i think there's only one... 1.Rd1..[insert any black move here] 2.Rd8#
the other variations fail: 1. Rxa4 .. e3! (2.Ra8+ .. Bxa8), 1. Rb1..Nb2! (or Nb6!), 1.Rc1..Nc3! (or Nc5!). and if Ra2, Ra3, or any other white move, black can just push his bishop to g2 or f3, or move a pawn, so long as he retains his knight at a4 he avoids mate in 2.
edit: and note that black has no mating solutions, so even though it's not explicitly stated that it's a white mate in 2, it does not present any issues
Originally posted by AetheraelIs that your final answer?
i think there's only one... [b]1.Rd1..[insert any black move here] 2.Rd8#
the other variations fail: 1. Rxa4 .. e3! (2.Ra8+ .. Bxa8), 1. Rb1..Nb2! (or Nb6!), 1.Rc1..Nc3! (or Nc5!). and if Ra2, Ra3, or any other white move, black can just push his bishop to g2 or f3, or move a pawn, so long as he retains his knight at a4 he avoids mate in ...[text shortened]... though it's not explicitly stated that it's a white mate in 2, it does not present any issues[/b]
Originally posted by heinzkatmaybe i'm missing something but what stops the black bishop from surviving through the e-pawn capturing to f6, the h-pawn capturing to g6, and then bB moves to a3, c1, and h6 before blacks pawn continues to g5? then i count only 13 black pawn captures...
One [1. Rd1 ~ 2. Rd8#]. bBf8 was captured at home; bBh6 comes from a promoted pawn on a1 (from a7), so the a1 Rook must have moved; if the a7 pawn promoted on c1, that would have required 15 captures.
i'm still not good at these problems though so if you have some insight it would be much appreciated! 🙂 i really like the logic behind the retro analysis games
edit: in rereading i'm not very clear in my question. why must the black DS bishop have been captured at home, rather than moving in a legal order to reach h6 within the current pawn formation? am i missing a key issue in which this order of moves is impossible?
Originally posted by AetheraelThe Rook on g6 I think.
maybe i'm missing something but what stops the black bishop from surviving through the e-pawn capturing to f6, the h-pawn capturing to g6, and then bB moves to a3, c1, and h6 before blacks pawn continues to g5? then i count only 13 black pawn captures...
i'm still not good at these problems though so if you have some insight it would be much appreciated! 🙂 i really like the logic behind the retro analysis games
Originally posted by heinzkatoh of course. very good thanks! and great problem swissgambit - i always love the subtleties of these constructions that seem obvious at first, have some sort of complicating/"oh i forgot to consider the possibility of ___"-twist, and yet are ultimately entirely concise and sound.
The Rook on g6 I think.
Originally posted by heinzkathaha... well it at least contradicted my proposed move order, in that black's a-file rook would not be able to sneak in there behind both black's DS bishop AND the h-pawn capturing at g7 followed by g7-g6. and i can't think of any other move configuration that would allow the pieces to be setup that way, so am more inclined to agree that the black bishop is a result of an a1 pawn promotion, since as you said a c1 promotion would require 15 pawn captures and thus make white's rook impossible.
Probably this is still incorrect but OK, I'm glad it sort of sounded convincing to you 🙂
Team SOLV'D. I will only add a supplement on why Bh6 must be promoted.
Consider this part of the structure. Which of these pieces moved last? There is only one that can even retract a move - Pf6 - and he must have come from e7. This proves conclusively that Bh6 could not have come from f8, but is promoted.
The answer is one solution - 1.0-0-0? is illegal per the reasoning here and in posts above.