16 May 07
Originally posted by SwissGambitAlright. I think I've got the solution. All or nothing, here's my final answer. I'm positive the position with the f1 B is illegal. As far as I can tell the only way that the bishop could have administered the check is by the king moving out of the way. The king could have been on f3, with the previous position (diagram)
[fen]8/8/2kP4/5r1b/8/6Kp/7P/2R2bBB b - - 0 1[/fen]
Is the position legal?
a) diagram
b) wQh1 instead of wB
Edit: Prove your answer.
black just played Bh5+... with the continuation of 1. g4 f4xg4+ en passant 2. kxg3+ d5 2. c5xd5+ en passant. The only issue is that the B could never have made it to h1 without the g2 pawn moving, thus making the f4xg4 en passant and black's double check and the position illegal.
16 May 07
Originally posted by JirakonCorrect. The answer for a) is "no" and b) is "yes".
The only issue is that the B could never have made it to h1 without the g2 pawn moving, thus making the f4xg4 en passant and black's double check and the position illegal.
That's why putting a queen there instead makes the position legal.