possible or impossible?

piphilologist

Surely that is illegal because there is no way the rook can get to b3 without white already being in check?

zuup

So we have to reach this position with whatever white piece on a1.

The pawn in b2 come from g7. He has to take on f6, e5, d4, c3 and b2. So 5 times.

White is missing 2 rooks, 2 bishops, queen and 1 knight. One less to promote. So 5 pieces remaining.

The problem is white can't developp his white bishop.

I think it's not possible.

JamieKowalski

Very nice deductive work, zuup!

Now tell me if this version changes anything:

Adriandmen

Now it is possible Laughing

zuup

My argument become invalid! 0_o

But I don't have time to look more at it.

s0030135

Yes,possible:

 

JamieKowalski

Good work, s0030135! 

You guys are demolishing my puzzles.

andrewjmen

don't forget Shoopi's puzzles and here's one of my own:

piphilologist
andrewjmen

you're right piphilologist!

andrewjmen

this one looks the same and is as easy as the previous one

shoopi
piphilologist wrote:

So there must be trick that I'm missing.

Yes, there is!

Well, not really a "trick", but there is a way for white to have a legal last move with his king. You need to look back more than one move, though. You're thinking, if a square is threatened by at least 2 black pieces, there's no way that the white king came from that square. But it is possible - black had a discovered double check, which is the only possible sequence leading to the final position.

piphilologist

I still don't get it. If there wasn't a knight on h7 then N on e7, K on f8, 1...Ne7-g6++ 2.Kg7 but in the diagram f8 would be impossible triple check. The only other possibility is f7, but again it is impossible double check. I really don't see how either position can be legal

shoopi

What about g8?

kyriazis

The first one is possible, all you need is 6 black minor pieces sacrificed to move the pawns into position like that for white and 1 more to get another white bishop on the black square

piphilologist
shoopi wrote:

What about g8?

What? I'm talking about diagram 2, which you say is legal. If it's black to move white has just moved; he can't have moved from a square that has a piece on. Like I said earlier it would be possible if it was white to move because of B on c4 and N on d5 and K on g8, 1...Nf6++ 2.Kg7 Bg8

Did you put "Black to move" by mistake?

shoopi

Oh right, I had looked at the position again and I have mislead you a bit before. Turns out white actually can have a last move with a pawn. Sorry for the confusion Embarassed

piphilologist

Oh yeah I get it now thats for clarifying that.

5 spare white pieces

the d-pawn took a piece on the e-file and the f-pawn

c-pawn took a piece on b2

at least one pawn queened on a1 to another dark bishop therefore a-pawn x b x a and b-pawn x a

therefore a3 played first, then a and b pawns queen, then b3 and c-pawn queens

therefore only 1 spare pawn move (a3-a4)

So the last moves were 1...Nd5-f6++ 2.Kg7 Bg8 3.a4

and position 1 is illegal because Rook prevents the bishop coming from c4

nice position :)

shoopi

That's right! Finally that one is solved hehe...

To celebrate, here are two easier puzzles, composed by me.

Can white castle?

piphilologist

1st puzzle white can castle, white h-pawn take black rook and promotes on g-file, black g-pawn takes 5 pieces (Q,R,N,dark-squareB,promoted pawn) promotes on b1 with White Knight on d1, black B goes to c1 freeing the knight which goes to b1, black bishop goes back to f8

2nd white can't castle, black h-pawn takes 5 white pieces (Q,R,B,N,c-pawn) promotes when the white N is on d1 but white N can't get to b1