I've messed up pretty badly on my previous position, but I know that this one is definitely illegal:
Yes it is. It does not depend on the retractions in the center. The general configuration is illegal since there is no promotion square for black's light-squared bishop - without an extra capture on the same file. Considering that [Rh1] is a lost boy white would need 17 pieces in the game setup.
Obvious nonsense but gave me an idea for a new challenge type:
Create an illegal position where the question is: What is the least number of units to remove or add to make this position legal? Specify which where possible.
You can take this one as an example - though it is painfully simple of course.
Obvious nonsense but gave me an idea for a new challenge type:
Create an illegal position where the question is: What is the least number of units to remove or add to make this position legal? Specify which where possible.
You can take this one as an example - though it is painfully simple of course.
I like this idea of a way to deal with the obvious nonsense positions we sometimes get.
I can reach the #7647 position after removing six units from the board. Can someone do it with fewer?
You know, I forgot that black even had a queen.
There should finally be no more discoveries:
You know, I forgot that black even had a queen.
There should finally be no more discoveries:
last move was g2-g3+
You know, I forgot that black even had a queen.
There should finally be no more discoveries:
last move was g2-g3+
And how did the bishop ever get on h1 then?
You know, I forgot that black even had a queen.
There should finally be no more discoveries:
Looks OK now. Though you'd probably have preferred to keep f3xQg4 as a "try". The composer's life is full of compromises 
I like this idea of a way to deal with the obvious nonsense positions we sometimes get.I can reach the #7647 position after removing six units from the board. Can someone do it with fewer?
That was the idea! But there are probably also positions where a clever addition or removal of units gets a rewarding result!
You know, I forgot that black even had a queen.
There should finally be no more discoveries:
Looks OK now. Though you'd probably have preferred to keep f3xQg4 as a "try". The composer's life is full of compromises
Actually there is a plus to your latest diagram which prolongs the retractions with 2 single moves before it crashes. Look at these reverse last moves: .Rf3-c3+ Re4xPc4+ .Pd3xQc4+ Qd4-c4+ Qb2-b3+ ?? Phew, something useful done with the black queen!
Legal position.
You can take this one as an example - though it is painfully simple of course.
The game I made with six units removed didn't seem painfully simple to me. I'm wondering if I missed something simpler.
The game I made with six units removed didn't seem painfully simple to me. I'm wondering if I missed something simpler.
Ah, I didn't look at any proof game - only at the removal of units to make it apparently legal. When I look closer it is indeed not as simple as I thought in the first place. Good achievement to do it by just removing 6 units! I see how it works!
The original position had a pawn on the c-file to prevent a promotion, but after switching the rook for a pawn and then for a bishop, I forgot to add the pawn back. I've checked over this position and I believe it is finally problem-free:
It appears now that the last move f3xQg4 works again.