Is this position legal?
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Impossible bishop and knight checkmate!
Not impossible.
Retrograde analysis problem.
Add a black Rook if this is a mate. Is this a legal position with that rook?
ZhenyaChaynikov wrote:
Retrograde analysis problem.
Add a black Rook if this is a mate. Is this a legal position with that rook?
It would appear +bRg1 is a legal position.
At the start of my PGN, we have 7 black pawn captures balanced by 7 missing white units. wRa1 can get back there [thankfully, the P is at a4, not a3, where it would prevent the retraction.] Therefore, the position is legal.
I think impossible mate
testlmao wrote:
I think impossible mate
You "think"?! You needed "thought"?!
Where did the wBh7 come from?
BigDoggProblem wrote:
testlmao wrote:
I think impossible mate
You "think"?! You needed "thought"?!
Where did the wBh7 come from?
It probably came from the neighbor's board. Bishops now travel diagonally through boards.
BigDoggProblem はこう書きました：
Where did the wBh7 come from?
Legal in Alice (-1. B~h7 from B board), Patrol (-1. Kg6), Lortap (not even check) and Madrasi (-1. KxBg6) I think? 
I kind of went deep down the rabbit hole...
I think it is a legal, but how prove that?
Me no pro but me think legal
Ah, that one. Veisberg and Ya'akov 1948. Nice problem. Stumped me when I was new to retros. Those who've never seen this type of problem should definitely try and figure out how to make a game leading to that position.
SPOILER (unless I'm making mistakes)
What was the last move and who did it?
It cannot be white since this move would have been a3 (the only move) and black would have been in check just before making an illegal move
If it is black, then the last move must have been a king's move (otherwise we have a similar position as in the previous sentence with the last move being a3 by white). Black kings comes from c2 and again, the white move before black's king move would have been a3. But there is no way the black king can be behind white pieces like that, how could he have entered the defence, pawns haven't moved. Thus this position is illegal.
Very cool puzzle btw
Jul 26, 2018
0
#1456
- Number 2 is legal and interesting position, number 1 is a don't legal, pawns don't move.
@Colin20G - Wrong, the position is legal. The last move white made (regardless of whose turn it is) doesn't have to be a2-a3. Try again?
This is really troublesome. Black needs to capture pieces 3 times in order to get this pawn structure but white could only move 3 pieces past his pawns (including the promoted pawn). Another sequence would have been Ka2-a1 Kc2 b3 but how is the black bishop on c4?
I'll try to provide a PG but it is yet to be found.
Not a proof, but the necessary analysis.
The White b1-knight could be (was) from the White f- pawn promotion. In that case, the missing original two knights and queen add up to three White captures away from row 1 by Black - necessarily by the three pawns. And, of course, the White king and queen moved through the f2 square and the other White pieces were captured in situ. White's last move resulted in his moved piece being captured.
I like it.
Fixed the position