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Posers and Puzzles

Posers and Puzzles

  1. 02 May '08 06:30
    Black

    White

    White to play. Mate in 60. Composer will be given later.
  2. 02 May '08 13:58 / 2 edits
    Quite easy, actually (to solve, not to compose, of course). (ten minutes later) SOLV'D !
  3. Standard member SwissGambit
    Caninus Interruptus
    02 May '08 17:39
    Originally posted by heinzkat
    Quite easy, actually (to solve, not to compose, of course). (ten minutes later) SOLV'D !
    http://www.timeforchess.com/board/showthread.php?threadid=89737&page=19#post_1719080

    Good to see your confidence is improving.

    Solution PM'ed [to Jirakon].
  4. 02 May '08 19:49
    SOLV'D (heinzkat, SwissGambit)

    Composed by Dr. Karl Fabel.

    Oh, and I saw this in a Mensa book; I didn't mean to be repetetive.
  5. Standard member SwissGambit
    Caninus Interruptus
    02 May '08 21:34
    Originally posted by Jirakon
    SOLV'D (heinzkat, SwissGambit)

    Composed by Dr. Karl Fabel.

    Oh, and I saw this in a Mensa book; I didn't mean to be repetetive.
    Actually, I think the Mate in 60 I just linked is also by Fabel [with help from another composer]. It looks like someone saw this idea and helped him improve it [in this one, wK visits the same triangulation square several times; in the linked one, it is a different square each time].
  6. 02 May '08 21:41
    Interesting - that one is a lot more difficult though (this one is quite natural)
  7. Standard member SwissGambit
    Caninus Interruptus
    03 May '08 00:06
    Originally posted by heinzkat
    Interesting - that one is a lot more difficult though (this one is quite natural)
    Well, it is more difficult to play defense for Black in the other one, but for White, the idea is exactly the same.
  8. 03 May '08 14:20 / 1 edit
    Originally posted by Jirakon
    Black
    [fen]8/4K3/4NN2/p3p3/rnp1p3/1pk5/bp1n4/qrb1N3[/fen]
    White

    White to play. Mate in 60. Composer will be given later.
    THIS IS THE SOLUTION - IF YOU STILL WANT TO TRY AND SOLVE IT DON'T READ THIS.

    Brilliant puzzle, I thought. But not too hard to solve once you get the key ideas.

    First, observe that black is very nearly in zugzwang. Most of his pieces just can't move at all. He has two pawns on the e-file which can lose up to four moves between them, and he has a rook on a4 which can shuffle back and forth. The only other pieces that can move are the knights, but any move by the b-knight except a check allows Nd5 mate (and he can't check on d5 because of Nxd5 mate), and any move by the d-knight except a check allows Ne4 mate (or Nxe4 mate, when there is a pawn there).

    Therefore, all black can do is shuffle back and forth with the rook, or push the e-pawns.

    Equally, white has to keep black in the stranglehold. If, for example, he allows the b-knight to move with check (except to d5) then this will release the black king, black will unravel and his extra material will win.

    So white's plan is to get his king in to b5, capture the rook (or force the a-pawn to go to a4, trapping the rook forever), and then force the e-pawns to move till they run out of squares. As soon as he does that one of the black knights will have to move and he can mate as above.

    But to avoid both the illegal squares and the squares from which he can be checked, white's king has only one suitable approach route: d7-c8-b7-b6-b5. If he follows this path immediately, and the rook shuffles back and forth, the rook will be at a4 when the king arrives at b5, so the rook retreats to a3, the king will then have to retreat (no other move) and the rook can go back to a4. To avoid this, white needs to get to b5 in an even number of moves.

    So first, white loses a move by Ke8, and then follows the path d7-c8-b7-b6-b5. Now (if the e-pawns haven't moved) when he arrives at b5, the rook is at a3 already, and cannot move. One of the e-pawns has to move (a4 just accelerates the inevitable zugzwang). Now white has to retreat, and has to triangulate to lose a move. The only way to do that is to follow the above path back to e8, and then go f8-f7-e8 to lose a move. He then proceeds back to b5 following the same path as above.

    He has to visit b5 using this method four times to force four e-pawn moves. Then on the fifth visit, black is out of luck. He has to lose the rook or trap it, and then he will be out of knight moves.

    If black moves the e-pawns any earlier than the above it just accelerates the demise. Every time one moves, white traces back to f8 to triangulate.

    So the 60-move line is as follows. Unless otherwise stated, all black's moves are shuffling the rook between a3 and a4.

    White plays Ke8-d7-c8-b7-b6-b5 (6 moves)
    Black rook now on a3 so forced to play e3
    White plays Kb6-b7-c8-d7-e8-f8-f7-e8-d7-c8-b7-b6-b5 (13 moves)
    Black rook now on a3 so forced to play either e4 or e2
    White again plays Kb6-b7-c8-d7-e8-f8-f7-e8-d7-c8-b7-b6-b5 (13 moves)
    Black rook now on a3 so forced to play either e4 or e2 (whichever not played last time).
    White again plays Kb6-b7-c8-d7-e8-f8-f7-e8-d7-c8-b7-b6-b5 (13 moves)
    Black rook now on a3 so forced to play e3.
    White again plays Kb6-b7-c8-d7-e8-f8-f7-e8-d7-c8-b7-b6-b5 (13 moves)
    Black is out of pawn moves, so forced to play either a4 (trapping the rook
    That is 4x13 + 6 = 58 moves. Then we have either 58..Ra4 59 Kxa4 or 58..a4 59 Kb6. Either way, now a knight has to move, and white mates, as discussed above.
  9. Standard member SwissGambit
    Caninus Interruptus
    03 May '08 17:56
    Originally posted by d36366
    [b]THIS IS THE SOLUTION - IF YOU STILL WANT TO TRY AND SOLVE IT DON'T READ THIS.

    Brilliant puzzle, I thought. But not too hard to solve once you get the key ideas.

    First, observe that black is very nearly in zugzwang. Most of his pieces just can't move at all. He has two pawns on the e-file which can lose up to four moves between them, and he has a ...[text shortened]... 58..a4 59 Kb6. Either way, now a knight has to move, and white mates, as discussed above.[/b]
    I see nothing wrong with 1.Kd6 - this also loses a tempo, and there are no N checks thanks to Pe4/c4.
  10. 04 May '08 19:10
    Originally posted by SwissGambit
    I see nothing wrong with 1.Kd6 - this also loses a tempo, and there are no N checks thanks to Pe4/c4.
    That also works, I think. The follow up is the same - the second move will still be Kd7, which takes us to the same position. Thus, it's another solution, no better or worse. Do you agree?
  11. Standard member SwissGambit
    Caninus Interruptus
    04 May '08 20:48
    Originally posted by d36366
    That also works, I think. The follow up is the same - the second move will still be Kd7, which takes us to the same position. Thus, it's another solution, no better or worse. Do you agree?
    Yeah. However, the composer should have made sure only one first move works - having two that work is a glaring defect.
  12. 05 May '08 08:12
    Originally posted by SwissGambit
    Yeah. However, the composer should have made sure only one first move works - having two that work is a glaring defect.
    Well, I still think it's a neat puzzle, but then I've never really understood why problem people care so much about that sort of thing.

    The odd thing is, if you put the king on f7 and the rook on a3, and stipulate mate in 61, then I think you do have a unique first move in Kf8, equally unintuitive, and a longer number of moves. Have I got that right? Wouldn't that make it a "better" problem, according to the criteria people use to judge these things? If so, it is curious that the composer missed this, after having obviously put quite a lot of work into the composition.
  13. Standard member SwissGambit
    Caninus Interruptus
    06 May '08 03:58
    Originally posted by d36366
    Well, I still think it's a neat puzzle, but then I've never really understood why problem people care so much about that sort of thing.

    The odd thing is, if you put the king on f7 and the rook on a3, and stipulate mate in 61, then I think you do have a unique first move in Kf8, equally unintuitive, and a longer number of moves. Have I got that right? Woul ...[text shortened]... composer missed this, after having obviously put quite a lot of work into the composition.
    You just showed why - why give the appearance of two solutions when it's so easy to nudge a couple units and fix it?