pawn h6
requires captures to get there
not available
Illegal Position Contest!
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this is a legal position
HockeyFox7 wrote:
n9531l1 wrote:
I hope this position will be a little more challenging. It was submitted as a helpmate in 10 problem (Evgen S. Orlov, 5516 The Ural's Problemist 60 2009). Why is it illegal?
It is illegal because Black's g-pawn couldn't get over the the right!!!!
Also illegal because the coordinates are wrong, because h1 is a dark square, and a1 is a light square! (I just looked at a normal board)
watch:
ThebestA9player wrote:
white to move
thats legal
Ilampozhil25 wrote:
and making it illegal
um do you mean the pawn on h5 or h4?
and this is legal as white to move. nobody ever said black had to be able to castle.
natureexplorer wrote:
Okay, I have an idea. I know by counting the White pieces that Black captured 7 times (that includes the captures that happen in the process of trading). Let's see if the pawns can capture enough times to reach the positions they are at in the position shown. I'm counting...
Now you are on the right track.
Sameer_chess-player wrote:
this is a legal position
Yes, easily legal. But we want to see illegal positions that look like they could be legal.
Sameer_chess-player wrote:
watch:
If you'd like to see it done in 20 moves instead of 29, here it is.
Sameer_chess-player wrote:
ThebestA9player wrote:
white to move
thats legal
The other solution, in the next post after the problem was posted, used the bishop instead of the queen to lose a move. Both work equally well.
Sameer_chess-player wrote:
and this is legal as white to move. nobody ever said black had to be able to castle.
I'm not sure what the point of this one is. Your final position is the same as the position you had after move 1.
May 12, 2021
0
#4758
#4729 or # 4788, from n9531l1 : It is illegal because: 1. Remaining white pawns have performed at least three captures to reach their current positions. [e.g. fxg, bxc, exd] This is legal for their are three black pieces missing 2. The seven black pawns from c-file up to h-file must have done at least seven captures of white pieces. This is legal as well, for their are seven white pieces missing [ e.g. gxh, fxg exf, dxexf, bxc, cxd ] So, all captured white pieces must have been taken by black pawns! 3. But one of these seven white pieces is a white pawn, and in case of the white a-pawn, then it was captured by a black b-pawn. But the black b-pawn captured to the c-file [see 2.], so the black a-pawn needed to capture an white piece number eight to reach the b-file first. But there are still nine white pieces... If it wasn't the white a-pawn which has been captured among the seven black captures, the white a-pawn has moved to the c-file by two captures, which totals then to at least four black pieces captured by white. But there are still thirteen black pieces .... So the position is illegal. But probably there is shorter argumentation?
That's correct. I think natureexplorer was also about to find it. It can be explained a little more briefly. White's three available captures were pawn captures to make three pairs of doubled pawns. Black's seven available captures were all made by six pawns, one each by bcefg pawns and two by the d-pawn, with all six ending on the c through h files. So neither side's a-pawn was captured or could have promoted, but White's a-pawn has disappeared (illegally) from the board.
Mikey383 wrote:
I think this position [#4764] is illegal if it's white to move.
No one has tried to answer my questions at #4773 about this legal position, so I'll ask them again. Is the position still legal if a black queen is placed at f6? Does who has to end up with the move make a difference in the legality?
I'll wait a while for a response, and then give my answers, to see if anyone disputes them.
I hope this position will be a little more challenging. It was submitted as a helpmate in 10 problem (Evgen S. Orlov, 5516 The Ural's Problemist 60 2009). Why is it illegal?
It is illegal because Black's g-pawn couldn't get over the the right!!!!