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Originally posted by BigDoggProblemThe board has to be upside down i.e. the black king is on the h7 not the a2 because there is no legal way for the black king to arrive on this square. Given that the board is the other way around, white to move:
This is a problem I posted in the Chess Forum, but it got buried in a long thread.
[fen]8/2p5/8/2B5/8/8/kPP5/1RK5[/fen]
Mate in 2
Rh8 check, KxR (forced), g pawn queens and mates
Edit: oops just noticed it was already answered sorry
Originally posted by stevetoddthat's what i thought steve, but the rook's protected.. now, for god's sake man run. RUN! before bigdog pounces on you
[b]The board has to be upside down i.e. the black king is on the h7 not the a2 because there is no legal way for the black king to arrive on this square. Given that the board is the other way around, white to move:
Rh8 check, KxR (forced), g pawn queens and mates
Originally posted by pootstickthe black king could have reached the position via the first rank. Just an example:
that's what i thought steve, but the rook's protected.. now, for god's sake man run. RUN! before bigdog pounces on you
1. ... Kd1 2.Kc3 Kc1 3.Kd3 Kb1 4.Ke2 Ka2 5.Kd2 Rb1 6.Rxb1 Rc1 7.Kxc1
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Originally posted by Mephisto2lol well it's legal I concede but not very likely is it. This problem does have me stumped
the black king could have reached the position via the first rank. Just an example:
[fen]8/2p5/8/2B5/8/1K6/1PP1k3/5rRr b - - 0 1[/fen]
1. ... Kd1 2.Kc3 Kc1 3.Kd3 Kb1 4.Ke2 Ka2 5.Kd2 Rb1 6.Rxb1 Rc1 7.Kxc1
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Originally posted by pootstickThe board does not have to be upside down, it's as someone psoted (I really must start reading the entire thread before leaping in) black to move:
that's what i thought steve, but the rook's protected.. now, for god's sake man run. RUN! before bigdog pounces on you
has to move c6, b4, black has to move a3, Ra1 is mate. I do not believe that another legal solution exists therefore for the problem to be correctly asked it has to be blacks move, otherwise I do not believe there is a mate in 2.
Originally posted by stevetoddThe real reason it is Black's move is because Black could not have moved last. A composer would not expect the solver to simply guess which conventions (like "White to move" in forced mates) to change; he will provide a way of proving that it is Black's move.
The board does not have to be upside down, it's as someone psoted (I really must start reading the entire thread before leaping in) black to move:
has to move c6, b4, black has to move a3, Ra1 is mate. I do not believe that another legal solution exists therefore for the problem to be correctly asked it has to be blacks move, otherwise I do not believe there is a mate in 2.
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Originally posted by BigDoggProblemas there is no other way to solve the problem! i.e the only legal solution that exists, that is enough to justify the answer, therefore it's not guesswork. It wasn't guesswork as I worked through ALL of the possible scenrarios and this is the only one that works, so it is not guesswork! Sometimes the only way to prove something (not necessarily saying this was the only way to prove it, but its a fact and you know it) is by eliminating the impossible and leaving the only possible answer!
The real reason it is Black's move is because Black could not have moved last. A composer would not expect the solver to simply guess which conventions (like "White to move" in forced mates) to change; he will provide a way of proving that it is Black's move.
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Originally posted by stevetoddas there is no other way to solve the problem!
as there is no other way to solve the problem! i.e the only legal solution that exists, that is enough to justify the answer, therefore it's not guesswork. It wasn't guesswork as I worked through ALL of the possible scenrarios and this is the only one that works, so it is not guesswork! Sometimes the only way to prove something (not necessarily saying this ...[text shortened]... a fact and you know it) is by eliminating the impossible and leaving the only possible answer!
The reason this sort of justification is not accepted in modern chess problems is so the solver is not obliged to labor futilely in the event that the composer makes a mistake. If there is no solution according to accepted conventions, and no proof that said convention(s) no longer hold, the solver can correctly claim that the problem is unsound.
i.e the only legal solution that exists, that is enough to justify the answer
I agree with this statement, because the word 'legal' implies a look at the history of the position as well as the forward moves.
It wasn't guesswork as I worked through ALL of the possible scenrarios and this is the only one that works, so it is not guesswork!
But there are always more possible scenarios. Maybe the composer set up the board with a dark square in the righthand corner, and the board should be rotated 90 degrees. Or maybe there is a deliberately illegal thing that, once corrected, yields solutions. I've seen "joke" problems that had 9 pawns of one color, with a different mate in 2 regardless of which '9th pawn' was removed. Do we as solvers really want to subject ourselves to this kind of 'joke' problem with no advance warning?
Sometimes the only way to prove something (not necessarily saying this was the only way to prove it, but its a fact and you know it) is by eliminating the impossible and leaving the only possible answer!
Again, there are acceptable ways of doing this (retro analysis to determine whose move it must be) and unacceptable (changing conventions and rules arbitrarily until the problem yields a solution). I've tried to explain above why the latter method is considered unacceptable (by most serious problemists, not just me) - mainly for solvers' protection, and to keep composers honest.
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Originally posted by BigDoggProblemThere is only one possible answer therefore it is the answer, if not tell me I am wrong and give an alternative solution, I really do not know why you are taking such an aggressive stance, chess is supposed to be fun, chill out (somewhere along the line I think you have got the impression that I have insulted you and I have not)
[b]as there is no other way to solve the problem!
The reason this sort of justification is not accepted in modern chess problems is so the solver is not obliged to labor futilely in the event that the composer makes a mistake. If there is no solution according to accepted conventions, and no proof that said convention(s) no longer hold, the sol emists, not just me) - mainly for solvers' protection, and to keep composers honest.[/b]
Originally posted by stevetoddHuh? My replies to you have only been technical discussion of chess problems and the accepted conventions used in the problemist world.
There is only one possible answer therefore it is the answer, if not tell me I am wrong and give an alternative solution, I really do not know why you are taking such an aggressive stance, chess is supposed to be fun, chill out (somewhere along the line I think you have got the impression that I have insulted you and I have not)
Unfortunately, some chess problems don't have a solution. Chess composition can be a tricky business, and composers are human. Their intended solution may not be sound, and they may not have an alternate one to give you.
If you wish to prod around with the rules until a solution emerges, be my guest, but don't say you weren't warned!
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Originally posted by BigDoggProblem
Huh? My replies to you have only been technical discussion of chess problems and the accepted conventions used in the problemist world.
Unfortunately, some chess problems don't have a solution. Chess composition can be a tricky business, and composers are human. Their intended solution may not be sound, and they may not have an alternate one to gi ...[text shortened]... round with the rules until a solution emerges, be my guest, but don't say you weren't warned!
Originally posted by BigDoggProblemVhy of course I vill darling, vhy vould I keep secrets from you?
Huh? My replies to you have only been technical discussion of chess problems and the accepted conventions used in the problemist world.
Unfortunately, some chess problems don't have a solution. Chess composition can be a tricky business, and composers are human. Their intended solution may not be sound, and they may not have an alternate one to gi ...[text shortened]... round with the rules until a solution emerges, be my guest, but don't say you weren't warned!