Answers.Body: <p><a href="http://www.theproblemist.org/what-are-chess-problems" rel="noreferrer">This</a> is an excellent source for problems from different range of difficulty, where you can find these types of problems:</p>
  
  <ul>
  <li>Selfmate</li>
  <li>Helpmate</li>
  <li>Reflexmate</li>
  <li>Retrograde Analysis</li>
  </ul>
  
  <p>Which regular chess engines can't solve because solutions are not the best moves. (Actually, worst moves in selfmate problems for example)</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-10T23:32:11.103Z
Answers.LastActivityDate: 2016-01-10T23:32:11.103Z
Answers.UserDisplayName: ferit
Answers.Body: <p>I will do the obligatory retro and proof game plug:</p>
  <h2>Proof games</h2>
  <p>A type of problem where you are to reach the diagram position within a given number of moves.</p>
  <p>A <a href="http://abrobecker.free.fr/chess/IntroductionToPGs.pdf" rel="nofollow noreferrer">good introductory PDF by Alain Brobecker</a>, featuring many &quot;classic&quot; problems that are well-known among the proof game community.</p>
  <p>Jeff Coakley has a lot of shorter (but still tricky) 4-move proof games on <a href="https://chesscafe.com/columns/the-puzzling-side-of-chess/" rel="nofollow noreferrer">chesscafe</a> (although the site put them behind a paywall since 2014, the resourceful reader can probably figure something out...)</p>
  <p>Another simple example (original by me): Reach the position after black's 4th move.</p>
  <pre><code>rnbqkbnr/1ppppppp/8/p7/3P4/8/PPP1PPPP/RNB1KBNR w - - 0 1
  </code></pre>
  <p>Shorter proof games of about 4 to 7 moves are pretty good for regular chess players, and you literally only need to know how the pieces move. Longer ones can go up to 30 moves (for a &quot;normal&quot; long proof game) or even over 180 moves (the longest I know of).</p>
  <h2>Retrograde analysis</h2>
  <p>Given only the diagram position and the fact that it was reached in a legal chess game, determine some feature of the position like side to move, castling rights, en passant rights, whether a piece is promoted...</p>
  <p>An excellent <a href="https://www.janko.at/Retros/PedagogicalCollection.htm" rel="nofollow noreferrer">collection of simpler problems</a> that slowly rise in difficulty.</p>
  <p>A magnificent <a href="https://www.chessproblem.net/viewtopic.php?t=429" rel="nofollow noreferrer">introductory text</a> by Nikolai Beluhov, an excellent composer of such problems. (Link is to a post containing PDF attachment.)</p>
  <p>Another easy example by me again (although the idea is not new): What was the last move played? (I don't even need to give you the side to move for you to solve it.)</p>
  <pre><code>8/8/8/8/8/4PP2/1PPPRKPk/4nQ2 w - - 0 1
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-02-20T14:06:58.350Z
Answers.Text: Thanks for this Remellion. Jeff Coakley is continuing to make new elementary and not so elementary problems which he posts on his fun website: http://www.coakleychess.com/. He is also progressively uploading his old material from ChessCafe, presumably by agreement with them
Answers.UserDisplayName: Laska
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-06-15T11:18:48.900Z
Answers.Text: Spoilers (rot13): 1.q3 n6 2.Dq2 n5 3.Du6 Au6 4.q4 At8 /// -1...Xu1kOu2
Answers.UserDisplayName: Evargalo
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Answers.CreationDate: 2019-02-18T02:37:51.723Z
Answers.LastActivityDate: 2019-05-13T07:50:34.380Z
Answers.LastEditDate: 2020-06-17T09:59:59.497Z
Answers.UserDisplayName: Remellion
Answers.Body: <p>Here is a fun puzzle:</p>
  
  <p>Construct a legal chess game where</p>
  
  <ul>
  <li>white starts with <code>1. a3</code>,</li>
  <li>white delivers checkmate on move 5, and</li>
  <li>the last move is made with the rook that started on <code>a1</code>.</li>
  </ul>
  
  <blockquote class="spoiler">
    <p> Hint: Black takes the pawn on <code>a3</code>.</p>
  </blockquote>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-13T18:17:11.360Z
Answers.Text: This is fun! Thanks for the hint! I'm still working on it, but found other interesting lines. 
  
  1. a3 e5 2. Nc3 Bxa3 3. Rxa3 Ke7 4. Ne4 Nh6 5. Ra5 Rf8 6. Rxe5# 
  1. a4 c6 2. Ra3 Qa5 3. Rc3 Qa4 4. Rc5 Qa1 5. Rc8
Answers.UserDisplayName: Arun J
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-13T18:18:17.527Z
Answers.Text: Tada! Found! 
  
  1. a3 e5 2. Nc3 Bxa3 3. Ne4 Bf8 4. Ra5 Ke7 5. Rxe5# *
Answers.UserDisplayName: Arun J
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-06-15T11:10:02.827Z
Answers.Text: Another version of that puzzle : https://puzzling.stackexchange.com/questions/73474/reconstructing-a-chess-game-1
Answers.UserDisplayName: Evargalo
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-10T22:09:03.520Z
Answers.LastActivityDate: 2016-01-13T17:52:24.090Z
Answers.LastEditDate: 2016-01-13T17:52:24.090Z
Answers.UserDisplayName: Dag Oskar Madsen
Answers.Body: <p>There is a branch of Problem Chess called <strong><a href="https://en.wikipedia.org/wiki/Fairy_chess" rel="nofollow noreferrer">Fairy Chess Problems</a></strong> with all kinds of stipulations.</p>
  
  <p>However, there are specialised programs (e.g. Alybadix or Chloe/WinChloe) to solve fairy chess problems and nowadays problem composers routinely use them to verify the integrity of their creations. For more information, look at <a href="https://en.wikipedia.org/wiki/Software_for_handling_chess_problems" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Software_for_handling_chess_problems</a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2016-01-12T08:14:43.883Z
Answers.LastActivityDate: 2019-02-19T12:47:31.050Z
Answers.LastEditDate: 2019-02-19T12:47:31.050Z
Answers.UserDisplayName: Sir Cornflakes
Answers.Body: <p>Try also Burt Hochberg's <strong>Chess Braintwisters</strong>,
  which often require "thinking outside the box" to a move that is
  logical but illegal (like promoting to a King) and thus would never
  be found by an ordinary chess-playing or problem-solving computer program.
  A couple of examples from that book have already been posted in this forum
  in reply to another question: <a href="https://chess.stackexchange.com/questions/13322/is-there-any-position-where-not-promotingillegally-would-be-the-best-move">Is there any position where not promoting(illegally) would be the best move?</a></p>
  
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Answers.CreationDate: 2018-01-18T17:15:47.410Z
Answers.Text: Dear Mr. Elkies, from your posts I gather you'd potentially be interested in this recent post: https://chess.stackexchange.com/questions/19656/puzzles-that-highlight-the-finiteness-of-the-chessboard
Answers.UserDisplayName: user929304
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-11-26T01:44:27.220Z
Answers.LastActivityDate: 2016-11-26T01:44:27.220Z
Answers.LastEditDate: 2017-04-13T12:48:53.737Z
Answers.UserDisplayName: Noam D. Elkies
Answers.Body: <p>Apart from non-standard problems (fairy chess, retrograde analysis, etc), there also exist particularly difficult regular chess problems which are used for testing chess engines, like Nightmare II. These might not be solvable by some engines/computers. Take a look at <a href="https://chessprogramming.wikispaces.com/Test-Positions" rel="nofollow noreferrer">this list</a> </p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-02-19T12:45:54.327Z
Answers.Text: The site at wikispaces.com has been shut down. Can the link be replaced by something meaningful?
Answers.UserDisplayName: Sir Cornflakes
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Answers.CreationDate: 2016-11-26T17:27:00.247Z
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Answers.UserDisplayName: user1583209
Body: <p>What are some unconventional chess problems that ordinary chess engines can never solve? I'm attaching two examples below so that you can get an idea. My students seem to love these puzzles. I'm researching and learning about it now.</p>
  <p><a href="https://i.sstatic.net/ObQJh.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ObQJh.jpg" alt="Example 1" /></a></p>
  <ul>
  <li><a href="https://www.reddit.com/r/chess/comments/40c4ld/problem_white_to_play_8_consecutive_moves_from/" rel="nofollow noreferrer">Example 2</a></li>
  </ul>
  <p><strong>EDIT</strong></p>
  <ul>
  <li><p>Thanks @ETD for pointing out that it's possible to create programs to solve, at least by brute force solutions to any chess problems. What I mean though is normal chess computers.</p>
  </li>
  <li><p>EDIT 2: I realize that the question is a bit vague. What I really like to know is creative puzzles, which if given to a beginner player should not be solvable by putting it on his computer and running an analysis.</p>
  </li>
  </ul>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2016-01-10T18:08:00.563Z
Comments.Text: In what sense do you mean that a computer can't solve these? I agree that standard chess engines cannot, but that's only because these aren't typical chess problems asking the solver to find the best move in some position, which is what chess engines have been built to do. But one could certainly create a program that solves these two examples, even just by brute force. E.g. for your first example, one need only check all combinations of first 4 moves for Black (and there's not too many of those) to see if one yields a legal sequence ending in mate when paired with those White moves.
Comments.UserDisplayName: ETD
Tags: <problems>
Title: What kinds of unconventional chess problems exist?
ThreadText: # What kinds of unconventional chess problems exist?
  
  (Asked by: username_0 on 2016-01-10)
  
  What are some unconventional chess problems that ordinary chess engines can never solve? I'm attaching two examples below so that you can get an idea. My students seem to love these puzzles. I'm researching and learning about it now.
  
  [![Example 1](https://i.sstatic.net/ObQJh.jpg)](https://i.sstatic.net/ObQJh.jpg)
  
  * [Example 2](https://www.reddit.com/r/chess/comments/40c4ld/problem_white_to_play_8_consecutive_moves_from/)
  
  **EDIT**
  
  * Thanks @username_1 for pointing out that it's possible to create programs to solve, at least by brute force solutions to any chess problems. What I mean though is normal chess computers.
  * EDIT 2: I realize that the question is a bit vague. What I really like to know is creative puzzles, which if given to a beginner player should not be solvable by putting it on his computer and running an analysis.
  
  **Tags:** problems
  
  > **Comments:**
  > **username_1**: In what sense do you mean that a computer can't solve these? I agree that standard chess engines cannot, but that's only because these aren't typical chess problems asking the solver to find the best move in some position, which is what chess engines have been built to do. But one could certainly create a program that solves these two examples, even just by brute force. E.g. for your first example, one need only check all combinations of first 4 moves for Black (and there's not too many of those) to see if one yields a legal sequence ending in mate when paired with those White moves.  
  
  ---
  
  ## 6 answers
  
  ### Answer by username_3 on 2019-02-18. Score: 7
  
  I will do the obligatory retro and proof game plug:
  
  ## Proof games
  
  A type of problem where you are to reach the diagram position within a given number of moves.
  
  A [good introductory PDF by Alain Brobecker](http://abrobecker.free.fr/chess/IntroductionToPGs.pdf), featuring many "classic" problems that are well-known among the proof game community.
  
  Jeff Coakley has a lot of shorter (but still tricky) 4-move proof games on [chesscafe](https://chesscafe.com/columns/the-puzzling-side-of-chess/) (although the site put them behind a paywall since 2014, the resourceful reader can probably figure something out...)
  
  Another simple example (original by me): Reach the position after black's 4th move.
  
  ```
  rnbqkbnr/1ppppppp/8/p7/3P4/8/PPP1PPPP/RNB1KBNR w - - 0 1
  
  ```
  
  Shorter proof games of about 4 to 7 moves are pretty good for regular chess players, and you literally only need to know how the pieces move. Longer ones can go up to 30 moves (for a "normal" long proof game) or even over 180 moves (the longest I know of).
  
  ## Retrograde analysis
  
  Given only the diagram position and the fact that it was reached in a legal chess game, determine some feature of the position like side to move, castling rights, en passant rights, whether a piece is promoted...
  
  An excellent [collection of simpler problems](https://www.janko.at/Retros/PedagogicalCollection.htm) that slowly rise in difficulty.
  
  A magnificent [introductory text](https://www.chessproblem.net/viewtopic.php?t=429) by Nikolai Beluhov, an excellent composer of such problems. (Link is to a post containing PDF attachment.)
  
  Another easy example by me again (although the idea is not new): What was the last move played? (I don't even need to give you the side to move for you to solve it.)
  
  ```
  8/8/8/8/8/4PP2/1PPPRKPk/4nQ2 w - - 0 1
  
  ```
  
  > **Comments:**
  > **username_4**: Thanks for this username_3. Jeff Coakley is continuing to make new elementary and not so elementary problems which he posts on his fun website: http://www.coakleychess.com/. He is also progressively uploading his old material from ChessCafe, presumably by agreement with them  
  > **username_5**: Spoilers (rot13): 1.q3 n6 2.Dq2 n5 3.Du6 Au6 4.q4 At8 /// -1...Xu1kOu2  
  
  ---
  
  ### Answer by username_2 on 2016-01-10. Score: 6
  
  [This](http://www.theproblemist.org/what-are-chess-problems) is an excellent source for problems from different range of difficulty, where you can find these types of problems:
  
  * Selfmate
  * Helpmate
  * Reflexmate
  * Retrograde Analysis
  
  Which regular chess engines can't solve because solutions are not the best moves. (Actually, worst moves in selfmate problems for example)
  
  
  ---
  
  ### Answer by username_6 on 2016-01-10. Score: 5
  
  Here is a fun puzzle:
  
  Construct a legal chess game where
  
  * white starts with `1. a3`,
  * white delivers checkmate on move 5, and
  * the last move is made with the rook that started on `a1`.
  
  > Hint: Black takes the pawn on `a3`.
  
  > **Comments:**
  > **username_0**: This is fun! Thanks for the hint! I'm still working on it, but found other interesting lines.   1. a3 e5 2. Nc3 Bxa3 3. Rxa3 Ke7 4. Ne4 Nh6 5. Ra5 Rf8 6. Rxe5#  1. a4 c6 2. Ra3 Qa5 3. Rc3 Qa4 4. Rc5 Qa1 5. Rc8  
  > **username_0**: Tada! Found!   1. a3 e5 2. Nc3 Bxa3 3. Ne4 Bf8 4. Ra5 Ke7 5. Rxe5# *  
  > **username_5**: Another version of that puzzle : https://puzzling.stackexchange.com/questions/73474/reconstructing-a-chess-game-1  
  
  ---
  
  ### Answer by username_7 on 2016-01-12. Score: 3
  
  There is a branch of Problem Chess called **[Fairy Chess Problems](https://en.wikipedia.org/wiki/Fairy_chess)** with all kinds of stipulations.
  
  However, there are specialised programs (e.g. Alybadix or Chloe/WinChloe) to solve fairy chess problems and nowadays problem composers routinely use them to verify the integrity of their creations. For more information, look at <https://en.wikipedia.org/wiki/Software_for_handling_chess_problems>
  
  
  ---
  
  ### Answer by username_8 on 2016-11-26. Score: 2
  
  Try also Burt Hochberg's **Chess Braintwisters**,
  which often require "thinking outside the box" to a move that is
  logical but illegal (like promoting to a King) and thus would never
  be found by an ordinary chess-playing or problem-solving computer program.
  A couple of examples from that book have already been posted in this forum
  in reply to another question: [Is there any position where not promoting(illegally) would be the best move?](https://chess.stackexchange.com/questions/13322/is-there-any-position-where-not-promotingillegally-would-be-the-best-move)
  
  > **Comments:**
  > **username_9**: Dear Mr. username_8, from your posts I gather you'd potentially be interested in this recent post: https://chess.stackexchange.com/questions/19656/puzzles-that-highlight-the-finiteness-of-the-chessboard  
  
  ---
  
  ### Answer by username_10 on 2016-11-26. Score: 1
  
  Apart from non-standard problems (fairy chess, retrograde analysis, etc), there also exist particularly difficult regular chess problems which are used for testing chess engines, like Nightmare II. These might not be solvable by some engines/computers. Take a look at [this list](https://chessprogramming.wikispaces.com/Test-Positions)
  
  > **Comments:**
  > **username_7**: The site at wikispaces.com has been shut down. Can the link be replaced by something meaningful?  
  
  ---
  
  