# possible or impossible?

• 3 years ago · Quote · #181
piphilologist wrote:

52 , the white first-rank-shifting was unneccesary but I had put it in anyway and didnt feel like re-entering the game

Haha brilliant! switching rooks to opposite wings. Now that's creative thinking.

• 3 years ago · Quote · #182
piphilologist wrote:

For #163 the last white move must have been a pawn move (or for #1 1.Rh5+ N4xh5# but I doubt the composer left any spare white pieces)

In position 2 Black can play N4h5# with the same position as #1 except for a rook. But I have no idea why f5 would be a legal rook position and c4 not, I suppose I'll only figure out if i do loads of analysis of the position

Could white have moved a pawn on his last move though? This can be easily determined if you try to actually obtain all of those promoted pieces for black.

And if white couldn't have, what could have been his last move? What was the last sequence?

Let me know if you're still working on it, because it seems at the moment like you're the only one :)

• 3 years ago · Quote · #183
shoopi wrote:
piphilologist wrote:

For #163 the last white move must have been a pawn move (or for #1 1.Rh5+ N4xh5# but I doubt the composer left any spare white pieces)

In position 2 Black can play N4h5# with the same position as #1 except for a rook. But I have no idea why f5 would be a legal rook position and c4 not, I suppose I'll only figure out if i do loads of analysis of the position

Could white have moved a pawn on his last move though? This can be easily determined if you try to actually obtain all of those promoted pieces for black.

And if white couldn't have, what could have been his last move? What was the last sequence?

Let me know if you're still working on it, because it seems at the moment like you're the only one :)

I have also tried that one,but it seemed that black could not promote to a dark square bishop if white hadn't played a4 and b3 before that, since if only b3 was played,one more white piece will be required to have it promoted on a1 or c1,while the f and h pawns can't promote to a dark sqaure bishop.Therefore white's last move seems to be a king move,but I cannot find a square for white king to come from which was not already protected by a black knight.But perhaps I was missing something.

• 3 years ago · Quote · #184

There are 5 white pieces that can be captured (Q,R,R,N,black bishop)

The d-pawn made 2 captures, the other pawns 1.

the b-pawn must have moved to allow cxb2

If the a-pawn was on a3 until the previous move then it must have moved before the b-pawn to allow bxa2, but the b-pawn must have moved first to allow axb2.

Contradiction, therefore the a-pawn was on a4 and b-pawn on b3 and the last white move was not a pawn move

White has just moved, his last move was not a pawn or knight move therefore it was a king move.

If this was being played 20 years ago then it would have been easily possible because a king was only considered in check if attacked by 1 or 2 pieces. So it would not have been in check on f8. But under the current rules it is in an impossible triple check on f8.

So there must be trick that I'm missing.

(if it was white to move it would be possible with say B on c4, N on d5, K on g8, 1...Nd5-f6++ 2.Kg7 Bg8)

• 3 years ago · Quote · #185

Here's a fresh one for you all. Double-check your answers... there are several tricky bits here.

• 3 years ago · Quote · #186

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

• 3 years ago · Quote · #187

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.

• 3 years ago · Quote · #188

Very nice deductive work, zuup!

Now tell me if this version changes anything:

• 3 years ago · Quote · #189

Now it is possible

• 3 years ago · Quote · #190

My argument become invalid! 0_o

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

• 3 years ago · Quote · #191

Yes,possible:

• 3 years ago · Quote · #192

Good work, s0030135!

You guys are demolishing my puzzles.

• 3 years ago · Quote · #193

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

• 3 years ago · Quote · #194
• 3 years ago · Quote · #195

you're right piphilologist!

• 3 years ago · Quote · #196

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

• 3 years ago · Quote · #197
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.

• 3 years ago · Quote · #198

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

• 3 years ago · Quote · #199