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I recently saw this mate-in-2 problem

[title "White to mate in 2"]
[fen "8/8/8/2B5/2p5/1kp5/8/R3K3 w - - 0 1"]

This was posed with the hint that the player of the White pieces was a strong player and Black was a novice. The take away was that White was offering rook odds, started the game without a rook on a1 and the rook now on a1 had started on h1.

The key was that White castles queenside with the ghost of the rook given as odds so the king moved from e1 to c1 and the rook on a1 stayed where it was. This forces Black to play c2 allowing White to play Ra3 mate.

This raises two questions:

  1. Is castling with a "ghost" rook like this legal where there has never been a rook on a1 because it was given as odds at the start of the game?
  2. Is castling with a "ghost" rook like this legal where there was a rook on a1 at the start of the game but it was captured before it could move?

The replayer doesn't like it. It will only allow castling with a real rook.

  • 4
    I may be completely make things up here, but to my knowledge you can't castle to a ghost rook no matter the situation. So if you started without your A1 rook you can't castle queenside no matter what. – Isac Aug 11 at 13:54
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    The FIDE laws of chess don't recognise piece odds at all, so any rules involved in this "puzzle" would have to be made up anyway – konsolas Aug 11 at 14:25
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    @konsolas All rules are made up. The FIDE laws of chess are made up by FIDE. Odds games were commonplace in the 19th century and I'm sure there were rules in place, just not made by FIDE which didn't come into existence until 1924. Howard Staunton was a leading player (some would say first world champion) during this time and may have defined some rules. – Brian Towers Aug 11 at 17:04
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    You are asking whether a move is legal, but then in the next breath you say that you don't care which set of rules you are using. These two stances contradict each other. (By the way, I think this problem is ridiculous. Of course you can't castle with a ghost rook! Just don't ask me to give you a reference, because this situation has probably never been rigorously codified.) – TonyK Aug 11 at 19:41
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    If castling with a ghost rook were legal, would it then also be legal for white to spend a turn moving the ghost rook instead of one of his "real" pieces (effectively making no move in that turn)? – marcelm Aug 11 at 22:10
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The second part of the question is more straightforward, so I'll look at that first.

Is castling with a "ghost" rook like this legal where there was a rook on a1 at the start of the game but it was captured before it could move?

Article 3.8.2 of the FIDE Laws of Chess describes how castling works:

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.

This explicitly states that castling involves two pieces, the king and the rook, and it describes how the rook moves in this manoeuvre. If you don't have an unmoved rook on the board then you can't castle. Therefore castling with a "ghost" rook is illegal.

With this clear the first part becomes easier to answer.

Is castling with a "ghost" rook like this legal where there has never been a rook on a1 because it was given as odds at the start of the game?

It depends on the rules of the competition or individual game, if the game is a one-off. If the rules state that apart from the initial position of the board the FIDE Laws of Chess apply then clearly it is illegal.

In the absence of such a clarification the best guide is probably the chess historian Edward Winter. In his chess notes for March 2009, note 6029 he considers exactly this question:

6029. Castling with a phantom rook From Mark Thornton (Cambridge, England):

‘In rook-odds games could the odds-giver castle with the “phantom rook”? For example, if White gave the odds of his queen’s rook, could he play Ke1-c1? And, if so, were the castling rules the same as if the rook were present?’

According to Winter there is no conclusive ruling one way or the other. He quotes probably the most sensible approach from Howard Staunton on page 35 of Chess Praxis (London, 1860):

When a player gives the odds of his king’s or queen’s rook, he must not castle (or, more properly speaking, leap his king) on the side from whence he takes off the rook, unless before commencing the game or match he stipulates to have the privilege of so doing.

There are strong feelings on both sides of the argument. Here is more from Winter:

However, in a review of the book on pages 88-89 of the March 1890 BCM Edward Freeborough disagreed. After stating, with respect to level games, that castling should be described as a move of the king and that the king should therefore be moved first, Freeborough observed:

It follows logically that the fact of giving the odds of a rook ought not to deprive the king of his privilege of taking two steps to the right or left as his first move.

Page 36 of The British Chess Code (London, 1903) stated:

In the absence of agreement to a different effect, a player may castle (by moving his king as in ordinary castling) on a side from which, before the commencement of the game, the player’s rook has been removed, provided that this rook’s square is unoccupied and has been unoccupied throughout the game, and that the same conditions as to squares and as to the king are fulfilled which are required for ordinary castling on this side.’

The above text was quoted on page 275 of the June 1916 Chess Amateur when a revised edition of the Code was envisaged. Comments were invited, and on page 305 of the July 1916 issue ‘Simplex’ wrote:

This I think sheer nonsense. If a player gave me a rook and wanted to castle on this rook’s side, I should say, “No, you don’t, you can’t castle without a castle”. Let’s have no pretence. If a player gives a rook, let him give it totally not half. Receivers of odds are not strong players, and to see the nominal giver of odds move his king a couple of squares would be disconcerting. No; if a player gives odds let him give them without pretence.

A contrary view was expressed by W.S. Branch on pages 333-334 of the August 1916 Chess Amateur:

Re Chess Laws, page 305 (July), and as to “castling without rook”, I would say, first, that you can’t “castle the king” – the full and proper term, of which “castles” is an abridgment – without a castle. The phrase should be “moving the king as in castling”. I believe that the right of the odds-giver to move his king, once in a game, as in castling, has always been upheld since “castling” was invented (sixteenth century). It existed, as part of the “king’s leap”, long before “castling” was invented, and long before the rook was ever called a “castle”. The giving of the rook as odds should not deprive the king of any of his rights.’

Branch then gave further historical details regarding the king’s leap. By 1916, however, the practice of giving odds was disappearing, without any formal resolution of the ‘phantom rook’ question.

Winter revisits this topic in note 6035. "Castling with a phantom rook (C.N. 6029)" with some interesting anecdotes regarding castling with a ghost or phantom rook.

  • 3
    Great answer. Interesting points of view. Clearly there is no formal set of rules that provides the 'correct' ruling; it must be agreed beforehand, or else the odds-giver should not try to connive for something that may seem arbitrary to a novice. – Grade 'Eh' Bacon Aug 16 at 17:10
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    I enjoyed that historical overview. – TRiG Sep 4 at 9:10
  • The quotation from the 1903 British Chess Code, though allowing castling with a ghost rook, would not allow the proposed solution to the puzzle in the question, because it says "provided that this rook's square is unoccupied ...". In the puzzle, the gist rook's square is occupied by another rook. – Andreas Blass Sep 7 at 1:54
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No, not really. Some problemists might use your case 1 as a joke, but it's not really legal. Your case 2 is certainly not legal (even if the rook had never moved).

  • 4
    As a joke, I'm imagining a directmate where the key is to capture a ghost rook to prevent ghost castling as a defence. If nobody's done it yet there's still time until April next year. – Remellion Aug 11 at 15:37
  • Hey @Remellion, I took you idea and turned it into an actual problem! ;-) And it's been less than an hour since your proposal! – Rewan Demontay Aug 11 at 16:38
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    Wiki says you can castle with the "ghost rook", but cites it to some book. I couldn't find any odds games on chessgames where that actually happened, so it's unclear whether it's ever done in practice. – eyeballfrog Aug 12 at 1:33
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    @Remellion What if they weren't given full rook odds, just exchange odds, and the key is to capture the ghost rook with their ghost bishop? – Acccumulation Sep 3 at 22:49
3

@Remellion suggested in a comment, less than an hour ago, for a directmate joke problem in which the key is to capture a ghost rook in order to prevent ghost castling as a defence.

As such, I decided to try to make such a problem just for fun. This is what I came up with.

[Title "Black To Play And Mate In Four Moves, White Odds Of No Ra1"]
[FEN "r6B/1p2p3/8/8/8/3p1k1p/3P4/4K3 b - - 0 1"]

1. Ra1+! Bxa1 2. h2 Bd4 3. h1=Q+ Bg1 4. Qxg1#

EDIT: Many thanks to @Remellion for pointing out a flaw in my original diagram!

EDIT: I believe I have fixed the Rb8 cook. Many thanks go to @Evargalo for showing that Rc8 is not a cook, as follows from their comment: 1...Rc8 2.Bc3 h2 3.0-0-0 Rb8 4.Bb4! And there is no mate to follow in one move.

If Black attempts to push their pawn first, White can simply ghost castle and prevent checkmate in the specified length, although they are still losing either which way. Thus, Black must capture the ghost rook, and ONLY then may they push their pawn.

Now, White can't ghost castle to escape. They try to delay their life but it is futile. They are soon checkmated by a promoted Black queen or rook.

Voila!

I do like how this idea can achieved with such economy of a mere total of just 9 pieces, and how it can be extended to a four-mover.

Also, I suppose the way these "ghost" rooks work is that they ARE OTB technically, but they are invisible, can be moved through, and they can't interact, i.e. moving or attacking, with everyone else, all like a real ghost. But other pieces can chose to not interact with it by sitting on the square, or a one-time capture of the ghost rook is announced.

The technicality here is that since the rook is still there, and that castling counts as like king move, the ghost rook can be moved without ever technically moving on it's own. As such, interesting problems, such as mine, can arise.

An interesting concept that arises from this definition of a ghost rook is that a piece can capture two enemy pieces on the same square. If White's a8 rook moves to a1, a Black piece can actually do a "double-capture" on a1, and take both rooks at the same time.

While these rulesets can be applied to any "ghosted" piece, minus the king of course, the rook is the only interesting case due the castling possiblties that there are to explore.

  • 2
    I like it! Very clever and although you don't directly answer the question you do hint at one of the possible answers I have seen dating from the 19th century. Namely that castling with a "ghost" rook (arising from giving odds) can only take place if the rook's square has not been occupied - i.e. only if the ghost rook hasn't been "captured". – Brian Towers Aug 11 at 17:10
  • Thanks! My answer wasn't meant to directly answer the question, but more to give people an idea of how it works in theory (or at least by my logic anyhow!). Is that acceptable to you? – Rewan Demontay Aug 11 at 17:13
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    Unfortunately this is cooked, but should be salvageable. 1...Re8+ also mates in 4. Add a pair of pawns on the e6/e7 for a crude fix, but there should be something nicer by moving pieces. (Also in directmates, convention is white is the side to give checkmate.) – Remellion Aug 12 at 3:57
  • I have now fixed, but with a single pawn! Thanks for pointing that out! – Rewan Demontay Aug 12 at 4:02
  • Hm still cooked with 1...Rc8, or even 1...Rb8 2. 0-0-0 h2. – Remellion Aug 12 at 7:25
1

There are no official rules regarding games with "odds", so I guess it's up to your taste for this particular case. Anyway, my first thought would be to say "No. You can't" and allowing that possibility would be making a strange twist of the rules that should be specified beforehand

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