Answers.Body: <blockquote>
    <p>Would either of them be more likely to occur than under promotion to a bishop? or a rook? or a knight?</p>
  </blockquote>
  
  <p>I'm sure your scenarios wouldn't happen more often than promotion to a knight. Knight promotion is not impossible in competitive chess, whereas your scenarios most likely occur in chess composition.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-04-30T23:49:21.417Z
Answers.LastActivityDate: 2018-04-30T23:49:21.417Z
Answers.UserDisplayName: SmallChess
Answers.Body: <p>I have found examples of the open cases from Laska's answer, with the first one being an old composition and the second one a modern one. To answer the question directly, the occurrence percentages of these cases happening are also 0%.</p>
  <p>Case #1</p>
  <pre><code>[Title &quot;Gyula Breyer, Magyar Sakkvilag, 1918, White To Play And Win&quot;]
  [FEN &quot;1N1bknbr/2p1Pn1p/2K1Rp1p/4pP1B/p3p3/p3P1N1/P6P/8 w - - 0 1&quot;]
  </code></pre>
  <p>Addendum 4/20/2020: This problem is actually cooked and promoting to a black queen, as Breyer originally intended, doesn’t work. See the analysis <a href="https://chess.stackexchange.com/questions/29633/gyula-breyer-joke-composition-cooked/29635#29635">here.</a></p>
  <p>This brilliant composition can be found on the <a href="http://superproblem.ru/archive/raznoe/S_umor-1.html" rel="nofollow noreferrer">SuperProbblem website,</a>, a Google Books preview of <a href="https://books.google.com/books?id=XCkJzeG4D-oC&amp;pg=PA84&amp;lpg=PA84&amp;dq=gyula+breyer+1918&amp;source=bl&amp;ots=EgkxEk-VM8&amp;sig=ACfU3U2H3RKf4oXvLFODmAcDnWPY4Bm3uQ&amp;hl=en&amp;sa=X&amp;ved=2ahUKEwiFjaeUhfXlAhVLIqwKHTR8CzAQ6AEwBXoECAgQAQ#v=onepage&amp;q=gyula%20breyer%201918&amp;f=false" rel="nofollow noreferrer">Outrageous Chess Problems</a>, and in the <a href="https://pdb.dieschwalbe.de/P1372243" rel="nofollow noreferrer">Die Schwalbe Databse</a>.</p>
  <p>Case #2</p>
  <pre><code>[Title &quot;James Malcom, PDB Website 2020, Mate In 2&quot;]
  [FEN &quot;1k1K3r/3Q2P1/1N6/8/8/8/8/8 w - - 0 1&quot;]
  </code></pre>
  <p>Moving the White or blocking the rook's check does not mate in time, nor does any promotion to a White piece, since it is then stalemate. Promotion to a Black piece doesn't mate in time either, so someting must be done. The solution is for White must promote to a Black pawn! This avoids stalemate and Black has no interference with 2. Qc7#. This problem comes from the <a href="https://pdb.dieschwalbe.de/P1375482" rel="nofollow noreferrer">Die Schwalbe Database</a>.</p>
  <p>I also found a fun retrograde analysis <a href="https://pdb.dieschwalbe.de/P1380851" rel="nofollow noreferrer">problem</a> that relates to Case #2.</p>
  <p>Addendum 10/30/2020-While browsing on PDB, I find an improved version of what was previously here, so it has been shown in place along with a revised solution, of course.</p>
  <pre><code>[Title &quot;Andrew Buchanan &amp; James Malcom, PDB Website 12/10/2020, Mate In 2 Moves&quot;]
  [FEN &quot;8/1N1B4/kPpK4/PN6/8/8/8/8 w - - 0 1&quot;]
  </code></pre>
  <p>Solution: 1. bxc7 en passant! Kxb7 2. c8=Q.</p>
  <p><strong>Explanation</strong></p>
  <p>What was Black's last move? The b5 pawn couldn't have come from anywhere, and the Black king has no prior move being in an illegal double check. Nor could come from a square that a White piece is occupying. Therefore Black's last move must have been c8-c6! This is possible because White formerly promoted into a Black pawn! Black then must have done a double-step for their last move, so therefore the en passant capture is a valid solution!</p>
  <p>The 2018 FIDE laws state: &quot;3.7.2 on its first move the pawn may move as in 3.7.1 or alternatively it may advance two squares along the same file, provided that both squares are unoccupied.&quot; Hence, Black's newborn 8th rank pawn, which has never been moved before, reserves the right to commence a double-step on its first move, and likewise White receives the right to capture it en passant as they do with a 7th rank pawn.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-11-19T02:24:59.930Z
Answers.LastActivityDate: 2020-11-18T05:22:25.597Z
Answers.LastEditDate: 2020-11-18T05:22:25.597Z
Answers.UserDisplayName: Rewan Demontay
Answers.Body: <p>Thanks for your great question. Here's what I think about the relative frequency of different joke promotions, in games and compositions. Many such compositions are helpmates or selfmates, but the rationale for promotion choice is already a bit peculiar in those, so in this topic we'll focus on games, direct mates or studies.</p>
  <p><strong>Regular promotions</strong></p>
  <p>First, a quick review of the frequency of legal promotions, as quoted in the Wikipedia page you pointed at:</p>
  <blockquote>
  <p><strong>Piece      %</strong><br />
  Queen  96.9<br />
  Knight  1.8<br />
  Rook    1.1<br />
  Bishop  0.2</p>
  </blockquote>
  <p>Couple of points:</p>
  <p>(1) A knight promotion is arguably not an under-promotion, in that the promoted piece gets immediate access to squares that the queen does not. The most common use of a knight promotion is in hot positions where a tempo is key.</p>
  <p>(2) Rook and bishop are definite under-promotions: they may be used to turn a draw into a win by avoiding stalemating the opponent. But they might also be used (more in compositions than in real life) to turn a loss into a draw by entering a block position.</p>
  <p>(3) I doubt that the need for a bishop promotion is as high as 0.2%. There are certainly cases where it is the answer, but I suspect that these are dwarfed by those where B under-promotion was selected for fun. I have certainly seen GM Hikaru Nakamura do this for grins against computers.</p>
  <p><strong>The Dummy Pawn</strong></p>
  <p>The dummy pawn takes the idea of under-promotion to its logical extreme. In principle, it would mainly be used in games to turn a lost position into a draw, since (unlike bishop or rook) it doesn't rely on other pieces to be blocked. But positions have also been constructed where the dummy pawn can turn a draw into a win. Here, the defensive player would have two alternative lines, one drawing against a bishop, the other to draw against a rook. For all the drama, I don't know of any tournament where the dummy pawn rule of 1862 was actually played. There are some good compositions though, but returning to the frequency comparison, dummy pawn would come in at approximately 0.0%!</p>
  <p><strong>Enemy unit</strong></p>
  <p>Moving on to promotions to enemy unit. There are numerous 19th century joke promotion problems relying on promotion to enemy officer. According to chess historian Mario Richter, one influence here was Bilguer's <em>Handbuch des Schachspiels</em>, which was for many generations of chess players <em>the</em> reference work on chess. Especially it refers to the paragraph defining the rule of promotion:</p>
  <blockquote>
  <p>Gelangt [der Bauer] auf die letzte Reihe des Brettes, auf welcher anfangs die Offiziere des Gegners stehen, so muß der Besitzer ihn augenblicklich umwandeln und zu einem beliebigen Offizier machen. Hierbei kann man eine zweite Dame, einen dritten Springer u.s.w. wählen; nur versteht es sich, daß der Bauer nicht in einen zweiten König verwandelt werden darf.</p>
  <p>(If the pawn reaches the last rank, which is occupied in the starting position by the enemy officers, it has to be immediately promoted to an arbitrary officer. In this way you can have a second queen, a third knight etc, but you cannot have a second king.)</p>
  </blockquote>
  <p>So Bilguer forgot to specify that the promoted officer should have the same colour as the pawn!</p>
  <p>There are many joke compositions involving promotion to enemy knight, bishop or rook. If one was looking for their movement capabilities, then these might be replaced by a  friendly dummy pawn instead, which cannot move at all. However, an enemy unit is that it cannot be captured by another enemy unit, in particular it blocks a flight square for the king. It can also serve to prevent stalemating the opponent, by giving him a new piece to move around.</p>
  <p>It is normally assumed that promotion to enemy rook can be followed by castling.</p>
  <p>So in summary, I think the enemy officer is less useful than friendly dummy pawn for getting one's self stalemated, and more useful for avoiding stalemating the opponent. The relative frequencies would reflect this, approx 0.0% again.</p>
  <p><strong>Open Cases</strong></p>
  <p>There are two open cases where I know of no existing compositions:<br />
  (1) Promotion to enemy queen. How could it be in my interest to promote a pawn to enemy queen rather than enemy rook or bishop?<br />
  (2) Promotion to enemy pawn. This would require a new rule: how does a pawn on first row move? And by analogy with the rook, can it double-step?</p>
  <p>(Promotions to king, white or black are also found in problems, but let's follow Bilguer to exclude them from scope because the field of discussion here is already broad enough, and they would require an extension to the rules concerning how checkmate works against multiple kings.)</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-05-06T00:14:58.980Z
Answers.Text: Thanks for the answer.  I hadn't considered promotion to an enemy piece or a dummy pawn to avoid stalemate, but it makes sense.  As far as the question of the enemy pawn's first move, that would depend on the wording of the rules, I'd assume. Do they say it can double step on its first move, or its move from the second rank? Both FIDE and USCF say "first move."
Answers.UserDisplayName: anotherguy
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-05-06T01:45:22.903Z
Answers.Text: Yes I’d say the pawn can make a double step on its first move. If a pawn promotes to an enemy rook, then normally it is allowed to castle: I.e. it’s considered to be a new piece which has never moved.
Answers.UserDisplayName: Laska
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-09T21:49:57.267Z
Answers.Text: You could stalemate yourself by promoting an enemy queen.
Answers.UserDisplayName: Ángel
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-10-10T09:13:49.373Z
Answers.Text: Knights can also be promoted to prevent a fork in certain endgames
Answers.UserDisplayName: David
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-05-03T06:59:44.523Z
Answers.LastActivityDate: 2020-10-10T04:10:38.317Z
Answers.LastEditDate: 2020-10-10T04:10:38.317Z
Answers.UserDisplayName: Laska
Body: <p>Underpromotion is an interesting aspect of chess, but there are other possibilities that aren't allowed under modern rules.</p>
  
  <p>One is the so called "<a href="https://en.wikipedia.org/wiki/Promotion_(chess)#1862_British_Chess_Association_rule" rel="nofollow noreferrer">dummy pawn</a>" as this question discusses:
  <a href="https://chess.stackexchange.com/questions/21212/when-if-ever-was-it-a-rule-that-pawn-promotion-was-optional">When (if ever) was it a rule that pawn promotion was optional?</a> where the goal would be to stalemate oneself.  </p>
  
  <p>Another is promoting the pawn to a piece of the opposite color, where the goal could be to smother the enemy king with one of his "own" pieces, as in the Wikipedia example, or perhaps to cause one's own king to be stalemated with the help of the newly created enemy piece.</p>
  
  <p>If both of these were allowed, promoting to a weak enemy piece would often serve the same purpose as a dummy pawn, so in such cases, suppose the dummy pawn is our default, if it works.</p>
  
  <p>Which of these situations would be less likely to occur? Would either of them be more likely to occur than underpromotion to a rook, bishop, or a knight?</p>
  
Tags: <endgame><chess-variants><pawn-promotion>
Title: How likely is it that a non-orthodox promotion is optimal?
ThreadText: # How likely is it that a non-orthodox promotion is optimal?
  
  (Asked by: username_0 on 2018-04-30)
  
  Underpromotion is an interesting aspect of chess, but there are other possibilities that aren't allowed under modern rules.
  
  One is the so called "[dummy pawn](https://en.wikipedia.org/wiki/Promotion_(chess)#1862_British_Chess_Association_rule)" as this question discusses:
  [When (if ever) was it a rule that pawn promotion was optional?](https://chess.stackexchange.com/questions/21212/when-if-ever-was-it-a-rule-that-pawn-promotion-was-optional) where the goal would be to stalemate oneself.
  
  Another is promoting the pawn to a piece of the opposite color, where the goal could be to smother the enemy king with one of his "own" pieces, as in the Wikipedia example, or perhaps to cause one's own king to be stalemated with the help of the newly created enemy piece.
  
  If both of these were allowed, promoting to a weak enemy piece would often serve the same purpose as a dummy pawn, so in such cases, suppose the dummy pawn is our default, if it works.
  
  Which of these situations would be less likely to occur? Would either of them be more likely to occur than underpromotion to a rook, bishop, or a knight?
  
  **Tags:** endgame, chess-variants, pawn-promotion
  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_3 on 2018-05-03. Score: 9 | Accepted answer
  
  Thanks for your great question. Here's what I think about the relative frequency of different joke promotions, in games and compositions. Many such compositions are helpmates or selfmates, but the rationale for promotion choice is already a bit peculiar in those, so in this topic we'll focus on games, direct mates or studies.
  
  **Regular promotions**
  
  First, a quick review of the frequency of legal promotions, as quoted in the Wikipedia page you pointed at:
  
  > **Piece %**  
  > Queen 96.9  
  > Knight 1.8  
  > Rook 1.1  
  > Bishop 0.2
  
  Couple of points:
  
  (1) A knight promotion is arguably not an under-promotion, in that the promoted piece gets immediate access to squares that the queen does not. The most common use of a knight promotion is in hot positions where a tempo is key.
  
  (2) Rook and bishop are definite under-promotions: they may be used to turn a draw into a win by avoiding stalemating the opponent. But they might also be used (more in compositions than in real life) to turn a loss into a draw by entering a block position.
  
  (3) I doubt that the need for a bishop promotion is as high as 0.2%. There are certainly cases where it is the answer, but I suspect that these are dwarfed by those where B under-promotion was selected for fun. I have certainly seen GM Hikaru Nakamura do this for grins against computers.
  
  **The Dummy Pawn**
  
  The dummy pawn takes the idea of under-promotion to its logical extreme. In principle, it would mainly be used in games to turn a lost position into a draw, since (unlike bishop or rook) it doesn't rely on other pieces to be blocked. But positions have also been constructed where the dummy pawn can turn a draw into a win. Here, the defensive player would have two alternative lines, one drawing against a bishop, the other to draw against a rook. For all the drama, I don't know of any tournament where the dummy pawn rule of 1862 was actually played. There are some good compositions though, but returning to the frequency comparison, dummy pawn would come in at approximately 0.0%!
  
  **Enemy unit**
  
  Moving on to promotions to enemy unit. There are numerous 19th century joke promotion problems relying on promotion to enemy officer. According to chess historian Mario Richter, one influence here was Bilguer's *Handbuch des Schachspiels*, which was for many generations of chess players *the* reference work on chess. Especially it refers to the paragraph defining the rule of promotion:
  
  > Gelangt [der Bauer] auf die letzte Reihe des Brettes, auf welcher anfangs die Offiziere des Gegners stehen, so muß der Besitzer ihn augenblicklich umwandeln und zu einem beliebigen Offizier machen. Hierbei kann man eine zweite Dame, einen dritten Springer u.s.w. wählen; nur versteht es sich, daß der Bauer nicht in einen zweiten König verwandelt werden darf.
  >
  > (If the pawn reaches the last rank, which is occupied in the starting position by the enemy officers, it has to be immediately promoted to an arbitrary officer. In this way you can have a second queen, a third knight etc, but you cannot have a second king.)
  
  So Bilguer forgot to specify that the promoted officer should have the same colour as the pawn!
  
  There are many joke compositions involving promotion to enemy knight, bishop or rook. If one was looking for their movement capabilities, then these might be replaced by a friendly dummy pawn instead, which cannot move at all. However, an enemy unit is that it cannot be captured by another enemy unit, in particular it blocks a flight square for the king. It can also serve to prevent stalemating the opponent, by giving him a new piece to move around.
  
  It is normally assumed that promotion to enemy rook can be followed by castling.
  
  So in summary, I think the enemy officer is less useful than friendly dummy pawn for getting one's self stalemated, and more useful for avoiding stalemating the opponent. The relative frequencies would reflect this, approx 0.0% again.
  
  **Open Cases**
  
  There are two open cases where I know of no existing compositions:  
  (1) Promotion to enemy queen. How could it be in my interest to promote a pawn to enemy queen rather than enemy rook or bishop?  
  (2) Promotion to enemy pawn. This would require a new rule: how does a pawn on first row move? And by analogy with the rook, can it double-step?
  
  (Promotions to king, white or black are also found in problems, but let's follow Bilguer to exclude them from scope because the field of discussion here is already broad enough, and they would require an extension to the rules concerning how checkmate works against multiple kings.)
  
  > **Comments:**
  > **username_0**: Thanks for the answer.  I hadn't considered promotion to an enemy piece or a dummy pawn to avoid stalemate, but it makes sense.  As far as the question of the enemy pawn's first move, that would depend on the wording of the rules, I'd assume. Do they say it can double step on its first move, or its move from the second rank? Both FIDE and USCF say "first move."  
  > **username_3**: Yes I’d say the pawn can make a double step on its first move. If a pawn promotes to an enemy rook, then normally it is allowed to castle: I.e. it’s considered to be a new piece which has never moved.  
  > **username_4**: You could stalemate yourself by promoting an enemy queen.  
  > **username_5**: Knights can also be promoted to prevent a fork in certain endgames  
  
  ---
  
  ### Answer by username_1 on 2018-04-30. Score: 2
  
  > Would either of them be more likely to occur than under promotion to a bishop? or a rook? or a knight?
  
  I'm sure your scenarios wouldn't happen more often than promotion to a knight. Knight promotion is not impossible in competitive chess, whereas your scenarios most likely occur in chess composition.
  
  
  ---
  
  ### Answer by username_2 on 2019-11-19. Score: 2
  
  I have found examples of the open cases from username_3's answer, with the first one being an old composition and the second one a modern one. To answer the question directly, the occurrence percentages of these cases happening are also 0%.
  
  Case #1
  
  ```
  [Title "Gyula Breyer, Magyar Sakkvilag, 1918, White To Play And Win"]
  [FEN "1N1bknbr/2p1Pn1p/2K1Rp1p/4pP1B/p3p3/p3P1N1/P6P/8 w - - 0 1"]
  
  ```
  
  Addendum 4/20/2020: This problem is actually cooked and promoting to a black queen, as Breyer originally intended, doesn’t work. See the analysis [here.](https://chess.stackexchange.com/questions/29633/gyula-breyer-joke-composition-cooked/29635#29635)
  
  This brilliant composition can be found on the [SuperProbblem website,](http://superproblem.ru/archive/raznoe/S_umor-1.html), a Google Books preview of [Outrageous Chess Problems](https://books.google.com/books?id=XCkJzeG4D-oC&pg=PA84&lpg=PA84&dq=gyula+breyer+1918&source=bl&ots=EgkxEk-VM8&sig=ACfU3U2H3RKf4oXvLFODmAcDnWPY4Bm3uQ&hl=en&sa=X&ved=2ahUKEwiFjaeUhfXlAhVLIqwKHTR8CzAQ6AEwBXoECAgQAQ#v=onepage&q=gyula%20breyer%201918&f=false), and in the [Die Schwalbe Databse](https://pdb.dieschwalbe.de/P1372243).
  
  Case #2
  
  ```
  [Title "James Malcom, PDB Website 2020, Mate In 2"]
  [FEN "1k1K3r/3Q2P1/1N6/8/8/8/8/8 w - - 0 1"]
  
  ```
  
  Moving the White or blocking the rook's check does not mate in time, nor does any promotion to a White piece, since it is then stalemate. Promotion to a Black piece doesn't mate in time either, so someting must be done. The solution is for White must promote to a Black pawn! This avoids stalemate and Black has no interference with 2. Qc7#. This problem comes from the [Die Schwalbe Database](https://pdb.dieschwalbe.de/P1375482).
  
  I also found a fun retrograde analysis [problem](https://pdb.dieschwalbe.de/P1380851) that relates to Case #2.
  
  Addendum 10/30/2020-While browsing on PDB, I find an improved version of what was previously here, so it has been shown in place along with a revised solution, of course.
  
  ```
  [Title "Andrew Buchanan & James Malcom, PDB Website 12/10/2020, Mate In 2 Moves"]
  [FEN "8/1N1B4/kPpK4/PN6/8/8/8/8 w - - 0 1"]
  
  ```
  
  Solution: 1. bxc7 en passant! Kxb7 2. c8=Q.
  
  **Explanation**
  
  What was Black's last move? The b5 pawn couldn't have come from anywhere, and the Black king has no prior move being in an illegal double check. Nor could come from a square that a White piece is occupying. Therefore Black's last move must have been c8-c6! This is possible because White formerly promoted into a Black pawn! Black then must have done a double-step for their last move, so therefore the en passant capture is a valid solution!
  
  The 2018 FIDE laws state: "3.7.2 on its first move the pawn may move as in 3.7.1 or alternatively it may advance two squares along the same file, provided that both squares are unoccupied." Hence, Black's newborn 8th rank pawn, which has never been moved before, reserves the right to commence a double-step on its first move, and likewise White receives the right to capture it en passant as they do with a 7th rank pawn.
  
  
  ---
  
  