Answers.Body: <p>To get the ball rolling, from the following position the first 6 moves for each side are forced in order not to lose. (If <code>7.h8=B</code> weren't available and <code>7.h8=Q</code> needed to be played, then the forced follow-ups <code>7...h1=Q+ 8.Qxa1+ Kxa1</code> would extend it to 8, but no cigar.)</p>
  
  <pre><code>[FEN "K5R1/8/p7/8/8/7P/8/1q1k4 w - - 0 1"]
  
  1.Rg1+ $1 Kc2 $1 2.Rxb1 $1 Kxb1 $1 3.h4 $1 a5 $1 4.h5 $1 a4 $1 5.h6 $1 a3 
  $1 6.h7 $1 a2 $1 7.h8=Q 
      ( 7.h8=B )
  7...a1=Q+ $1 8.Qxa1+ $1 Kxa1 $1 *
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-03-11T23:17:58.237Z
Answers.Text: already pretty good!
Answers.UserDisplayName: Peter
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2023-05-29T15:44:59.590Z
Answers.Text: Don't you get half a cigar if you replace the BPa6 by a bPd6 ? Then 7.h8Q and 7...d1Q are forced too.
Answers.UserDisplayName: Evargalo
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-03-11T22:35:28.197Z
Answers.LastActivityDate: 2015-03-11T22:35:28.197Z
Answers.UserDisplayName: ETD
Answers.Body: <p>In the <a href="http://matplus.net/start.php?px=1584295518&amp;app=forum&amp;act=posts&amp;fid=xshowm&amp;tid=2324" rel="nofollow noreferrer">Matplus.net forums,</a> Arpad Rusz shared the longest such sequence in a 6-piece position. The length of it is 19 plies.</p>
  <p>You can check the uniqueness for yourself by using the <a href="https://syzygy-tables.info/?fen=3k4/8/8/p4pP1/3K3P/8/8/8_w_-_-_0_1" rel="nofollow noreferrer">Sygyzy tablebases.</a>.</p>
  <pre><code>[FEN &quot;3k4/8/8/p4pP1/3K3P/8/8/8 w - - 0 1&quot;]
  
  1. h5 Ke7 2. h6 Kf7 3. Ke5 Kg6 4. Ke6 f4 5. h7 Kxh7 6. Kf7 f3 7. g6+ Kh6 8. g7 f2 9. g8=Q f1=Q+ 10. Ke7
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-06-11T12:10:12.180Z
Answers.LastActivityDate: 2021-07-01T17:12:07.107Z
Answers.LastEditDate: 2021-07-01T17:12:07.107Z
Answers.UserDisplayName: Rewan Demontay
Answers.Body: <p>do you mean this position? </p>
  
  <pre><code>2Q5/8/8/8/3n4/8/1b6/k2K4 b - - 0 1
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-03-11T19:46:31.383Z
Answers.Text: No, BOTH sides must have only one move to draw.
Answers.UserDisplayName: Peter
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2015-03-11T19:32:56.920Z
Answers.LastActivityDate: 2015-03-11T21:57:45.300Z
Answers.LastEditDate: 2015-03-11T21:57:45.300Z
Answers.UserDisplayName: user5649
Body: <p>What is the longest known sequence of moves with upto 6 pieces where each move of
   both sides is the only move drawing the game (any other move would lose the game) ?</p>
  
  <p>There should not occur any repitition of a position.</p>
  
  <p>I experimented with the endgame rook vs two (three) pawns and got some
   sequences I unfortunately do not remember.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-06-27T00:24:47.613Z
Comments.Text: I truly wish (but doubt) that this is true of the starting position.
Comments.UserDisplayName: DongKy
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-06-27T14:57:48.503Z
Comments.Text: The starting position may well be a draw, but I highly doubt that all starting moves but one are a forced win for Black :)
Comments.UserDisplayName: D M
Tags: <endgame><draw><tablebases><records>
Title: Longest sequence with only moves to draw without a repetition
ThreadText: # Longest sequence with only moves to draw without a repetition
  
  (Asked by: username_0 on 2015-03-11)
  
  What is the longest known sequence of moves with upto 6 pieces where each move of
  both sides is the only move drawing the game (any other move would lose the game) ?
  
  There should not occur any repitition of a position.
  
  I experimented with the endgame rook vs two (three) pawns and got some
  sequences I unfortunately do not remember.
  
  **Tags:** endgame, draw, tablebases, records
  
  > **Comments:**
  > **username_1**: I truly wish (but doubt) that this is true of the starting position.  
  > **username_2**: The starting position may well be a draw, but I highly doubt that all starting moves but one are a forced win for Black :)  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_3 on 2015-03-11. Score: 3
  
  To get the ball rolling, from the following position the first 6 moves for each side are forced in order not to lose. (If 7.h8=B weren't available and 7.h8=Q needed to be played, then the forced follow-ups 7...h1=Q+ 8.Qxa1+ Kxa1 would extend it to 8, but no cigar.)
  [FEN "K5R1/8/p7/8/8/7P/8/1q1k4 w - - 0 1"]
  
  1.Rg1+ $1 Kc2 $1 2.Rxb1 $1 Kxb1 $1 3.h4 $1 a5 $1 4.h5 $1 a4 $1 5.h6 $1 a3 
  $1 6.h7 $1 a2 $1 7.h8=Q 
      ( 7.h8=B )
  7...a1=Q+ $1 8.Qxa1+ $1 Kxa1 $1 *
  
  > **Comments:**
  > **username_0**: already pretty good!  
  > **username_4**: Don't you get half a cigar if you replace the BPa6 by a bPd6 ? Then 7.h8Q and 7...d1Q are forced too.  
  
  ---
  
  ### Answer by username_5 on 2019-06-11. Score: 3
  
  In the Matplus.net forums, Arpad Rusz shared the longest such sequence in a 6-piece position. The length of it is 19 plies.
  You can check the uniqueness for yourself by using the Sygyzy tablebases..
  [FEN "3k4/8/8/p4pP1/3K3P/8/8/8 w - - 0 1"]
  
  1. h5 Ke7 2. h6 Kf7 3. Ke5 Kg6 4. Ke6 f4 5. h7 Kxh7 6. Kf7 f3 7. g6+ Kh6 8. g7 f2 9. g8=Q f1=Q+ 10. Ke7
  
  
  ---
  
  ### Answer by username_6 on 2015-03-11. Score: -1
  
  do you mean this position? 
  2Q5/8/8/8/3n4/8/1b6/k2K4 b - - 0 1
  
  > **Comments:**
  > **username_0**: No, BOTH sides must have only one move to draw.  
  
  ---
  
  