Answers.Body: <p>Using the <a href="https://syzygy-tables.info/" rel="nofollow noreferrer">syzygy tablebases</a> by just putting some B+N position in, and looking for the note that says what the longest one is, we can find that it's</p>
  <pre><code>8/8/8/6B1/8/8/4k3/1K5N b - - 0 1
  </code></pre>
  <p>with a DTM (depth to mate, in plies/half moves) of 65.</p>
  <p>This is probably due to the discoordination of all of white's pieces</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-02-27T07:08:49.293Z
Answers.Text: That's great worth a +1 thanks. Speaking of +1, it's Black to move, and the 66th single move (by White) is the checkmate
Answers.UserDisplayName: Laska
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Answers.CreationDate: 2021-02-27T08:03:12.053Z
Answers.Text: Not very surprising, also the position with Kh8 instead of Kg8 works. So does Kf8, BTW.
Answers.UserDisplayName: Hauke Reddmann
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Answers.CreationDate: 2021-03-02T04:59:21.170Z
Answers.Text: Taking Hauke’s labelling of the squares, if you shift B from b4 to a3 then Black can draw!
Answers.UserDisplayName: Laska
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Answers.CreationDate: 2021-02-27T04:09:51.147Z
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Answers.UserDisplayName: pulsar512b
Body: <p>Black is trying to avoid a mating net that forces it into the wrong corner. To build the mating net, the White king should cut the black king off the center first, by controlling the center itself. Black can resist that without getting into a form of a mating net. I thought it might be this position where black has no danger of a mating net and has cut the white king off the center.</p>
  <pre><code>[FEN &quot;6BK/5N2/5k2/8/8/8/8/8 w - - 0 1&quot;]
  </code></pre>
  <p>I want to capture the essence of this checkmate without relying on brute force search. Just defining general goals that can be extracted from any position.</p>
  <p>I am not asking the technique of mating, just how to express them clearly in a systematic way to a computer.</p>
  
Tags: <checkmate><patterns>
Title: What is the B+N checkmate position that leads to a longest mate?
ThreadText: # What is the B+N checkmate position that leads to a longest mate?
  
  (Asked by: username_0 on 2021-02-26)
  
  Black is trying to avoid a mating net that forces it into the wrong corner. To build the mating net, the White king should cut the black king off the center first, by controlling the center itself. Black can resist that without getting into a form of a mating net. I thought it might be this position where black has no danger of a mating net and has cut the white king off the center.
  [FEN "6BK/5N2/5k2/8/8/8/8/8 w - - 0 1"]
  
  I want to capture the essence of this checkmate without relying on brute force search. Just defining general goals that can be extracted from any position.
  I am not asking the technique of mating, just how to express them clearly in a systematic way to a computer.
  
  **Tags:** checkmate, patterns
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2021-02-27. Score: 3 | Accepted answer
  
  Using the syzygy tablebases by just putting some B+N position in, and looking for the note that says what the longest one is, we can find that it's
  8/8/8/6B1/8/8/4k3/1K5N b - - 0 1
  
  with a DTM (depth to mate, in plies/half moves) of 65.
  This is probably due to the discoordination of all of white's pieces
  
  > **Comments:**
  > **username_2**: That's great worth a +1 thanks. Speaking of +1, it's Black to move, and the 66th single move (by White) is the checkmate  
  > **username_3**: Not very surprising, also the position with Kh8 instead of Kg8 works. So does Kf8, BTW.  
  > **username_2**: Taking Hauke’s labelling of the squares, if you shift B from b4 to a3 then Black can draw!  
  
  ---
  
  