I think the first move is 1.Rxb6
Rxb6 gxh6 (...Rxh6 b7 and no matter what Black plays, White will play b8=Q (or b8=R). If neither ...Rxh6 or ...gxh6 is played, there is just 2.Rxh8#.) 2.g7 and then Black moves the rook. (If black moves king, then there is gxh8=Q# (or qxh8=R#.). After this, there is b7 then b8=Q# or b8=R#.
I think the first move is 1.Rxb6
Rxb6 gxh6 (...Rxh6 b7 and no matter what Black plays, White will play b8=Q (or b8=R). If neither ...Rxh6 or ...gxh6 is played, there is just 2.Rxh8#.) 2.g7 and then Black moves the rook. (If black moves king, then there is gxh8=Q# (or qxh8=R#.). After this, there is b7 then b8=Q# or b8=R#.
Just correcting this because I cannot edit: the qxh8=R# part of the text was supposed to be gxh8=R#.
1. A composed problem position is not a snapshot of an actual game and does not have a past, it has a collection of possible pasts. Moves made from the starting position can change that collection.
2. If you use the site's diagram editor to post a problem position, the information provided about castling has to be ignored, since that information must be inferred from the possible pasts of the position.
1. I know and understand, but I don't feel obliged.
2. If you post a diagram in an online format with FEN extractable, all possible clever specifics (side of the board, side to move, en passants, castlings) are determined and given away. Speculations are inappropriate. If you want to hide them, use image format.
Speculations are inappropriate. If you want to hide them, use image format.
That would have been difficult for me, since I didn't post the position. But I did know enough about problem conventions to disregard the FEN.
Problem solving would stop being enjoyable for me if each composer got to make up his or her own conventions. There is a widely accepted convention about how castling rights are determined in a composition.
as RubenHogenhout showed in comment 170, a legal game where black has castling right.
so there must be another line of solution.
No one is disputing that both players can castle in the problem's starting position, since there is at least one history in which White can castle, and at least one history in which Black can castle. But there is no history in which both sides still have castling rights.
There is still only one way to mate in 4. It is after White castles, on the second move of that mate in 4, that the position no longer has a history in which Black could have castling rights, and thus Black cannot castle.
i agree with you that in one line its M4.
but i think, the whole problem or composition isn't M4 if its not M4 in all lines.
i mean we dont have mate in 4 if the game arrived through as comment 170.
You know, if you look at further comments then you see, all lines =M4
it is so easy
You know, if you look at further comments then you see, all lines =M4
no. in one type of history lines, white doesn't has castling right, but black has.
in this case there is no M4.
You know, if you look at further comments then you see, all lines =M4
no. in one type of history lines, white doesn't has castling right, but black has.
in this case there is no M4.
A position is given with the stipulation, White to play and mate in 4.
Solver A discovers a mate in 5 and presents a proof game to show that it is a valid mate in 5. Solver B discovers a mate in 4 and presents an analysis to show that it is a valid mate in 4.
Which solver gets credit for finding the solution?
You know, if you look at further comments then you see, all lines =M4
no. in one type of history lines, white doesn't has castling right, but black has.
in this case there is no M4.
A position is given with the stipulation, White to play and mate in 4.
Solver A discovers a mate in 5 and presents a proof game to show that it is a valid mate in 5. Solver B discovers a mate in 4 and presents an analysis to show that it is a valid mate in 4.
Which solver gets credit for finding the solution?
what if, the 'wrong' is in composers part? he didn't analysed all type of history lines.
its not a complete solution if you exclude one type of history line.
I think the first move is 1.Rxb6