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Illegal Position Contest!
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Leither123 wrote:
Repost (#7849)
I would say it's illegal. The two captures by the black ab pawns use up all Black's available captures. The first capture by White on the king side has to be Pg2xRf3 before the h2 pawn moves, so the black king can later get to the first rank on the way to c2. Then the f1 bishop or h1 rook could get out to be captured on the queen side to let the a8 rook out. But it had to already be out to be captured on f3. So the capture by White on the king side and the capture by Black on the queen side each has to occur before the other, which can't happen in a legal game.
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Correct! Reduced to the bare minimum you will land in the next diagram which is still illegal!
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Leither123 wrote:
Repost (#7848)
What if White is allowed to make an illegal move?
After the illegal move 1. Pg2-f3, the position can be reached easily with legal moves.
n9531l1 wrote:
Leither123 wrote:
Repost (#7848)
What if White is allowed to make an illegal move?
After the illegal move 1. Pg2-f3, the position can be reached easily with legal moves.
Actually that's a good way to define a proper "illegal position" challenge. Every candidate must have a legal proof game with just 1 illegal move. The next challenge could ask for the SPIPG (Shortest Proper Illegal Proof Game) 
Which leaves the question "What exactly counts as a proper illegal move?"
Arisktotle wrote:
Which leaves the question "What exactly counts as a proper illegal move?" In this context?
I suspect that could lead to lengthy arguments.
YES! It requires a list with approved formats.
I made some problems in MDR (Minimun Deviations of the Rules) which permitted small deviations and completing incomplete moves. But it came with quite a lengthy document and I found a number of inconsistencies. I think they cancelled it in the end!
dengeth wrote:
Illegal because rooks can’t jump.
Are you sure? Ever seen castling?
EvinSung wrote:
#7864
Black's rooks and c8 bishop were all captured on the 8th rank, so the g8 knight is the only piece the g2 pawn could have captured, but it needed two captures to reach g4.
If White were allowed to start with the same illegal move as at #7853 (Pg2-f3), the position could be reached with legal moves.
I'm going to take a wild guess that this position is illegal:
I doubt enough pieces could be captured to let pawns promote on the correct color squares for 9 bishops of each side to be opposite colored. So this is my position, perfect for the Christmas Season as well.
fjdkslagh wrote:
n9531l1 wrote:
Arisktotle wrote:
Which leaves the question "What exactly counts as a proper illegal move?" In this context?
I suspect that could lead to lengthy arguments.
if the piece isn't supposed to move like that or it leaves the king in check, it's illegal. Also, if castling is involved, all of the castling rules must be followed.
What you're saying isn't clear. Are you claiming that, in the context being discussed, every illegal move is a proper illegal move, or that no illegal move is a proper illegal move?
The Joke is that black moves first. Which doesn't happen. (:
That's why I said the opening was illegal. You asked for advice.