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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 piecepieces 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.

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 piece 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 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?

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.

1
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Can you castle with a "ghost" rook?

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 piece 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 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?