Answers.Body: <p>It takes at most 33 moves to win this endgame from any position (excluding positions where bishop or knight can be captured). See <a href="https://en.wikipedia.org/wiki/Bishop_and_knight_checkmate" rel="noreferrer">https://en.wikipedia.org/wiki/Bishop_and_knight_checkmate</a> and references there.</p>
  
  <p>So, no, a forced draw is not possible in this endgame. However if the defending side is playing perfectly (e.g. an engine with tablebase), it could be very hard to win this for a human within 50 moves if you start from one of those 33-moves-to-mate positions. </p>
  
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Answers.CreationDate: 2018-01-24T06:41:24.867Z
Answers.Text: I would not say that it;s hard in terms of technique, but humans get tired, and a single slip can cost you 5 or 6 moves.
Answers.UserDisplayName: DanielWainfleet
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Answers.CreationDate: 2018-01-25T19:56:54.550Z
Answers.Text: @DanielWainfleet That's exactly what I wrote: *hard to win ... within 50 moves*.  As for technique, indeed, it is pretty easy once you know how the knight is supposed to move...
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Answers.CreationDate: 2018-01-27T02:39:26.737Z
Answers.Text: Many years ago Scientific America had a brief note about the old Q of whether in general  R+B could win against 2 Knights, with no pawns or other pieces left (except of course the Kings). Regressive analysis by computer (basically analyzing backwards from winning positions) said YES, but only if the 50-move rule is waived. The longest variation took 233 moves to a forced win of one of the Knights, followed by about 20 more moves to mate
Answers.UserDisplayName: DanielWainfleet
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Answers.CreationDate: 2018-01-28T03:29:20.463Z
Answers.Text: The following ending even requires 545 moves to be won by white : W: Kd3 Qh1 Nh2  vs B: Kf4 Ra7 Bd1 Nh7 with black to play.
Answers.UserDisplayName: Emphyrio
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Answers.CreationDate: 2018-01-28T03:38:36.907Z
Answers.Text: Important to know as well : in chess endgame studies, the 50move rule doesn't apply (unless expressedly specified, but it 's rarely the case). Many engame studies have some secondary lines whose validity depends of some tablebase result giving a win longer than 50 DTZ. That s why usually composers don't use syzygy tablebases but rather Nalimov or Lomonosov. The 50move rule does apply in other chess composition genres though (for instance it's very much the case in retrograde analysis where many problems are based around it).
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Answers.LastEditDate: 2018-01-27T19:37:46.350Z
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Body: <p>Except for the variations where there is a capture or fork possible for the defending side, is a position possible where this kind of endgame will last more than 50 moves? Is somewhere a calculation in moves done what is the worst possible situation?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-01-23T13:03:52.910Z
Comments.Text: At most 33 moves, see https://en.wikipedia.org/wiki/Bishop_and_knight_checkmate and references there.
Comments.UserDisplayName: user1583209
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-01-23T15:51:26.767Z
Comments.Text: @user1583209 : I think your comment should become an answer, as there is nothing more to say !
Comments.UserDisplayName: Evargalo
Tags: <endgame><knight-endgame><50-move-rule><bishop-endgame>
Title: Is a forced draw by 50 moves possible with Bishop and Knight endgame?
ThreadText: # Is a forced draw by 50 moves possible with Bishop and Knight endgame?
  
  (Asked by: username_0 on 2018-01-23)
  
  Except for the variations where there is a capture or fork possible for the defending side, is a position possible where this kind of endgame will last more than 50 moves? Is somewhere a calculation in moves done what is the worst possible situation?
  
  **Tags:** endgame, knight-endgame, 50-move-rule, bishop-endgame
  
  > **Comments:**
  > **username_1**: At most 33 moves, see https://en.wikipedia.org/wiki/Bishop_and_knight_checkmate and references there.  
  > **username_2**: @username_1 : I think your comment should become an answer, as there is nothing more to say !  
  
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  ## 1 answers
  
  ### Answer by username_1 on 2018-01-24. Score: 8 | Accepted answer
  
  It takes at most 33 moves to win this endgame from any position (excluding positions where bishop or knight can be captured). See <https://en.wikipedia.org/wiki/Bishop_and_knight_checkmate> and references there.
  
  So, no, a forced draw is not possible in this endgame. However if the defending side is playing perfectly (e.g. an engine with tablebase), it could be very hard to win this for a human within 50 moves if you start from one of those 33-moves-to-mate positions.
  
  > **Comments:**
  > **username_3**: I would not say that it;s hard in terms of technique, but humans get tired, and a single slip can cost you 5 or 6 moves.  
  > **username_1**: @username_3 That's exactly what I wrote: *hard to win ... within 50 moves*.  As for technique, indeed, it is pretty easy once you know how the knight is supposed to move...  
  > **username_3**: Many years ago Scientific America had a brief note about the old Q of whether in general  R+B could win against 2 Knights, with no pawns or other pieces left (except of course the Kings). Regressive analysis by computer (basically analyzing backwards from winning positions) said YES, but only if the 50-move rule is waived. The longest variation took 233 moves to a forced win of one of the Knights, followed by about 20 more moves to mate  
  > **username_4**: The following ending even requires 545 moves to be won by white : W: Kd3 Qh1 Nh2  vs B: Kf4 Ra7 Bd1 Nh7 with black to play.  
  > **username_4**: Important to know as well : in chess endgame studies, the 50move rule doesn't apply (unless expressedly specified, but it 's rarely the case). Many engame studies have some secondary lines whose validity depends of some tablebase result giving a win longer than 50 DTZ. That s why usually composers don't use syzygy tablebases but rather Nalimov or Lomonosov. The 50move rule does apply in other chess composition genres though (for instance it's very much the case in retrograde analysis where many problems are based around it).  
  
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