Illegal Position Contest!

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Arisktotle
Leither123 wrote:

Forgot about white's dark squared bishop:

I was a bit confused on this version but it's still legal in the same way as the last one. However white needs to unpromote a piece on b8 to allow the black uncaptures.

EvinSung

please show a game if its legal position

Leither123

I've messed up pretty badly on my previous position, but I know that this one is definitely illegal:

TheAuthorOfChickens

I feel like this is an extremely illegal position.

n9531l1
TheAuthorOfChickens wrote:

I feel like this is an extremely illegal position.

My feeling is that it is slightly illegal rather than extremely illegal, since the proof of illegality is extremely simple.

Bonus question: Could this position arise in a game of bughouse?

Kyobir
bald55
Arisktotle
Leither123 wrote in #7641:

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.

Arisktotle
Leither123 wrote in #7642:

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.

Arisktotle
bald55 wrote in #7647:

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.

n9531l1
Arisktotle wrote:
bald55 wrote in #7647:

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?

Leither123

You know, I forgot that black even had a queen.

There should finally be no more discoveries:

KieferSmith
Leither123 wrote:

You know, I forgot that black even had a queen.

There should finally be no more discoveries:

last move was g2-g3+

EndgameEnthusiast2357
KieferSmith wrote:
Leither123 wrote:

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?

Arisktotle
Leither123 wrote:

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 wink

Arisktotle
n9531l1 wrote:

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!

Arisktotle
Arisktotle wrote:
Leither123 wrote:

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!

linorder
update: i forgot white's king :facepalm
n9531l1
linorder wrote:
 
update: i forgot white's king :facepalm

Legal position.

n9531l1
Arisktotle wrote:
bald55 wrote in #7647:

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.