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  1. SubscriberBigDoggProblem
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    25 Jul '20 17:36

    White to move. Find the forced win.
  2. SubscriberPaul Leggett
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    26 Jul '20 01:511 edit
    @BigDoggProblem
    This is an awesome position!

    I have been playing with this using Chessbase to move the pieces around while I am binge watching NCIS New Orleans with my wife (which has made me oblivious to what is going on there, to the consternation of my better half).

    White the subject is often brushed over or ignored, endgames abound in tactics.

    Players can get all caught up in positional, strategic considerations, and then find it was all for naught because their opponent's next move can't be met effectively, and the game is over.

    I hope BDP will not mind a few hints.

    Consider the value of a queenside pawn majority, a centralized king, and the possibility of an outside passed pawn.

    Now ignore them, because none of that matters!

    Nice!
  3. Standard memberDeepThought
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    26 Jul '20 07:30
    @BigDoggProblem
    Solution: Reveal Hidden Content
    1. Rd2+ Ke5 {If 1. ... Kc5 2. Rc7+ Rc6 3. Rc2+ wins the rook.} 2. f4+ gf {Not taking changes little.} 3. gf+ Ke6 {3. ... Kxf4 4. Rxd6} 4. f5+ Ke5 5. Re7+ Kxf5 {5. ... Re6 fxe6 is probably worse.} 6. Rxe6 Rxa2+ 7. Ke3 Rxh2 {I think 2 rooks beats a rook and three pawns.}


    Attempt at showing it using the pgn feature embedded in a hidden, but it seems not to work except from the starting position. I left it in so we can copy and paste it later: Reveal Hidden Content
  4. SubscriberBigDoggProblem
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    26 Jul '20 16:562 edits
    DT has it (mostly*) right, and I'm sure PL got it too.

    Stumbled upon this one doing lichess.org puzzles. Liked how a nice idea tumbled out of a seemingly mundane position.

    * Reveal Hidden Content
    White does not have to lose the h2 pawn at the end
  5. Standard memberDeepThought
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    28 Jul '20 04:201 edit
    @bigdoggproblem said
    DT has it (mostly*) right, and I'm sure PL got it too.

    Stumbled upon this one doing lichess.org puzzles. Liked how a nice idea tumbled out of a seemingly mundane position.

    * [hidden]White does not have to lose the h2 pawn at the end[/hidden]
    Ha, it just came up on LiChess, so I had a fairly easy time with that one.

    https://lichess.org/training/63365

    Edit: After reading the hint, Reveal Hidden Content
    Replace 7. Ke3 with 7. Rd2
    I hadn't meant to but I quoted the post and forgot that that reveals hiddens.
  6. Standard memberDeepThought
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    29 Jul '20 13:48
    I had this problem come up (except I interposed black and white) and it illustrates the difficulty I have with LiChess problems:
    White to play and win.

    I'll give people a chance to solve it and then say where I have a problem with how they implement this on LiChess. I'm expecting a variation three moves deep.
  7. SubscriberBigDoggProblem
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    30 Jul '20 01:54
    @deepthought said
    I had this problem come up (except I interposed black and white) and it illustrates the difficulty I have with LiChess problems:[fen]8/6R1/pnk1pN1r/1p2P2p/1Pp3pP/P7/K5P1/8 w - - 0 1[/fen] White to play and win.

    I'll give people a chance to solve it and then say where I have a problem with how they implement this on LiChess. I'm expecting a variation three moves deep.
    Reveal Hidden Content
    1.Ng8 Rh8 2.Ne7+ K~ 3.Ng6+ wins the R
  8. Standard memberDeepThought
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    31 Jul '20 09:47
    @bigdoggproblem said
    [hidden]1.Ng8 Rh8 2.Ne7+ K~ 3.Ng6+ wins the R[/hidden]
    Is the correct answer. But on LiChess you only have to find the first move when the system moves the knight to d5 and you have to find the move Nxh6, so 1. Ng8 Nd5 2. Nxh6, presumably this is Stockfish's Principal Variation. So the problem with the way they set their puzzles is that what the move that Stockfish thinks is best is the one for which the resultant position 20 moves down the line gets a higher score in it's evaluation function isn't necessarily the most challenging to a human. In the case of this problem the point lies in the variation you gave. The first move Nb8 was my first thought, but I realised the rook isn't trapped, and then I wondered about checkmate but the knight blocks the rook's influence over the seventh rank. Then I managed to synthesize the two ideas and got it. The difficult move to find is the second one, 2. Ne7+, but one only needs to find the first one to think one's solved the problem on LiChess. Assuming they rate their puzzles using the same method that players are rated then puzzles like this will tend to be underrated as there's people who solve the whole problem like you and people who solve it by getting the first move. There, gripe over.
  9. SubscriberBigDoggProblem
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    31 Jul '20 23:47
    @deepthought said
    Is the correct answer. But on LiChess you only have to find the first move when the system moves the knight to d5 and you have to find the move Nxh6, so 1. Ng8 Nd5 2. Nxh6, presumably this is Stockfish's Principal Variation. So the problem with the way they set their puzzles is that what the move that Stockfish thinks is best is the one for which the resultant position ...[text shortened]... ve the whole problem like you and people who solve it by getting the first move. There, gripe over.
    Probably they have a bot finding the puzzles in the first place. Hard to make a bot that finds the best "educational" variation.
  10. Standard memberDeepThought
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    02 Aug '20 21:52
    @bigdoggproblem said
    Probably they have a bot finding the puzzles in the first place. Hard to make a bot that finds the best "educational" variation.
    Agreed, but they could have a way of alerting that particular situation so a moderator can make a decision about the best line. As things stand there's just a "do you like this" vote, which doesn't cover that particular base.
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