8 83. Kc2 Bb7 84. Kb1 Ba8 85. Ka2 Bb7 86. Ka3 Ba8 87. Ka4 Bb7 88. Ka5 Ba8 89. Kb6 h4 90. Ka5 Bb7 91. Ka4 Ba8 92. Ka3 Bb7 93. Ka2 Ba8 94. Kb1 Bb7 95. Kc2 Ba8 96. Kd3 Bb7 97. Rf1 Ba8 98. Re1 Bb7 99. Rd1 Ba8 100. Kc2 Bb7 101. Kb1 Ba8 102. Ka2 Bb7 103. Ka3 Ba8 104. Ka4 Bb7 105. Ka5 Ba8 106. Kb6 h3 107. Ka5 Bb7 108. Ka4 Ba8 109. Ka3 Bb7 110. Ka2 Ba8 111. Kb1 Bb7 112. Kc2 Ba8 113. Kd3 Bb7 114. Rf1 Ba8 115. Re1 Bb7 116. Rd1 Ba8 117. Kc2 Bb7 118. Kb1 Ba8 119. Ka2 Bb7 120. Ka3 Ba8 121. Ka4 Bb7 122. Ka5 Ba8 123. Kb6 h6 124. Ka5 Bb7 125. Ka4 Ba8 126. Ka3 Bb7 127. Ka2 Ba8 128. Kb1 Bb7 129. Kc2 Ba8 130. Kd3 Bb7  131. Rf1 Ba8 132. Re1 Bb7 133. Rd1 Ba8 134. Kc2 Bb7 135. Kb1 Ba8 136. Ka2 Bb7 137. Ka3 Ba8 138. Ka4 Bb7 139. Ka5 Ba8 140. Kb6 h5 141. Ka5 Bb7 142. Ka4 Ba8 143. Ka3 Bb7 144. Ka2 Ba8 145. Kb1 Bb7 146. Kc2 Ba8 147. Kd3 Bb7 148. Rf1 Ba8 149. Re1 Bb7 150. Rd1 Ba8 151. Kc2 Bb7 152. Kb1 Ba8 153. Ka2 Bb7 154. Ka3 Ba8 155. Ka4 Bb7 156. Ka5 Ba8 157. Kb6 h4 158. Ka5 Bb7 159. Ka4 Ba8 160. Ka3 Bb7 161. Ka2 Ba8 162. Kb1 Bb7 163. Kc2 Ba8 164. Kd3 Bb7 165. Rf1 Ba8 166. Re1 Bb7 167. Rd1 Ba8 168. Kc2 Bb7 169. Kb1 Ba8 170. Ka2 Bb7 171. Ka3 Ba8 172. Ka4 Bb7 173. Ka5 Ba8 174. Kb6 h1=Q 175. Rxh1 Bg7 176. Rd1+ Bd4 177. Ka5 Bb7 178. Ka4 Ba8 179. Ka3 Bb7 180. Ka2 Ba8 181. Kb1 Bb7 182. Kc2 Ba8 183. Kd3 Bb7 184. Rf1 Ba8 185. Re1 Bb7 186. Rd1 Ba8 187. Kc2 Bb7 188. Kb1 Ba8 189. Ka2 Bb7 190. Ka3 Ba8 191. Ka4 Bb7 192. Ka5 Ba8 193. Kb6 h2 194. Ka5 Bb7 195. Ka4 Ba8 196. Ka3 Bb7 197. Ka2 Ba8 198. Kb1 Bb7 199. Kc2 Ba8 200. Kd3 Bb7 201. Rf1 Ba8 202. Re1 Bb7 203. Rd1 Ba8 204. Kc2 Bb7 205. Kb1 Ba8 206. Ka2 Bb7 207. Ka3 Ba8 208. Ka4 Bb7 209. Ka5 Ba8 210. Kb6 h3 211. Ka5 Bb7 212. Ka4 Ba8 213. Ka3 Bb7 214. Ka2 Ba8 215. Kb1 Bb7 216. Kc2 Ba8 217. Kd3 Bb7 218. Rf1 Ba8 219. Re1 Bb7 220. Rd1 Ba8 221. Kc2 Bb7 222. Kb1 Ba8 223. Ka2 Bb7 224. Ka3 Ba8 225. Ka4 Bb7 226. Ka5 Ba8 227. Kb6 h1=Q 228. Rxh1 Bg7 229. Rd1+ Bd4 230. Ka5 Bb7 231. Ka4 Ba8 232. Ka3 Bb7 233. Ka2 Ba8 234. Kb1 Bb7 235. Kc2 Ba8 236. Kd3 Bb7 237. Rf1 Ba8 238. Re1 Bb7 239. Rd1 Ba8 240. Kc2 Bb7 241. Kb1 Ba8 242. Ka2 Bb7 243. Ka3 Ba8 244. Ka4 Bb7 245. Ka5 Ba8 246. Kb6 h2 247. Ka5 Bb7 248. Ka4 Ba8 249. Ka3 Bb7 250. Ka2 Ba8 251. Kb1 Bb7 252. Kc2 Ba8 253. Kd3 Bb7 254. Rf1 Ba8 255. Re1 Bb7 256. Rd1 Ba8 257. Kc2 Bb7 258. Kb1 Ba8 259. Ka2 Bb7 260. Ka3 Ba8 261. Ka4 Bb7 262. Ka5 Ba8 263. Kb6 h1=Q 264. Rxh1 Bg7 265. Rd1+ Bd4 266. Ka5 Bb7 267. Ka4 Ba8 268. Ka3 Bb7 269. Ka2 Ba8 270. Kb1 Bb7 271. Kc2 Ba8 272. Kd3 Bb7 273. Rf1 Ba8 274. Re1 Bb7 275. Rd1 Ba8 276. Kc2 Bb7 277. Kb1 Ba8 278. Ka2 Bb7 279. Ka3 Ba8 280. Ka4 Bb7 281. Ka5 Ba8 282. Kb6 Bb7 283. Kxb7 b1=Q 284. Rxb1 Be5 285. Rd1+ Bd4 286. Rxd4+ cxd4 287. Kb6 d3 288. a8=Q Rxb8+ 289. Qxb8 dxe2 290. Qxd8#

```

Lastly, if you allow any amount of illegal material, with no first/last rank pawns and one king per side of course, here is a mate in 415 that is an extension of Blathy's above mate in 290.

```
 [FEN "bBrb1B2/P1n1r1bp/pKp1P2p/2pk1P1p/5P1p/1P2pP1p/1pP1P2p/1R5n w - - 0 1"]

1. Rd1+ Bd4 2. c4+ Kd6 3. Rxh1 Bc3 4. Rd1+ Bd4 5. Ka5 Bb7 6. Ka4 Ba8 7. Ka3 Bb7 8. Ka2 Ba8 9. Kb1 Bb7 10. Kc2 Ba8 11. Kd3 Bb7 12. Rh1 Ba8 13. Rf1 Bb7 14. Rd1 Ba8 15. Kc2 Bb7 16. Kb1 Ba8 17. Ka2 Bb7 18. Ka3 Ba8 19. Ka4 Bb7 20. Ka5 Ba8 21. Kb6 h1=Q 22. Rxh1 Bc3 23. Rd1+ Bd4 24. Ka5 Bb7 25. Ka4 Ba8 26. Ka3 Bb7 27. Ka2 Ba8 28. Kb1 Bb7 29. Kc2 Ba8 30. Kd3 Bb7 31. Rh1 Ba8 32. Rf1 Bb7 33. Rd1 Ba8 34. Kc2 Bb7 35. Kb1 Ba8 36. Ka2 Bb7 37. Ka3 Ba8 38. Ka4 Bb7 39. Ka5 Ba8 40. Kb6 h2 41. Ka5 Bb7 42. Ka4 Ba8 43. Ka3 Bb7 44. Ka2 Ba8 45. Kb1 Bb7 46. Kc2 Ba8 47. Kd3 Bb7 48. Rh1 Ba8 49. Rf1 Bb7 50. Rd1 Ba8 51. Kc2 Bb7 52. Kb1 Ba8 53. Ka2 Bb7 54. Ka3 Ba8 55. Ka4 Bb7 56. Ka5 Ba8 57. Kb6 h3 58. Ka5 Bb7 59. Ka4 Ba8 60. Ka3 Bb7 61. Ka2 Ba8 62. Kb1 Bb7 63. Kc2 Ba8 64. Kd3 Bb7 65. Rh1 Ba8 66. Rf1 Bb7 67. Rd1 Ba8 68. Kc2 Bb7 69. Kb1 Ba8 70. Ka2 Bb7 71. Ka3 Ba8 72. Ka4 Bb7 73. Ka5 Ba8 74. Kb6 h4 75. Ka5 Bb7 76. Ka4 Ba8 77. Ka3 Bb7 78. Ka2 Ba8 79. Kb1 Bb7 80. Kc2 Ba8 81. Kd3 Bb7 82. Rh1 Ba8 83. Rf1 Bb7 84. Rd1 Ba8 85. Kc2 Bb7 86. Kb1 Ba8 87. Ka2 Bb7 88. Ka3 Ba8 89. Ka4 Bb7 90. Ka5 Ba8 91. Kb6 h5 92. Ka5 Bb7 93. Ka4 Ba8 94. Ka3 Bb7 95. Ka2 Ba8 96. Kb1 Bb7 97. Kc2 Ba8 98. Kd3 Bb7 99. Rh1 Ba8 100. Rf1 Bb7 101. Rd1 Ba8 102. Kc2 Bb7 103. Kb1 Ba8 104. Ka2 Bb7 105. Ka3 Ba8 106. Ka4 Bb7 107. Ka5 Ba8 108. Kb6 h6 109. Ka5 Bb7 110. Ka4 Ba8 111. Ka3 Bb7 112. Ka2 Ba8  113. Kb1 Bb7 114. Kc2 Ba8 115. Kd3 Bb7 116. Rh1 Ba8 117. Rf1 Bb7 118. Rd1 Ba8 119. Kc2 Bb7 120. Kb1 Ba8 121. Ka2 Bb7 122. Ka3 Ba8 123. Ka4 Bb7 124. Ka5 Ba8 125. Kb6 h1=Q 126. Rxh1 Bc3 127. Rd1+ Bd4 128. Ka5 Bb7 129. Ka4 Ba8 130. Ka3 Bb7 131. Ka2 Ba8 132. Kb1 Bb7 133. Kc2 Ba8 134. Kd3 Bb7 135. Rh1 Ba8 136. Rf1 Bb7 137. Rd1 Ba8 138. Kc2 Bb7 139. Kb1 Ba8 140. Ka2 Bb7 141. Ka3 Ba8 142. Ka4 Bb7 143. Ka5 Ba8 144. Kb6 h2 145. Ka5 Bb7 146. Ka4 Ba8 147. Ka3 Bb7 148. Ka2 Ba8 149. Kb1 Bb7 150. Kc2 Ba8 151. Kd3 Bb7 152. Rh1 Ba8 153. Rf1 Bb7 154. Rd1 Ba8 155. Kc2 Bb7 156. Kb1 Ba8 157. Ka2 Bb7 158. Ka3 Ba8 159. Ka4 Bb7 160. Ka5 Ba8 161. Kb6 h3 162. Ka5 Bb7 163. Ka4 Ba8 164. Ka3 Bb7 165. Ka2 Ba8 166. Kb1 Bb7 167. Kc2 Ba8 168. Kd3 Bb7 169. Rh1 Ba8 170. Rf1 Bb7 171. Rd1 Ba8 172. Kc2 Bb7 173. Kb1 Ba8 174. Ka2 Bb7 175. Ka3 Ba8 176. Ka4 Bb7 177. Ka5 Ba8 178. Kb6 h4 179. Ka5 Bb7 180. Ka4 Ba8 181. Ka3 Bb7 182. Ka2 Ba8 183. Kb1 Bb7 184. Kc2 Ba8 185. Kd3 Bb7 186. Rh1 Ba8 187. Rf1 Bb7 188. Rd1 Ba8 189. Kc2 Bb7 190. Kb1 Ba8 191. Ka2 Bb7 192. Ka3 Ba8 193. Ka4 Bb7 194. Ka5 Ba8 195. Kb6 h5 196. Ka5 Bb7 197. Ka4 Ba8 198. Ka3 Bb7 199. Ka2 Ba8 200. Kb1 Bb7 201. Kc2 Ba8 202. Kd3 Bb7 203. Rh1 Ba8 204. Rf1 Bb7 205. Rd1 Ba8 206. Kc2 Bb7 207. Kb1 Ba8 208. Ka2 Bb7 209. Ka3 Ba8 210. Ka4 Bb7 211. Ka5 Ba8 212. Kb6 h1=Q 213. Rxh1 Bc3 214. Rd1+ Bd4 215. Ka5 Bb7 216. Ka4 Ba8 217. Ka3 Bb7 218. Ka2 Ba8 219. Kb1 Bb7 220. Kc2 Ba8 221. Kd3 Bb7 222. Rh1 Ba8 223. Rf1 Bb7 224. Rd1 Ba8 225. Kc2 Bb7 226. Kb1 Ba8 227. Ka2 Bb7 228. Ka3 Ba8 229. Ka4 Bb7 230. Ka5 Ba8 231. Kb6 h2 232. Ka5 Bb7 233. Ka4 Ba8 234. Ka3 Bb7 235. Ka2 Ba8 236. Kb1 Bb7 237. Kc2 Ba8 238. Kd3 Bb7 239. Rh1 Ba8 240. Rf1 Bb7 241. Rd1 Ba8 242. Kc2 Bb7 243. Kb1 Ba8 244. Ka2 Bb7 245. Ka3 Ba8 246. Ka4 Bb7 247. Ka5 Ba8 248. Kb6 h3 249. Ka5 Bb7 250. Ka4 Ba8 251. Ka3 Bb7 252. Ka2 Ba8 253. Kb1 Bb7 254. Kc2 Ba8 255. Kd3 Bb7 256. Rh1 Ba8 257. Rf1 Bb7 258. Rd1 Ba8 259. Kc2 Bb7 260. Kb1 Ba8 261. Ka2 Bb7 262. Ka3 Ba8 263. Ka4 Bb7 264. Ka5 Ba8 265. Kb6 h4 266. Ka5 Bb7 267. Ka4 Ba8 268. Ka3 Bb7 269. Ka2 Ba8 270. Kb1 Bb7 271. Kc2 Ba8 272. Kd3 Bb7 273. Rh1 Ba8 274. Rf1 Bb7 275. Rd1 Ba8 276. Kc2 Bb7 277. Kb1 Ba8 278. Ka2 Bb7 279. Ka3 Ba8 280. Ka4 Bb7 281. Ka5 Ba8 282. Kb6 h1=Q 283. Rxh1 Bc3 284. Rd1+ Bd4 285. Ka5 Bb7 286. Ka4 Ba8 287. Ka3 Bb7 288. Ka2 Ba8 289. Kb1 Bb7 290. Kc2 Ba8 291. Kd3 Bb7 292. Rh1 Ba8 293. Rf1 Bb7 294. Rd1 Ba8 295. Kc2 Bb7 296. Kb1 Ba8 297. Ka2 Bb7 298. Ka3 Ba8 299. Ka4 Bb7 300. Ka5 Ba8 301. Kb6 h2 302. Ka5 Bb7 303. Ka4 Ba8 304. Ka3 Bb7 305. Ka2 Ba8 306. Kb1 Bb7 307. Kc2 Ba8 308. Kd3 Bb7 309. Rh1 Ba8 310. Rf1 Bb7 311. Rd1 Ba8 312. Kc2 Bb7 313. Kb1 Ba8 314. Ka2 Bb7 315. Ka3 Ba8 316. Ka4 Bb7 317. Ka5 Ba8 318. Kb6 h3 319. Ka5 Bb7 320. Ka4 Ba8 321. Ka3 Bb7 322. Ka2 Ba8 323. Kb1 Bb7 324. Kc2 Ba8 325. Kd3 Bb7 326. Rh1 Ba8 327. Rf1 Bb7 328. Rd1 Ba8 329. Kc2 Bb7 330. Kb1 Ba8 331. Ka2 Bb7 332. Ka3 Ba8 333. Ka4 Bb7 334. Ka5 Ba8 335. Kb6 h1=Q 336. Rxh1 Bc3 337. Rd1+ Bd4 338. Ka5 Bb7 339. Ka4 Ba8 340. Ka3 Bb7 341. Ka2 Ba8 342. Kb1 Bb7 343. Kc2 Ba8 344. Kd3 Bb7 345. Rh1 Ba8 346. Rf1 Bb7 347. Rd1 Ba8 348. Kc2 Bb7 349. Kb1 Ba8 350. Ka2 Bb7 351. Ka3 Ba8 352. Ka4 Bb7 353. Ka5 Ba8 354. Kb6 h2 355. Ka5 Bb7 356. Ka4 Ba8 357. Ka3 Bb7 358. Ka2 Ba8 359. Kb1 Bb7 360. Kc2 Ba8 361. Kd3 Bb7 362. Rh1 Ba8 363. Rf1 Bb7 364. Rd1 Ba8 365. Kc2 Bb7 366. Kb1 Ba8 367. Ka2 Bb7 368. Ka3 Ba8 369. Ka4 Bb7 370. Ka5 Ba8 371. Kb6 h1=Q 372. Rxh1 Bc3 373. Rd1+ Bd4 374. Ka5 Bb7 375. Ka4 Ba8 376. Ka3 Bb7 377. Ka2 Ba8 378. Kb1 Bb7 379. Kc2 Ba8 380. Kd3 Bb7 381. Rh1 Ba8 382. Rf1 Bb7 383. Rd1 Ba8 384. Kc2 Bb7 385. Kb1 Ba8 386. Ka2 Bb7 387. Ka3 Ba8 388. Ka4 Bb7 389. Ka5 Ba8 390. Kb6 a5 391. Kxa5 Bb7 392. Ka4 Ba8 393. Ka3 Bb7 394. Ka2 Ba8 395. Kb1 Bb7 396. Kc2 Ba8 397. Kd3 Bb7 398. Rh1 Ba8 399. Rf1 Bb7 400. Rd1 Ba8 401. Kc2 Bb7 402. Kb1 Ba8 403. Ka2 Bb7 404. Ka3 Ba8 405. Ka4 Bb7 406. Ka5 Ba8 407. Kb6 Bb7 408. Kxb7 b1=Q 409. Rxb1 Be5 410. Rd1+ Bd4 411. Rxd4+ cxd4 412. Kb6 d3 413. a8=Q Rxb8+ 414. Qxb8 d2 415. Qxd8#

```

---
Tags: checkmate, problems, composing
---


title: Plans in the Scandinavian Defence

text:
# Question
Title: Plans in the Scandinavian Defence
I'm playing the Scandinavian Defence with 3...Qd8 a lot and I really like that opening. But I can't seem to find the right plan. I just develop my pieces towards the center (I don't fianchetto my bishop on g7) and then hope my opponent blunders. Could you please tell me on what I can improve? I'm a 1200 FIDE rated player.

I have already searched the web but the only thing I came up with, was that Scandinavian Defence is considered bad at high level.

I also saw some master games but that doesn't really help as they all play 3...Qa5.

# Answer
If you really must, because your friend bet a wager that he can beat you as black in this position, here are the imbalances, concrete and possible, that you must look out for (as white):

```
[FEN ""]

1.e4 d5 2. exd5 Qxd5 3. Nc3 Qd8

```
* Black's open d-file
* Active LSB
* Kingside pawn majority

Still, this is not without its weaknesses:

* A delay in development. White can safely continue with d4, Be3, Qd2, O-O-O.
* Black's reduced control of the squares on the e-file. Castle long and prompt to push his f-pawn somehow, followed by a minority attack g2-g4 (or g2-g4-g5).
* Black's reduced control of the squares on the c-file. If black castles long, or the situation somehow else warrants it, break open the c-file, create an outpost on the c4-c5 square, and move a knight, bishop, or rook to this square where b7-b6 or b7-b5 has to happen. Now you'll have a new, but weakened structure to attack.

Black will play to nullify white's knights with ...Bg4 (if Nf3), ...e6, ...Bc5, Ne7, and O-O, finally obtaining a solid position. If white castles short, black can launch a minority attack, creating holes which his knights can then infiltrate. He can place pressure on the d-pawn by restricting its advance, playing c7-c6, ...Rd8, and ...Nd5. If white plays c4, then the d-pawn has become weakened and serves as a target.
> 8 votes

# Answer
I would say that the only obvious target for black (meaning a plan that's almost build into the opening) is applying pressure to the white d pawn, assuming white does play d4. Then of course he should try to break with either c5 or e5.

I can recommend checking out IM John Bartholomew, he's got a Youtube channel and he's a huge fan of the Scandi Qd8 line, I understand he's also got some tutorial on the line.
> 4 votes

# Answer
Fundamentally speaking, Black's position has no weaknesses, but is behind in development. Theory says if Black can solve his development, he will be equal. Magnus Carlsen has played this position as black (vs Fabiano, Tromsoe Ol, 2014, 0-1, 50), as have many other GMs, the likely reason because black has no weaknesses to speak of, and can draw equal. The Scandanavian Defense is deceptively resilient. So, in general, find good squares for your pieces. Black will play e6, complete his development and look for play where the game leads him. Since he has no weaknesses, White will be short of good targets. Since it is so early in the game, to elucidate on any plan this early is folly, as you have to take into account White's play and ideas. At 1200 level, mistakes will be made. Don't make the last one!
> 3 votes

# Answer
Your main plan is to fianchetto, Ng8-h6-f5 to put pressure on the d4-pawn. Then, you can attempt to blockade it with the other knight, and then to put your rooks on the d-file. Basically, the strategic plan is to pressure White's d-pawn.
> 1 votes

---
Tags: opening, planning, scandinavian-defense
---


# Question
Title: Did Leela Zero miss a win in this position?
Did Leela Zero miss a win in this position from game 106 of the Computer Chess Championship, on move 83 with White to move?

```
[FEN "8/2p1r3/2P4k/1P1pB2p/K2NbP1R/P5r1/8/8 w - - 0 1"]

```

Here, Leela Zero played Bxc7? for their 83rd move. I went deep to analyze the position at 34/91 with Houdini 6.02 for one hour, and the game reached a position with White having a rook, bishop, knight and pawn against Black's two rooks. I analyzed it again starting from there, and either White will increase his positional advantage or Black will be forced into simplifying into a tablebase win for White. Is all this true? Rh2 was the winning move according to Houdini 6.02.

# Answer
For what that's worth, Stockfish 11 gives

* **Rh2** as **+2.6**
* **Kb4** as **+2.2**
* **Bxc7** as **+0.6**
* other moves as **0.0**

on my machine at depth **45** (will be updating this answer while it digs deeper). Rh2 and Kb4 occasionally switch positions as #1 and #2, so it's still unclear which one of these is truly best. Bxc7 surely isn't, however, at least if you believe Stockfish.

One important note: The top evaluation score has hovered between +2.0 and +2.6 since depth 15. Apparently, Stockfish has not found a way to substantially improve White's position (let alone win) in the last 30 plies. It's still possible that the game will end in a fortress situation with perfect play, and then Leela would in fact not have missed a win (despite having played a suboptimal move).

---

Edit:

At depth **54**, it's

* **Rh2** as **+3.9**
* **Kb4** as **+2.2**
* **Bxc7** as **+0.1**
* other moves as **0.0**

Still not fully conclusive, but we're starting to get somewhere.

In any case, Bxc7 was certainly not the most optimal move that Leela could have played.
> 2 votes

# Answer
Houdini is severely weaker than LC0. I have seen their evaulations of positions, such as in the Salvio Gambit, which Houdini evaluates as only slightly worse for White(clearly not true), where LC0 states that Black has a sizeable advantage.

Thus, it is more likely that Leela had played the best move. We cannot know for sure until we prove a forced win for White in N moves.
> 1 votes

# Answer
Dunno but BxP on c7 looks like a winner to me.

Whether black captures with the rook or not the b pawn marches quickly to become a Q
> 0 votes

---
Tags: analysis, endgame, stockfish, computer-chess, leela
---


# Question
Title: What is the maximum number of checked squares on a board that delivers checkmate without a draw?
I’ve long dreamt of delivering a “super checkmate”.

Imagine that as his dying wish, when in checkmate, the king can magically transport himself to any open square on the board.

What is the board configuration which minimizes the number of squares he can safely teleport to? Is it possible for there to be no safe squares, so the king’s wish can’t save him?

Of course, we can imagine somehow the opponent promoted all his pawns to queens along the back rank, so every square is covered, but this configuration is not achievable without having drawn along the way (I believe; but prove me wrong!).

So I’m looking for a practical configuration that can be achieved naturally where the last move is checkmate.

Bonus points for each square that is under attack more than once.

# Answer
Any position with roaming kings is hardly "natural," so I believe you mean if such a position is legal. If I understand correctly, kings may only attempt teleportation if checkmated; otherwise, it would be nigh impossible to checkmate.

Firstly, it *is* possible to promote eight queens and checkmate without drawing.

```
[FEN "8/PPPPPPPP/8/8/8/K7/8/1k6 w - - 0 1"]

1. c8=Q Ka1 2. a8=Q Kb1 3. d8=Q Ka1 4. e8=Q Kb1 5. f8=Q Ka1 6. h8=Q Kb1 7. b8=Q+ Ka1 8. g8=Q#

```

This effect may also be achieved by utilizing White's eight officers. I recall this problem by Josef Kling. The stipulation is "White checkmates in 14 moves but only after attacking all 64 squares." I would suppose that this position is more "natural" than one with eight queens.

```
[Title "Josef Kling, The Chess Player's Companion 1849, 'Fancy Sketch'"]
[FEN "4k3/8/8/8/8/8/8/RNBQKBNR w - - 0 1"]

1. Qd6 Kf7 2. Rh8 Kg7 3. Bb2+ Kf7 4. Qa6 Ke7 5. Bh3 Kf7 6. Ke2 Ke7 7. Kd3 Kf7 8. Bd4 Ke7 9. Nd2 Kf7 10. Ne2 Ke7 11. Rg1 Kf7 12. Nc3 Ke7 13. Nd5+ Kf7 14. Be6#

```

(On a technical note, only 63 squares can actually be attacked and one occupied, but Kling knew this and 64 sounds better on paper. I also presume kings cannot teleport to occupied squares.)
> 14 votes

---
Tags: checkmate, problems
---


title: French defense plans

text:
# Question
Title: French defense plans
I'm working with my 1300 USCF kid on his opening repertoire. In the French defense, I have a few questions/problems I'm trying to resolve:

1) In many of the closed lines (after e5) we go after placing a knight on f5. Usually we go at it with ..h5, ..Nh6, ...Nf5. a) Sometimes people take the knight once it reaches h6 and we recapture with the rook. I struggle for a good plan after that, especially since the rooks are disconnected. b) When the knight does get to f5 it sometimes gets challenged by the white (light squared) bishop. The question is whether to reinforce this f5 knight with g6 and allow the capture, recapturing with gxf5. We try to play on the open g-file. I haven't been getting good practical results and wonder if I've got this wrong.

2) This question pertains to the advance variation. I've suggested using a quick ..c5, ..Qb6, ..Bd7, ..Bb5 to swap off the bad bishop. In this line we don't have the french Qside pawn storm at first. Moreover, I've been telling my son that if white breaks the tension with dxc5 we can recapture with ..Bxc5 which I thought was a "French dream". But recently in this "dream position", I've been hit with b4 and a queenside pawn storm initiative. Connected with 1a) above I've been getting bad games (no black queenside pawnstorm, and no Nf5 post). I'm wondering if there's a simple thing to do to create some black queen side space when the Queen is out front (perhaps ..a5)?

# Answer
I would suggest that you look up some theory in the French defense if you're planning on using it. What we seem to have here is a complete home brew.

For example, playing ...h5 before playing ...Nh6 is very uncommon. One of the reasons is that playing h5 as black actually makes Nh6 harder to play for black, as Bxh6 cannot really be answered with gxh6, as the h5 pawn becomes very weak. Thus black is encouraged to play Rxh6, which isn't ideal. If you want to play Nh6 in the advance variation, I suggest you play it without playing h5 first. You do not have to worry much about Bxh6 from white, as that makes b2 harder to defend, and gxh6 doesn't really give black many problems.

More importantly, if you are afraid of playing with the light squared bishop as black in the french, then the opening is not worth playing at all. I think that you may be underestimating the potential of that bishop, if all you want to do with it is trading it. A French player has to be able to play with the light square bishop as black to be successful in the long run. In essence, it's not worth the trouble to trade off the "bad" bishop.
> 3 votes

# Answer
> 1) In many of the closed lines (after e5) we go after placing a knight on f5. Usually we go at it with ..h5, ..Nh6, ...Nf5.

This is not a good plan. I'm curious as to where you got it from.

The problem is that by the nature of the pawn structure (white pawns on d4, e5, black pawns on e6, d5 and maybe c5) white has a natural attack on the king side and black more on the queen side. These king side moves of yours are if anything helping white.

You should be trying to attack the white pawn chain, either with c5 to attack d4 or f6 to attack e5. If you play f6 at some stage then you will have much better chances of king side activity than your Nh6-f5 plan.

> 2) This question pertains to the advance variation. I've suggested using a quick ..c5, ..Qb6, ..Bd7, ..Bb5 to swap off the bad bishop

Qb6 and Bd7 are usually two different plans. Qb6 aims to put pressure on the pawns at d4 and b2. It is used in conjunction with c5 and Nc6. Bd7 is usually used in conjunction with Qc7 where the queen is pressuring the pawn on e5 and maybe lining up to control the c file after the exchange cd by black or dc by white in conjunction with Rc8 and maybe Nb4.

The more normal way of trying to swap off the bad bishop is via b6 and Ba6 while the knight is still on b8. It's not a great plan and not one which I've ever tried because the knight is misplaced on a6 (should be on c6) from where it can exert no pressure whatsoever on white's pawns on d4 and e5.
> 0 votes

# Answer
The thematic ideas are these:

1. Attempt to trade off your c8-bishop or otherwise activate it.
2. Attack the d-pawn and gain active pieces.
3. Play on the queenside.
4. Play the breaks ...f6 and ...c5.
> 0 votes

---
Tags: opening, french-defense
---


# Question
Title: A castling variant-how would it change the game?
In chess, castling can't be done if the king or relevant rook have moved. How would the basic strategy of the game change if the king and rook could castle after moving? Also, how would the game change if the queen castle as well?

# Answer
In most cases, I'd imagine the queen wouldn't castle, as it would mean it would have a harder time getting out. The only useful case I can think of would be if you developed your bishop to e3 and "castled" queenside with your queen, putting it on c1, preparing for Bh6 to potentially trade off a fianchettoed bishop while also bringing your a1 rook to an active square. Being able to castle with your king or rook after you moved would change chess quite substantially, and it'd be difficult to quantify all the changes, but if I had to guess, kings would stay in the center longer and rooks would move around more in the middlegame.
> 3 votes

---
Tags: strategy, chess-variants, castling
---


title: King+Knight vs King+Pawn checkmate

text:
# Question
Title: King+Knight vs King+Pawn checkmate
How is it possible for a King and Knight to checkmate a King and Pawn? I've composed a working position, but I am not sure if this can occur through a series of moves.

# Answer
> 14 votes
In the general case K+N vs K+P is of course a draw - or a win for the pawn if it can promote unhindered.

There is however a famous construction were the knight can force a mate against a king stuck in front of its own well-advanced rook pawn:

```
[fen "8/3N4/8/8/8/p7/k7/2K5 w - - 0 1"]

1.Nc5 Ka1 2.Kc2 Ka2 3.Nd3 Ka1 4.Nc1 a2 5.Nb3#

```

There are many variations on that theme, the first such position being published by in the Bonus Socius before 1300.

# Answer
> 14 votes
Just for the record, the longest win in this endgame is 7 moves:

```
[FEN "8/8/8/8/p7/8/N7/k1K5 w - - 0 1"]

1. Nb4 a3 2. Nc2+ Ka2 3. Nd4 Ka1 4. Kc2 Ka2 5. Ne2 Ka1 6. Nc1 a2 7. Nb3#

```

The idea in this position (and other similar positions) is to stalemate the king in the corner; that forces a pawn move and when the pawn reaches a2, you'll need to have the knight positioned in such a way that it can immediately deliver mate.

Generally speaking, this only works (up to symmetry) if the pawn is on a3, the Black king on a1 or a2 and the White on c1 or c2 (otherwise, the king can escape) and the knight is both close enough (otherwise, Black can stalemate themselves) and has the right 'parity' - if Black to move loses, then White to move will only be able to draw. Likewise, if Black to move draws, then White to move wins. You can check a position in an online endgame tablebase like Sygyzy.

# Answer
> -2 votes
It is not possible for king+knight to *force* checkmate but a helpmate *is* possible.

Basically the pawn promotes to a bishop, the king moves to the opposite coloured square to the bishop with the bishop next to it and the opposing knight delivers checkmate with the king blocking off the two squares in front of the other king.

Like this:

```
[fen "KB6/8/kn6/8/8/8/8/8 w - - 0 1"]

```

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


# Question
Title: How are online tactic exercises ratings calculated?
There are several sites that give you a tactics rating changing while you solve or fail the exercises.

How do they calculate the problems rating?

Do they use engines to calculate the difficulty or strong players evaluate the difficulty exercise by exercise?

# Answer
> 15 votes
A typical way to do it is to treat puzzles the same as players and rate them based on whether they "win/lose" and the rating of the "opponent"

ChessTempo has a nice explanation here copied below:

> The rating system is inspired by an idea implemented at the Chess Tactics Server. CTS treats both problem solvers and the problems as opponents with their own ratings and adjusts their rating after problem completion (or failure) based on the Glicko ratings system.
>
> For blitz style games, time taken to solve problems is considered and an extra bonus is given for problems solved quickly. The solver gets a larger rating increase for problems solved quicker than one standard deviation from the average time taken for that problem. For problems solved faster than average but less than one standard deviation from the average, the normal Glicko based adjustment is made. If the problem is solved in slower than average time then the Glicko rating adjustment is reduced in proportion to how much slower than average the problem was solved. Very slow solutions may result in losing rating points, however you will never lose more points than you would if you simply got the problem wrong.
>
> When calculating the average time taken on a problem, only correct solutions are included, time taken from incorrect attempts are not used to calculate the average time a problem takes to solve.
>
> It is important to note that after a recent change to time handling in blitz mode, time taken after the first move is punished more severely than time taken before making your first move. The intention of this feature is to discourage 'incremental' guessing to try and solve a problem, rewarding users who sum up the situation before making their move sequence. Users who prefer to use an incremental approach may still do so, however their rating will be lower than users at the same level who think out the solutions first.
>
> Normal Glicko adjustments are made for standard ratings with no penalty for time taken. Problems marked incorrect cause the rating of that problem to increase and the solver's rating to decrease as dictated by normal Glicko rating calculations. Normal Glicko adjustments are also made for blitz problems that are marked wrong (i.e. the time taken in blitz is ignored when making rating adjustments for incorrect problems).

# Answer
> 0 votes
I believe that the tactics rating start on 100n rating. After solving puzzles, the change in rating decreases, so that eventually, you'll reach a rating which reflects your accuracy.

---
Tags: tactics, rating, online
---


title: Point assigned to move in Lucas Chess

text:
# Question
Title: Point assigned to move in Lucas Chess
I am a person trying to get better using Lucas chess. I am using the competitive mode and starting with the easiest engine. The tutor will suggest moves from time to time and will have a number associated with my move and the suggestion one (see below).

I have lost games taking the hints because I assumed largely positive numbers mean a stronger move. Are these pawn units and how is it calculated?

# Answer
> 2 votes
These numbers are the score given to the position by the engine. In your particular case (screenshot) these are the scores *after* the respective move is made. But of course you can also evaluate the current position in the same way.

Positive values mean that white is better, negative values that black is better, a value of zero means equal. So if you are playing black, you should aim for very small numbers (=negative numbers with large absolute value).

The actual numbers are made up based on many factors. The actual factors and the weight given to them will be different between engines, but all (decent) engines would give most weight to the material. And as you guessed right a value of 1 corresponds to one pawn (see your example where black has one pawn less and the evaluation is around +1).

Some other factors and a very simplified view of how they could be implemented on a computer are:

* piece activity; could evaluate the number of all possible moves
* king safety; number of defenders around the king
* control of the center; number of squares under attack in the center
* pawn structure; minus points for doubled pawns or for isolated pawns...

In my experience positions with evaluation between about -1 and +1 still have a good chance of ending in a draw (assuming best play) while starting from 1.5 or 2 the games have a decisive result (assuming best play).

# Answer
> 1 votes
The points are given by a chess engine. I believe Lucas uses the Stockfish engine.

In short, the engine scores your position approximately by the number of pawns. If you have 1.00, you would have an extra pawn advantage.

The magnitude indicates how strong or weak your position is. Positive means advantage for White, and negative translates to advantage for Black.

# Answer
> 0 votes
You probably are losing because you aren't reading the engine indications correctly. If you are playing White, the larger positive number is the better move, while if you are playing Black, then you want a 'large' negative number on the reading.

---
Tags: engines, analysis, chess-variants, point-value
---


# Question
Title: How to mathematically determine if king and pawn versus king endgame is a draw or a win?
I am aware of questions such as this one which discussed a method of determining if a king pawn vs king endgame is a draw or not. The accepted answer gave detailed guidelines but is not mathematically strict. I am asking the question again, but from a different angle.

If we label all the squares of the board as 1, 2, ..., 64 and we will use three numbers to denote the position of white king, black king, and white pawn, respectively. Let f be a function whose domain is a subset of {1,...,64}×{1,...,64}×{9,...,56}×{0,1} and whose range is {1/2,1}. Here × denotes the Cartesian product and the third set is {9,...,56} instead of {1,...,64} as it denotes the position of the white pawn. The fourth set {0,1} denotes whose turn it is; 0 for white and 1 for black. For the range, 1/2 means draw and 1 means win for white (assuming both sides only play the best moves possible). The actually domain is a subset of {1,...,64}×{1,...,64}×{9,...,56}×{0,1} instead of the entire set since no two or more pieces can occupy the same square and two kings cannot be adjacent to each other.

With the above definition, f is a function whose domain contains fewer than 64×64×48×2=393216 elements and whose range contains 2 elements. So it is possible (though may be difficult) to express f explicitly.

My question is: How to mathematically determine the output of the function f, given any input and therefore determine if a king and pawn vs king endgame is a draw or not?

In other words, I am looking for a way to find the value of f(x,y,z,w), where x denotes the position of the white king, y for the black king, z for the white pawn, w for whose turn it is and the output of f can only be 1/2 and 1.

# Answer
> 5 votes
You can do this (the space is, after all, finite) but it ends up being tedious, and is probably inferior to just looking it up in a tablebase.

Let's start with one of the most basic concepts in king and pawn endgames: the pawn square. White generally wins if Black is too far away to enter the square. We just need to convert this rule into simpler rules, and then convert those into your mathematical scheme.

If, with White to move, the White pawn is farther advanced than the Black king, White wins. If, with Black to move, the White pawn is 2 ranks farther advanced than the Black king, White wins.
So, if `floor(y/8) + w < floor(z/8)` then `f(x,y,z,w} = 1`.

If, with White to move, there are more files between the Black king and the pawn than there are ranks between the White pawn and the 8th rank, White wins. If, with Black to move, there are 2 more files between the Black king and the pawn than there are ranks between the White pawn and the 8th rank, White wins.
So, if `abs((y mod 8)-(z mod 8)) + w < (8-floor(z/8))` then `f(x,y,z,w} = 1`.

But we aren't done yet. If the pawn is on the second rank, it can go an extra square on its first move. But if Black has the move and is next to the pawn, he might be able to capture the pawn right away before it can move those 2 squares.
So, if `z` is in {9...16}, and `w = 0` or `(abs(z/8 - y/8 > 1)` or `abs((z mod 8) - (y mod 8) > 1)`, then if `((y mod 8)-(z mod 8)) + w+1 < (8-floor(z/8))` or `floor(y/8)+w+1 < floor(z/8)` then `f(x,y,z,w} = 1`.

But we still aren't done. There's an exception to the pawn square rule. Here, Black is outside the square and cannot enter it, but the game is drawn because of stalemate:

```
[FEN "K7/P7/3k4/8/8/8/8/8 b - - 0 1"]

1... Kc7

```

So now, to be complete, we'd have to exclude the situation where the White king is in the corner, blocking his own pawn, and Black can trap him in that corner. This function is getting very convoluted already, and that's just one of the most basic concepts.

# Answer
> 1 votes
Case 1: Both kings are away from the passed pawn: IF Black can get into the square, it is a draw.

Case 2: The Black King is in front of the pawn: depends on the position of the White King

Case 3: Black's king is outside the square, but White has a rook-pawn - If Black's king is in front of the pawn, it is a stalemate, and in some other cases, White's king may be trapped in a corner and stalemated.

---
Tags: endgame, mathematics, pawn-endgame
---


# Question
Title: Why is better for white to move Rxa7 instead of Nxd3?
I am trying to analyze the below middle game with White to move. I played Nxd3 to capture Black's queen. However, the engine analysis says that a better move is Rxa7.

```
[FEN "r5k1/r4pp1/3P3p/8/8/1p1qP1P1/1Np2P1P/R1R3K1 w - - 0 1"]

```

If I stick to my play, I expect the these moves-1. Nxd3 Rxa1 2. Rxa1 Rxa1. White would gain a queen and a rook, while Black will gain two rooks.

If I follow the engines suggestion, I expect the these moves- 1. Rxa7 Qd5 2. Rxa8 Qxa8. White would gain two rooks, while Black will gain one rook.

From the perspective of white, wouldn't it be better to capture the Black queen? Black certainly seems to have a stronger position, but letting the Black queen go seems counterintuitive to me. I am certainly missing something and would appreciate your insights here.

# Answer
Both rooks control White's back rank. If they are removed through:

1. Nxd3 Rxa1
2. Rxa1 Rxa1

Then both pawns cannot be stopped at the same time by the single knight, guaranteeing Black a Queen-Rook endgame. Let's assume White plays Kg2 next:

3. Kg2 c1=Q
4. Nxc1 Rxc1

Then the pawn at b3 will surely become a Queen. A worse move but still wins:

3. Kg2 b2
4. Nxb2 c1=Q

Because Black still has a Queen and the rook versus White's only minor piece, the Knight.

---

We also should notice White's passed pawn at d6. So even with d7:

1. d7 c1=Q+
2. Nxc1 Rxc1+
3. Kg2 Rd1

Rd1 prevents White from promoting:

4. d8=Q+ Rxd8
> 4 votes

# Answer
If ..Nxd3, Rxa1 Rxa1, Rxa1+ now the problem for white is the pawn on c2 is about to promote and if Kg2, c1=Q Nxc1, Rxc1 and now black is up a rook!

If ..Nxd3, Rxa1 and black waits with Kf1 here, it will end up in the same sequence of the c2 promoting and the knight has to be given up.
> 2 votes

# Answer
If White takes the Black queen, Black wins more quickly with ...Rxa1, Rxa1 Rxa1 and another pawn will promote to a queen. If White trades rooks, Black has to wait a few more moves before promoting.
> 0 votes

---
Tags: engines, analysis
---


# Question
Title: What is the best defense against the King's Indian Attack?
How can I break the King's Indian Attack? I think my h7 square is vulnerable to attack; what is the best way to break this strategy?

# Answer
I doubt that the King's Indian Attack can be 'broken'. It's a very solid position that White takes the time to setup, if Black is not careful, White may be able to gain space on the kingside, with moves such as e5, and develop dangerous attacks if Black has castled there.

As for h7 being weak, many things need to happen from Black in order for this to be realized (such as a semi-open h-file, Bg7 has been exchanged, in which case it is h6 that is weaker), so there may not be anything there worth exploring.

I can't comment on what the 'best' defense would be, but there are many good ones, one such is the Botvinnik System. Black makes use of the extra available tempi to set up a strong and flexible defense. The typical structure would be pawns at c5, e5, d6, g6 and pieces at Nc6, Nge7, Bg7 and 0-0. Black has a firm control over the d4 square and can potentially break with either `...b5` or `...f5`.
> 9 votes

# Answer
I recently faced a very similar problem when I organized a King's Indian Attack themed blitz tournament at my club. The problem is that it takes quite a few moves to establish White's KIA position and I had to find moves for black that preserved Black's flexibility in light of the many Youtube videos out there that promise to "crush Black with the KIA" :-).

The solution I came up with was to follow a line recommended by England's "Ginger GM", Simon Williams in his series of videos on the French Defence. It goes like this:

```
[fen ""]
1. e4 e6 2. d3 d5 3. Nd2 c5 4. Ngf3 Nc6 5. g3 g6 6. Bg2 Bg7 7. O-O Nge7 8. Re1 b6

```

There are a number of ideas here.

1. The King's knight has gone to e7 not f6. This is important because it takes the sting out of e5 by White and of ed. The e file is blocked by the knight on e7 and Black's king sheltered.
2. Black has delayed castling. There is no urgency and castling queenside may be more appropriate. In any case don't castle automatically into the programmed KIA king's side attack. Make your opponent think! Try and frustrate his plans.
3. Black is ready to meet ed with ed and O-O. If necessary then a5, Ra7 will redeploy the queenside rook along the 7th rank opening up new defensive and attacking possibilities.
4. Black will meet e5 with moves like Qc7 and g5 with the idea of exchanging his g pawn for White's e pawn and if White defends with Qe2 Black will happily initiate the exchange of queens on e5. Black is more likely to castle queenside in this variation
5. If White follows a traditional move order with moves like c3, Nf1 h5 etc then Black will respond with something like h6, a5, Ra7, Rd7 with threats to play either de to embarrass the White queen or d4 to drive a wedge into the center and take space.

Of course this does not refute the KIA but it does give a flexible and rich way to combat White players who bang out the first 10 or 12 moves like an automaton.
> 2 votes

# Answer
So far, I’ve had success with the Pachman System, d5 g6 Bg7 e5 Ne7. If they play d4 before you can get the e5 off, you can go for Nf6, Nd7, and Nb6, allowing you to capture any c4 pawn, and get a good position while they recapture.
> 1 votes

# Answer
I believe that the best way is to stop your opponent from getting an imbalance by copying White's setup. This will lead to drawish positions, if you are aiming for a draw. If you are aiming for a win, then you should then control the center after these moves.
> 0 votes

---
Tags: opening, strategy, kings-indian
---


title: Bird's opening versus the Dutch Defence

text:
# Question
Title: Bird's opening versus the Dutch Defence
I have played Bird's opening for around a year now, but I don't understand why Bird's opening isn't played as much as the Dutch, even though it is a tempo up. Why is this?

# Answer
Even if you play the Dutch a tempo up, you don't have great chances of gaining an advantage (especially if your opponent is completely satisfied with just equalizing). As White you typically want to maximize your chances of getting some edge, and a better way to do this is by controlling more of the centre with 1.e4/1.d4, or perhaps developing a piece with 1.Nf3. The Bird's still a fine opening, but not very challenging.

In addition to this, Black doesn't necessarily have to play 1...d5 (even though it's the most popular move). He could go for something like 1...c5, 2...Nc6, 3...g6, 4...Bg7, 5...e6, etc, playing similar to how he would against the Closed Sicilian. If at any point White decides to push e4, then we've actually got some kind of Closed Sicilian where Black is fine. And if White doesn't push e4, it's kind of odd - after all, in the Bird/Dutch isn't one of the main goals to push e4/...e5?
> 3 votes

# Answer
From my experience in playing the dutch(leningrad and stonewall) and the bird(typically reverse leningrad dutch), I feel its very tough to get an edge but lets people get a levelled game. You also don't really surprise people. Half my games goes something like this f4 d5 Nf3 c5 g3 g6 Bg2 Bg7 O-O Nf6 d3 O-O, and from here white has several options but even in white manages to get e4 in, there doesn't seem to be a path to advantage. You don't get a surprise factor when you reach this position either, since most d4 players have experience in this type of structure against the dutch systems. Another big portion, against the sicilian players, gets something similar to the closed sicilian. And there are of course other legitimate options. The only things going for it is

1. unfamiliar to opponents(though as mentioned above, sicilian and d4 players typically comfortable). e4 players may have some problems dealing with this however, as they can't borrow their knowledge from else where.
2. from's gambit is bad. Just accept it. Less recommended is to transpose to the king's gambit, but if you know your opponent doesn't have experience in the king's gambit, you could use that to your advantage.
> 2 votes

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Tags: opening, dutch-defense, birds-opening
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title: Countering the Horowitz Defense

text:
# Question
Title: Countering the Horowitz Defense
Since my last post I've successfully learned how to counter the wayward queen attack, and now I've run into an interesting opening that I don't immediately lose to, but I feel I can play against better.

Typically as white I like to play the Queens Gambit. Being still new I stick to what I know. A VERY VERY common opening for black against the queens gambit in the 700-900 range (on chess.com) seems to be the Horowitz Defense.

```
[FEN ""]
[StartPly "6"]

1. d4 e6

```

Generally, I tend to continue with the queens gambit, moving `2. c4`. My justification being an early deployment of his dark bishop would give check but theres plenty of (safe) ways to mitigate it and continue to develop my pieces. However, I feel there's strategy here I don't see. I haven't searched chessbase yet (will do that tomorrow) but I don't usually see this opening in club games.

Is there a better counter to it than `2. c4`, are there specific master games I can study?

thank you!

# Answer
Since you are playing the Queen Gambit, **2.c4** is indeed the most logical way to continue. The main answers, 2...d5 and 2...Nf6, should fit in your repertoire anyway. The alternative is to go for **2.Nf3** first.

**Move order finesses**

Black's move order bears three subtelties:

* You are offered a choice to switch to a French opening with 2.e4. This is probably your opponent's secret hope and since you are a 1.d4 player, you will probably not want to go down that road even though 2.e4 is of course a good move - unless you are fond of playing against the French defense.
* After 2.c4, Black can bring the game to original territory with 2...Bb4+. This is a decent line, but not overly dangerous, and you can handle it with general rules (develop, avoid doubled pawns, castle...) if reaching an equal position suits you. Or you can learn a bit of theory about it, although at 700-900 level there are a lot of more important stuff for you to study. If you want to avoid it altogether, you can start with 2.Nf3. Then 2...d5 3.c4 is back to QGD, with an early Nf3, which might or might not suit you depending on your favorite line of Queen Gambit. Note that 3...Bb4+ remains a decent option for Black.
* Dutch players often start with 1...e6 to provoque 2.c4 and reduce their opponent choice: after 1.d4 f5 White often goes 2.g3 or 2.Nf3 and plays c4 only a few moves later, or even plays subvariations like 2.Bg5 or 2.e4, but after 1.d4 e6 2.c4 f5 those options are lost. If you play an early 2.c4 against the Dutch anyway, you won't mind those shenanigans at all, otherwise 2.Nf3 might once again be the solution.

Finally, some Black players also intend 2...b6 or other rare moves you should not be too worried about.

**Conclusion**

1...e6 is a decent move that plans to reach normal positions while limiting your choice. Those move-order subtelties are interesting when building your repertoire, yet they should not worry you too much until you reach a level around 1800 or so.

The natural alternative for a Queen's Gambit player is between **2.c4** and **2.Nf3**; both have pluses and minuses. If it fits your usual way of playing in the QGD, go for 2.Nf3 first before 3.c4 and go for standard, QGD-like development: that avoids 2...Bb4+ tricks and requires less specific work on opening lines that shouldn't be your biggest concern right now.
> 11 votes

# Answer
If you are happy playing the white side of a French Defence then I would play e4. If black is playing e6 because he wants to avoid some white QGD lines then this could make him unhappy.
> 2 votes

# Answer
Black may be able to play the Bogo-indian, The QID, the Nimzo-indian, and such openings. I suggest that you learn the theory of the French and play that.
> 0 votes

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Tags: opening, queens-gambit
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