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| (21) Posted by Joost de Heer [Friday, Jul 28, 2023 09:06] |
I don't know if it's possible in this position, but would e.g. exchanging one white pawn with a white officer be considered a cook? All 16 pieces are present, it's just that one of them is a promoted pawn, and the stipulation doesn't explicitly forbid that.
EDIT: Oops, miscounted, there are already 8 pawns in the diagram position. But this could be a cook risk if you need to add a white pawn.
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| (22) Posted by Joaquim Crusats [Friday, Jul 28, 2023 09:11] |
The position can be modified with many promoted units on the board. This is why in the puzzle version the eight wPs are on the board.
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| (23) Posted by James Malcom [Saturday, Jul 29, 2023 04:40] |
Here's a stab at the pawn per file challenge. The next hard part is no promoted Black pieces, which very likely will require more than five.
 (= 16+5 )
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| (24) Posted by Ulrich Voigt [Monday, Jul 31, 2023 19:39] |
How about this:
 (= 16+4 )
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| (25) Posted by Ulrich Voigt [Monday, Jul 31, 2023 20:22] |
I think I can save another Black piece:
 (= 16+3 )
We need Ba1 to guard g7 and Qf2 to protect wK. To prevent an illegal double check (no en passant tricks here), we need Pf3. To guard the squares around bK, we need Rh6, Bc4, Nc8, Pe4, Ph4, and further Pg6 to prevent another illegal double check. To block the black pieces, we need Nb4, Pa4, Pb5, Pc2, Pd3. Finally, Rb3 is the only piece that can deliver the checkmate.
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| (26) Posted by Joaquim Crusats [Monday, Jul 31, 2023 20:45] |
This seems to allow, regardless of the positions of the pawns, a (16+3) with two bRs only:
 (= 16+3 )
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| (27) Posted by Ulrich Voigt [Monday, Jul 31, 2023 20:59] |
By guarding f5 with a wN you can achieve 8 pawns on 8 different files:
 (= 16+3 )
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| (28) Posted by Ulrich Voigt [Monday, Jul 31, 2023 21:05] |
16+2:
 (= 16+2 )
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| (29) Posted by Joaquim Crusats [Monday, Jul 31, 2023 21:56] |
(16+2) it is!
What about placing the wP that gave the check on c5?
Then, like in post (20), although with no subtle Try:
 (= 9+2 )
Add white pieces to get a position in which all 16 white units are essential for a legal mate to the black king.
Is it unique?
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| (30) Posted by Mu-Tsun Tsai [Tuesday, Aug 1, 2023 01:43] |
Guess we were too into the idea of ep that we overlooked such matrix. Congrats Ulrich!
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| (31) Posted by James Malcom [Tuesday, Aug 1, 2023 07:54] |
Now we need to look into achieving checkmate without a king present...
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| (32) Posted by Joost de Heer [Tuesday, Aug 1, 2023 08:04] |
Never mind.
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| (33) Posted by Arno Tungler [Tuesday, Aug 1, 2023 08:33] |
At least a black rook is sufficient with the new idea…
 (= 16+2 )
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| (34) Posted by Joaquim Crusats [Tuesday, Aug 1, 2023 08:43] |
@(33) Can't the wPe6, wPc2, wPc4, and wSb2 be removed?
A bR may be enough, but probably this will require new trickery.
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| (35) Posted by Georgy Evseev [Tuesday, Aug 1, 2023 10:03] |
@(33)
At least Bd2 is obviousy not required.
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| (36) Posted by Arno Tungler [Tuesday, Aug 1, 2023 10:23] |
You both are of course right. Need to think before post…
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