Answers.Body: <p>Yes indeed, n corresponds to king, as we need two kings of a different color to have a legal chess position.</p>
  
  <p>Also, as you give, h = pawn, as otherwise we would have a pawn on the first or last rank, which would be illegal.</p>
  
  <p>Consider i.
  It cannot be a queen, as both kings would be in check.
  It cannot be a knight, as the "i" on a2 would give check. There is no legal way where "knight a2 check" is the last move.
  It cannot be a bishop, as the "I" on a5 would give check. There is no legal way where "bishop a5 check" is the last move.
  Therefore, i = rook.</p>
  
  <p>We see that the king on c3 is in check by the rook on c1. Therefore, g cannot be a queen or a bishop, because there is no legal way to obtain the resulting position.
  So, g = knight.</p>
  
  <p>The "K" on b8 should not give check to the king on b6.
  Therefore, k = bishop and t = queen.</p>
  
  <p>[However, the resulting position seems to be impossible to achieve too...
  As far as I can see, the puzzle has no solution.]</p>
  
  <p><strong>Edit: the resulting position is indeed possible</strong>, see the answer of Glorfindel.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-06-22T14:13:02.753Z
Answers.Text: You're welcome and thank you for the question.
Answers.UserDisplayName: Maxwell86
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-06-22T12:40:46.693Z
Answers.LastActivityDate: 2017-06-22T18:37:43.833Z
Answers.LastEditDate: 2017-06-22T18:37:43.833Z
Answers.UserDisplayName: Maxwell86
Answers.Body: <p>This is a basic example of an orthodox retro form which has been taken to a new level over the last year by Ukrainian composer Andrey Frolkin and Canadian Jeff Coakley. I recently acquired a lovely landscape painting by Andrey's wife, Nina, which contains an embedded rebus by Andrey, who I bet authored the problem OP posted!</p>
  
  <p>Although Maxwell's excellent proof relied at a couple of place on the edge of the board preventing retro-movement, this is not actually necessary. Shift all the pieces one square to the right (except for h on h2), and the problem remains sound (and in my opinion slightly superior :D )!</p>
  
  <p>Proof: first count the pieces.
  <code>
        K N I G H T
  Upper 1 1 1 0 0 0
  Lower 0 1 2 2 1 1
  </code></p>
  
  <p>So N is king and by examining first and last ranks, H is pawn. Observe that whatever I represents, one instance is giving check to the enemy king. So any other checking unit implies a double check. So G is not a diagonal unit (bishop or queen), and K is not an orthogonal unit (rook or queen), since the resulting double checks are impossible. And I is not queen, or both kings would be in check!</p>
  
  <p>So by elimination the queen is represented by T and we do have double check. So I can only be rook, and the position is achieved through promotion. Hence lower case is Black. G must be knight so by elimination K is bishop.  </p>
  
  <pre><code>[title "Frolkin? version Laska rebus: solution"]
  [fen "2B5/8/2k5/1R6/2n5/3K4/1r5p/1q1r1n2 w - - 0 1"]
  </code></pre>
  
  <p>and Black's last move was c2xd1=R++</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-10-12T10:44:39.323Z
Answers.Text: So, what was the last move? That the white King walked illegally into that double check? "i" is Bishop, "K" is knight. "g" is rook
Answers.UserDisplayName: LocalFluff
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-10-12T11:16:05.890Z
Answers.Text: @LocalFluff: Thanks for the question. Last move was black pawn on c2 capturing something on d1 and promoting to rook check, also discovering check from queen. The solution would **have** to be something like this to allow white and black to be distinguished. If I,K&G are as you suggested, then both kings are in check: wKd3 from bQb1 and bKc6 from wBb5.
Answers.UserDisplayName: Laska
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-10-12T01:42:06.670Z
Answers.LastActivityDate: 2017-10-12T07:45:50.207Z
Answers.LastEditDate: 2017-10-12T07:45:50.207Z
Answers.UserDisplayName: Laska
Answers.Body: <p>Assume the board is in it's usual position (the bottom row is the first row) then this is the solution:</p>
  
  <pre><code>[FEN "1B6/8/1k6/R7/1n6/2K5/r6p/q1r1n3 - - - 0 1"]
  </code></pre>
  
  <p>and Black's last move was b2xc1R++.</p>
  
  <p><sub>I could write an explanation here about I came to this result, but it would essentially be copying @Maxwell's answer. I didn't use it, though.</sub></p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-06-22T12:53:45.400Z
Answers.Text: Heh, I even thought about the possibility of multiple queens by promotion, but this is quite an interesting twist. Well done.
Answers.UserDisplayName: Annatar
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-06-22T18:35:14.293Z
Answers.Text: I assume `++` is a checkmate symbol, but is it really a checkmate? I think white king can run away to b3 or capture b4, or did I misunderstand something? Or is it "double check"?
Answers.UserDisplayName: Andrew T.
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-06-22T19:23:56.133Z
Answers.Text: @AndrewT. it's double-check. I'd use `#` for mate.
Answers.UserDisplayName: Glorfindel
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-10-12T10:41:05.140Z
Answers.Text: This can't be the solution. The King must have walked illegally into that double check. "i" is Bishop, "K" is knight. "g" is rook.
Answers.UserDisplayName: LocalFluff
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-10-12T10:49:38.697Z
Answers.Text: @LocalFluff Black's last move was with a pawn on b2, capturing a White piece on c1 and promoting to Rook. `i` can't be a Bishop, because a White Bishop on a5 would put the Black King in check as well.
Answers.UserDisplayName: Glorfindel
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-06-22T12:45:14.290Z
Answers.LastActivityDate: 2017-06-22T12:45:14.290Z
Answers.UserDisplayName: Glorfindel
Body: <p>Here is a knight rebus. Each letter represents a different type of piece.
  Uppercase letters are one color and lowercase letters are the other.</p>
  <p>Determine the position. If possible, also determine the previous moves.</p>
  <p><a href="https://i.sstatic.net/6JVio.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/6JVio.png" alt="Rebus" /></a></p>
  <p><strong>n</strong> and <strong>N</strong> are kings and <strong>h</strong> is pawn. What is the rest?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-06-22T12:02:23.597Z
Comments.Text: Are you sure this is chess?
Comments.UserDisplayName: SmallChess
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-06-22T12:18:15.207Z
Comments.Text: I'd say it isn't. At least not with standard rules.
Comments.UserDisplayName: Annatar
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-06-27T14:24:33.510Z
Comments.Text: @Peter What is the source of this problem? Is there a significance to the choice of letters used to encode the pieces?
Comments.UserDisplayName: yrodro
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-06-28T05:26:34.777Z
Comments.Text: @yrodro The source is XX all-Ukrainian tournament among young mathematicians. "Knight" is just a word of six different letters.
Comments.UserDisplayName: Peter Mudrievskij
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-10-12T03:41:12.907Z
Comments.Text: What's I, which side of the board is white, and which types of pieces are white.
Comments.UserDisplayName: Tony Ennis
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2017-10-12T05:46:18.790Z
Comments.Text: @tony 1. Capital `I` represents the same piece as lowercase `i` but with different colour (namely, if `I` means "a black peace" then `i` means "a white peace" and vice versa). 2. As usual, white pieces move bottom up, black - top down. So the answer to your question is, I guess, bottom side of the board is white. 3. In the [answer](https://chess.stackexchange.com/questions/17894/knight-rebus-decipher-an-encoded-chess-position/17897#17897) below you can see that the pieces represented in capital letters are white.
Comments.UserDisplayName: Peter Mudrievskij
Tags: <problems><retrograde-analysis>
Title: "Knight rebus"-Decipher an encoded chess position
ThreadText: # "Knight rebus"-Decipher an encoded chess position
  
  (Asked by: username_0 on 2017-06-22)
  
  Here is a knight rebus. Each letter represents a different type of piece.
  Uppercase letters are one color and lowercase letters are the other.
  
  Determine the position. If possible, also determine the previous moves.
  
  [![Rebus](https://i.sstatic.net/6JVio.png)](https://i.sstatic.net/6JVio.png)
  
  **n** and **N** are kings and **h** is pawn. What is the rest?
  
  **Tags:** problems, retrograde-analysis
  
  > **Comments:**
  > **username_1**: Are you sure this is chess?  
  > **username_2**: I'd say it isn't. At least not with standard rules.  
  > **username_3**: @Peter What is the source of this problem? Is there a significance to the choice of letters used to encode the pieces?  
  > **username_0**: @username_3 The source is XX all-Ukrainian tournament among young mathematicians. "Knight" is just a word of six different letters.  
  > **username_4**: What's I, which side of the board is white, and which types of pieces are white.  
  > **username_0**: @tony 1. Capital `I` represents the same piece as lowercase `i` but with different colour (namely, if `I` means "a black peace" then `i` means "a white peace" and vice versa). 2. As usual, white pieces move bottom up, black - top down. So the answer to your question is, I guess, bottom side of the board is white. 3. In the [answer](https://chess.stackexchange.com/questions/17894/knight-rebus-decipher-an-encoded-chess-position/17897#17897) below you can see that the pieces represented in capital letters are white.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_8 on 2017-06-22. Score: 12 | Accepted answer
  
  Assume the board is in it's usual position (the bottom row is the first row) then this is the solution:
  [FEN "1B6/8/1k6/R7/1n6/2K5/r6p/q1r1n3 - - - 0 1"]
  
  and Black's last move was b2xc1R++.
  I could write an explanation here about I came to this result, but it would essentially be copying @Maxwell's answer. I didn't use it, though.
  
  > **Comments:**
  > **username_2**: Heh, I even thought about the possibility of multiple queens by promotion, but this is quite an interesting twist. Well done.  
  > **username_9**: I assume `++` is a checkmate symbol, but is it really a checkmate? I think white king can run away to b3 or capture b4, or did I misunderstand something? Or is it "double check"?  
  > **username_8**: @AndrewT. it's double-check. I'd use `#` for mate.  
  > **username_7**: This can't be the solution. The King must have walked illegally into that double check. "i" is Bishop, "K" is knight. "g" is rook.  
  > **username_8**: @username_7 Black's last move was with a pawn on b2, capturing a White piece on c1 and promoting to Rook. `i` can't be a Bishop, because a White Bishop on a5 would put the Black King in check as well.  
  
  ---
  
  ### Answer by username_5 on 2017-06-22. Score: 7
  
  Yes indeed, n corresponds to king, as we need two kings of a different color to have a legal chess position.
  
  Also, as you give, h = pawn, as otherwise we would have a pawn on the first or last rank, which would be illegal.
  
  Consider i.
  It cannot be a queen, as both kings would be in check.
  It cannot be a knight, as the "i" on a2 would give check. There is no legal way where "knight a2 check" is the last move.
  It cannot be a bishop, as the "I" on a5 would give check. There is no legal way where "bishop a5 check" is the last move.
  Therefore, i = rook.
  
  We see that the king on c3 is in check by the rook on c1. Therefore, g cannot be a queen or a bishop, because there is no legal way to obtain the resulting position.
  So, g = knight.
  
  The "K" on b8 should not give check to the king on b6.
  Therefore, k = bishop and t = queen.
  
  [However, the resulting position seems to be impossible to achieve too...
  As far as I can see, the puzzle has no solution.]
  
  **Edit: the resulting position is indeed possible**, see the answer of username_8.
  
  > **Comments:**
  > **username_5**: You're welcome and thank you for the question.  
  
  ---
  
  ### Answer by username_6 on 2017-10-12. Score: 2
  
  This is a basic example of an orthodox retro form which has been taken to a new level over the last year by Ukrainian composer Andrey Frolkin and Canadian Jeff Coakley. I recently acquired a lovely landscape painting by Andrey's wife, Nina, which contains an embedded rebus by Andrey, who I bet authored the problem OP posted!
  Although Maxwell's excellent proof relied at a couple of place on the edge of the board preventing retro-movement, this is not actually necessary. Shift all the pieces one square to the right (except for h on h2), and the problem remains sound (and in my opinion slightly superior :D )!
  Proof: first count the pieces.
  
        K N I G H T
  Upper 1 1 1 0 0 0
  Lower 0 1 2 2 1 1
  
  So N is king and by examining first and last ranks, H is pawn. Observe that whatever I represents, one instance is giving check to the enemy king. So any other checking unit implies a double check. So G is not a diagonal unit (bishop or queen), and K is not an orthogonal unit (rook or queen), since the resulting double checks are impossible. And I is not queen, or both kings would be in check!
  So by elimination the queen is represented by T and we do have double check. So I can only be rook, and the position is achieved through promotion. Hence lower case is Black. G must be knight so by elimination K is bishop.  
  [title "Frolkin? version username_6 rebus: solution"]
  [fen "2B5/8/2k5/1R6/2n5/3K4/1r5p/1q1r1n2 w - - 0 1"]
  
  and Black's last move was c2xd1=R++
  
  > **Comments:**
  > **username_7**: So, what was the last move? That the white King walked illegally into that double check? "i" is Bishop, "K" is knight. "g" is rook  
  > **username_6**: @username_7: Thanks for the question. Last move was black pawn on c2 capturing something on d1 and promoting to rook check, also discovering check from queen. The solution would **have** to be something like this to allow white and black to be distinguished. If I,K&G are as you suggested, then both kings are in check: wKd3 from bQb1 and bKc6 from wBb5.  
  
  ---
  
  