Wow, I'm not even sure where to start with this one. I can account for all six of Black's pieces being captured by White's pawns on the King-side (neither the a nor b pawns have captured), and one capture of a White piece by Black's a pawn. What that tells me about the Knights I havn't figured out yet.
Deductive Puzzle #24
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Jun 29, 2009
0
#3
Black's c-pawn must have promoted, in order to be captured on the kingside.
we start by back tracing our moves.
White's last move? If it was N move to unveil check, black could not have made any move before that! So white must have played fxe6+
Why could black not have made any move before Na1+ (or Na3+ if that's not actually Black's Knight)? The Black King could have been on h7 long before the one of Bishop was ever on h8 or the pawn was on h5.
Jun 29, 2009
0
#6
Actually, white's last move MUST have been to "unveil" check with a knight move, as there's no way it could have been fxe6+ because there aren't enough black pieces missing for that to be possible.
Jun 29, 2009
0
#7
If the knights were as they are shown, the position would be impossible, because white's last move couldn't have been Na1+, as black had no legal move before this which brought about that position, and it can't have been fxe6+ because there aren't enough black pieces gone. Therefore, white's last move must have been Na3+ allowing for black's previous move to be Na1 (from b3).
Actually, thinking about it again, white could have just played Na1+ because there are two possibilities of what black played before that (but only two): bxa6 and gxh6. If we could discount these possibilities though, we'd have the answer
Jun 29, 2009
0
#8
Interesting.... Black's Bishop is a promoted one. Following from WW's analysis, Black's last move MUST have been bxa6, which means the Bishop couldn't have escaped from c8.
Jun 29, 2009
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#10
omnipaul wrote:
Interesting.... Black's Bishop is a promoted one. Following from WW's analysis, Black's last move MUST have been bxa6, which means the Bishop couldn't have escaped from c8.
Well, either black's last move was bxa6 OR the a1 and a3 knights are what's switched, and black's last move was Na1 (from b3)
Good catch on the h6 thing
Jun 29, 2009
0
#11
Got it. The black light squared bishop can't have been taken on c8, as either a) it is original and on g8, and all of black's missing pawns were captured on the kingside either before or after promoting or b) a pawn was promoted as a light-squared bishop and then moved to g8. If that's the case then in order for white's pawns on the kingside to get where they were, then the c8 bishop had to have been taken on the kingside.
Therefore, the a1 and a3 knights have their colours switched.
Jun 30, 2009
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#12
But how could Black's last move have been a Knight move from b3 to a1? That means White would have left himself in check for a move.
Jun 30, 2009
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#13
Right you are. Man, I must have been really tired last night. I'm now stumped... the position seems impossible to me, for the reasons I've listed above.
Jun 30, 2009
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#14
Start with material:
* Black has lost 2 pawns, 2 rooks, a queen and a bishop (white has made 6 captures)
* White has lost 1 pawn, 2 rooks and a queen (black has made 4 captures)
Then captures:
* White must have made 6 captures (i.e. every black piece) with pawns to get the pawn structure. The c-pawn could not have been captured by a white pawn.
* The pawn on e6 must have captured from the d-file - it takes too many moves for that pawn structure if it was ever on the f-file
This means white's last move must've been Nb2-a1+ - and so that knight definitely started out as a white knight. Which means the knight that changed colour is on d8.
Jun 30, 2009
0
#15
b8 knight
The only way the black knight could have got to b8 is via c6 as the d7 pawn has not moved yet. It must have moved during the game to let the rook out (as we know the rook was captured by a white pawn).
g7 bishop
Must have got to g8 via h7 (f7 pawn has not moved). This manouevre must have happened before the white bishop got to h8.
Captures
Black has captured 4 white pieces. One piece (not a pawn) was captured on a7. The other 3 were captured elsewhere - possibly by the c-pawn
Want a hint...?
Hmm, my vote is for no.
Jun 30, 2009
0
#18
texaspete wrote:
Start with material:
* Black has lost 2 pawns, 2 rooks, a queen and a bishop (white has made 6 captures)
* White has lost 1 pawn, 2 rooks and a queen (black has made 4 captures)
Then captures:
* White must have made 6 captures (i.e. every black piece) with pawns to get the pawn structure. The c-pawn could not have been captured by a white pawn.
* The pawn on e6 must have captured from the d-file - it takes too many moves for that pawn structure if it was ever on the f-file
This means white's last move must've been Nb2-a1+ - and so that knight definitely started out as a white knight. Which means the knight that changed colour is on d8.
Is there a reason that the move can't have been Nb2-a3+?
TheGrobe wrote:
Hmm, my vote is for no.
I'll keep it vague then. I see an assumption that looks right at face value, but isn't.
One assumption I see is that the Black c-pawn can't have been captured before promotion:
Why couldn't it have captured over to the e-file to be captured by White's d-pawn? It requires two captures, and only one of the others can be definitively accounted for (bxa6) so it doesn't need to have been promoted.
Two Knights have traded Armor! Thus, one of the White Knights looks Black, and one of the Black Knights looks White! Which two Knights switched colors?