I don't see how it's illegal.
Legal or Illegal (yes I know it's old!)
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Extremely simple, but shows the basics. Is this position legal?
The last move of white must have been from Kc2 to c3 giving check. He has to move away from the line of the bishop on a4. That implies that there had to stand something in between that was not giving check when the king was on c2, can move to c3 and then captured by the king. A rook.
The situation is perfectly legal.
Is this legal?
LoekBergman wrote:
The last move of white must have been from Kc2 to c3 giving check. He has to move away from the line of the bishop on a4. That implies that there had to stand something in between that was not giving check when the king was on c2, can move to c3 and then captured by the king. A rook.
The situation is perfectly legal.
Correct.
Ok the last one I posted is silly easy.
Here's a slightly more interesting one. Legal?
I don;t think so. I can see how the bishop got there (before b pawn was pushed) , but not the rook. I may be wrong, but that is my guess.
yes, definetly
True. How about this:
Somehow I liked Sherlock Holmes a lot more than Arabian Knights.
I think so . . . the trick is just the proper timing of g3 and h4.
The rook can enter that cosy corner:
1. h2-h4 Rg3 - Rh3 2. g2-g3 Rh3-h2 etc..
I had made the unfortunate assumption that the bishop had to move somewhere to get to a4, and having it on b3 would contradict the rules as it would imply white's king was in check on black's move.
But yes, if a rook is on b3, then black would indeed be able to deliver a check that wasn't there previously, and Kxc3 would remove it. I guess sometimes you just rule out situations that nobody would ever want to do -- ...Rc3+ could be done, but because no one would want to do it you forget about it. If you can count on your opponent playing terrible chess, the possibilities are nearly endless!
Elubas wrote:
I had made the unfortunate assumption that the bishop had to move somewhere to get to a4, and having it on b3 would contradict the rules as it would imply white's king was in check on black's move.
But yes, if a rook is on b3, then black would indeed be able to deliver a check that wasn't there previously, and Kxc3 would remove it. I guess sometimes you just rule out situations that nobody would ever want to do -- ...Rc3+ could be done, but because no one would want to do it you forget about it. If you can count on your opponent playing terrible chess, the possibilities are nearly endless!
Indeed, most retrograde puzzles count on very strange moves that lead to interesting positions :)
hoynck wrote:
@shoopi
The last one looks extremely difficult to me. But I charish problems like this. Nice one for tomorrow after a good night sleep or the comming weekend.
Thanks.
And I wonder - and shall look for it - wether there is a retrogade group or something like that on Chess.com
I don't know of such group, but be sure to check out the original legal and illegal thread, which has some amazing content in it's 26 pages http://www.chess.com/forum/view/general/legal-and-illegal-positions
There was also another thread called possible or impossible http://www.chess.com/forum/view/fun-with-chess/possible-or-impossible
And something a bit different, a shortest proof game challenge http://www.chess.com/forum/view/more-puzzles/shortest-proof-game-challenge
If you want you can also check out my content. I have recently created 9 original retro puzzles.
#52: illegal. I can't get the king on h1 when he has to change places with the rook and bishop of black. Both can not be the result of promotion, because white has still all his pawns and pieces.
I think both options should be considered possible choices -- that way you don't assume one way or the other. Besides, I like the idea of proving that a position is BS if it is.
Post #7, for example.
Extremely simple, but shows the basics. Is this position legal?