Illegal Position Contest!

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EvinSung

try to find it for 5857

n9531l1
EvinSung wrote:

try to find it for 5857

DefenderPug2, that's meant for you.  It's #5856 now, and it was posted just for you. Why is it illegal? It's not totally obvious, but it's not too hard either.

CharazardEx999
n9531l1 wrote:
CharazardEx999 wrote:

#5816 updated. please check it

Illegal. The white pawns made five captures, but Black is only missing four men.

yep

DefenderPug2
n9531l1 wrote:

I like it. It gives a place for people who want to draw pictures with chess pieces on a chess board. Now we just have to convince those people to use it and not post here.

But I couldn't find the definition of what makes a position friendly.

The definition is on the first post of the topic….I made it…..

n9531l1
December_TwentyNine wrote:

I don't think the Defender Pug understands what he's been asked to do.

Can someone help me please. I'm having a very hard time figuring out how White got that Pawn Structure on the Queen Side.

I'm wondering whether you understand what DefenderPug2 has been asked to do.

But to answer your request, White got the pawn formation on the queen side by making eight captures by pawns of the eight black men missing from the final position.

n9531l1
December_TwentyNine wrote:

Based off of the information you just gave, the position must be legal, then. I'll have to try it again. It's interesting.

What I gave you was the only way that pawn formation could be achieved, without saying whether or not the position is legal.

n9531l1
DefenderPug2 wrote:
n9531l1 wrote:

But I couldn't find the definition of what makes a position friendly.

The definition is on the first post of the topic….I made it…..

I don't see a definition there. It would look like "A position is considered friendly when _______" and you have to fill in the blank. Since the challenge is to find the friendliest position, you also need to explain how to determine whether one position is more friendly than another.

Ilampozhil25
EvinSung wrote:
repost for defenderpug2

 

 

i can get really far, but the problem is, though black has JUST enough pieces to capture, blacks h pawn cant promote

 

thats a proof game if white doesnt have c1 bishop btw

Ilampozhil25

so, its illegal as blacks h pawn needs 1 more capture than available to promote

n9531l1
Ilampozhil25 wrote:

so, its illegal as blacks h pawn needs 1 more capture than available to promote

Yes. Now you have done what DefenderPug2 was being asked to do.

In #5881, December_TwentyNine misstated the question put to DefenderPug2. The question was "Why is it illegal?" not "Is it legal or illegal?"

n9531l1

By the way, you had the right idea with your explanation, but it was incomplete. The black h-pawn could have promoted, but then the g-pawn would lack the one capture needed to promote.

Andrew67275
Chessman265 wrote:

This is a common trick puzzle, because it appears in a semi-famous book, but is it possible for this position to be reached with white to move?

 

It is possible.

 

 

Ilampozhil25
n9531l1 wrote:

By the way, you had the right idea with your explanation, but it was incomplete. The black h-pawn could have promoted, but then the g-pawn would lack the one capture needed to promote.

oh yeah

anyway black misses a capture

(thatd be via rg3 and rh2 or any other pieces on those squares)

Ilampozhil25
Andrew67275 wrote:
Chessman265 wrote:

This is a common trick puzzle, because it appears in a semi-famous book, but is it possible for this position to be reached with white to move?

 

It is possible.

 

 

thats black to move

 

 

n9531l1
Ilampozhil25 wrote:
n9531l1 wrote:

By the way, you had the right idea with your explanation, but it was incomplete.

oh yeah

I told DefenderPug2 that proving illegality of #5856 is not too hard. You did it by giving a possible proof game, which is one way, but it can be proven without any trial proof games. Here's one proof that's not too hard:

The white pawns need eight captures to get into place, and Black is missing eight men, so every capture White made was by a pawn moving toward the queen side. What happened to the black fgh pawns? The f-pawn could be at d5 after making two captures, and the pawn at d6 made one capture, which only leaves Black two captures to get the g and h-pawns promoted to pieces to be captured by the white pawns. But those two pawns need to make three captures to promote on h1, so one of them is an abducted pawn. (An abducted pawn is one that did not promote, was not captured, and is no longer on the board. Any position that has one is illegal.)

DefenderPug2

I’m so confused….

DefenderPug2

Btw I beat a 800 rated player. We met in 4 player chess teams. Didn’t know I had what it takes. It was unrated. So unfortunately, I did not make a crater in his rating.

Ilampozhil25

im also a beginner and i solved it (almost)

n9531l1

The discussion we've had of it here shows that EvinSung came up with one of the "good" illegal positions: not immediately obvious to an experienced solver, but not too hard for a beginner to solve.

EvinSung