Answers.Body: <p>It's easy to get 16/17 = 94.1%</p>
  <pre><code>[FEN &quot;4B3/4Q3/3QQQ2/1N2B2N/4k3/1Q5Q/3PKP2/2R1Q1R1 w - - 0 1&quot;]
  </code></pre>
  <p>On further thought that's not legal for lack of a previous Black move.
  This should be fixable, but meanwhile I see that 19/20 = 95% is possible:</p>
  <pre><code>[FEN &quot;8/3Q1Q2/3Q2R1/1Q3N2/n3kBQ1/1B6/n2RKP2/1n2QQQN w - - 0 1&quot;]
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-24T08:55:03.540Z
Answers.Text: I had thought Hauke's edit meant no batteries are allowed as that means neither piece can be counted as quite making the mate? Far as I read it, though, batteries are still allowed and the definition still reads the same.
Answers.UserDisplayName: Rewan Demontay
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-24T09:25:11.587Z
Answers.Text: Batteries *are* allowed but note that in Noams first example, Qe1 can't mate *by moving* (which is easily fixed). Second one might be the theoretical maximum (the idea with the bN is utterly brill).
Answers.UserDisplayName: Hauke Reddmann
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-23T22:33:49.300Z
Answers.LastActivityDate: 2023-12-23T23:00:25.000Z
Answers.LastEditDate: 2023-12-23T23:00:25.000Z
Answers.UserDisplayName: Noam D. Elkies
Answers.Body: <p>26/28, 92.86%, maximum.</p>
  <pre><code>[FEN &quot;5k2/Q1Q1RBNQ/1N1B1Q1Q/1QN2Q2/1qn2q2/1n1b1q1q/q1q1rbnq/5K2 w - - 0 1&quot;]
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-23T09:51:52.583Z
Answers.Text: I see I shot myself in the foot. On the last SCHWALBE meeting a member introduced his book "Who mates?", and here it applies to the bishops. You can argue that the Bf7 mates (it moves) and that the Bd6 mates (it checks), but not both! I will edit the question accordingly.
Answers.UserDisplayName: Hauke Reddmann
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-01-23T02:42:06.453Z
Answers.Text: Whose book is who mates? Can you give some details please
Answers.UserDisplayName: Laska
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-01-23T04:39:20.433Z
Answers.Text: @Laska Both sides mate, all is symmetrical.
Answers.UserDisplayName: Rewan Demontay
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2024-01-25T10:20:52.733Z
Answers.Text: We can argue whether the Bd6 mates even if we allow mate without moving: it is only checking in a check mate after 1.Re8# but this particular check is not necessary for the mate (remove Bd6 and it's still mate ; the Re8 is doing the important check). 1.Re5?, OTOH, is not mate because of 1...Nxd6.
Answers.UserDisplayName: Evargalo
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-12-22T08:54:52.593Z
Answers.LastActivityDate: 2023-12-22T09:21:44.940Z
Answers.LastEditDate: 2023-12-22T09:21:44.940Z
Answers.UserDisplayName: Rewan Demontay
Body: <p>In the newest SCHWALBE, positions are given where <em>any</em> piece on the board can give a check (any being surprisingly high). A quick dabbling seems to prove that it is <em>not</em> possible that any piece can mate. (Only try is something like Kf3 Qg2 - Kd5 Qc6, but how to take the flights?)</p>
  <p>Thus the next best would be &quot;Find a position where a maximal fraction of pieces can mate&quot;. (Of course we suppose either side may have the move.) What is your record attempt?</p>
  <p>EDIT! &quot;Can mate&quot; is unprecise since in the case of a battery it is a priori unclear who mates (you can argue for both positions). I usually go for &quot;only a piece that checks can mate&quot;, but in this special case (as you can already infer from the first paragraph) I prefer the other interpretation and formulate more precise &quot;Find a position where a maximal fraction of pieces can make a move (or more) that delivers mate&quot;.</p>
  <pre><code>[FEN &quot;8/8/8/8/1Q6/K7/7q/k7 w KQkq - 0 1&quot;]
  </code></pre>
  <p>Example: 50% of all pieces can mate</p>
  
Tags: <problems><puzzles><records>
Title: Max percentage of mating pieces
ThreadText: # Max percentage of mating pieces
  
  (Asked by: username_0 on 2023-12-22)
  
  In the newest SCHWALBE, positions are given where *any* piece on the board can give a check (any being surprisingly high). A quick dabbling seems to prove that it is *not* possible that any piece can mate. (Only try is something like Kf3 Qg2 - Kd5 Qc6, but how to take the flights?)
  
  Thus the next best would be "Find a position where a maximal fraction of pieces can mate". (Of course we suppose either side may have the move.) What is your record attempt?
  
  EDIT! "Can mate" is unprecise since in the case of a battery it is a priori unclear who mates (you can argue for both positions). I usually go for "only a piece that checks can mate", but in this special case (as you can already infer from the first paragraph) I prefer the other interpretation and formulate more precise "Find a position where a maximal fraction of pieces can make a move (or more) that delivers mate".
  
  ```
  [FEN "8/8/8/8/1Q6/K7/7q/k7 w KQkq - 0 1"]
  
  ```
  
  Example: 50% of all pieces can mate
  
  **Tags:** problems, puzzles, records
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_1 on 2023-12-23. Score: 3
  
  It's easy to get 16/17 = 94.1%
  
  ```
  [FEN "4B3/4Q3/3QQQ2/1N2B2N/4k3/1Q5Q/3PKP2/2R1Q1R1 w - - 0 1"]
  
  ```
  
  On further thought that's not legal for lack of a previous Black move.
  This should be fixable, but meanwhile I see that 19/20 = 95% is possible:
  
  ```
  [FEN "8/3Q1Q2/3Q2R1/1Q3N2/n3kBQ1/1B6/n2RKP2/1n2QQQN w - - 0 1"]
  
  ```
  
  > **Comments:**
  > **username_2**: I had thought username_0's edit meant no batteries are allowed as that means neither piece can be counted as quite making the mate? Far as I read it, though, batteries are still allowed and the definition still reads the same.  
  > **username_0**: Batteries *are* allowed but note that in Noams first example, Qe1 can't mate *by moving* (which is easily fixed). Second one might be the theoretical maximum (the idea with the bN is utterly brill).  
  
  ---
  
  ### Answer by username_2 on 2023-12-22. Score: 0
  
  26/28, 92.86%, maximum.
  
  ```
  [FEN "5k2/Q1Q1RBNQ/1N1B1Q1Q/1QN2Q2/1qn2q2/1n1b1q1q/q1q1rbnq/5K2 w - - 0 1"]
  
  ```
  
  > **Comments:**
  > **username_0**: I see I shot myself in the foot. On the last SCHWALBE meeting a member introduced his book "Who mates?", and here it applies to the bishops. You can argue that the Bf7 mates (it moves) and that the Bd6 mates (it checks), but not both! I will edit the question accordingly.  
  > **username_3**: Whose book is who mates? Can you give some details please  
  > **username_2**: @username_3 Both sides mate, all is symmetrical.  
  > **username_4**: We can argue whether the Bd6 mates even if we allow mate without moving: it is only checking in a check mate after 1.Re8# but this particular check is not necessary for the mate (remove Bd6 and it's still mate ; the Re8 is doing the important check). 1.Re5?, OTOH, is not mate because of 1...Nxd6.  
  
  ---
  
  