Answers.Body: <p>It does what it was programmed to do.  During any Alpha-Beta pruning, the computer would stop searching and just do nothing.</p>
  <p>In another game, like an RTS, the computer would constantly go through a todo list.
  What should/can I build?
  What should/can I produce?
  How do I defend/attack?
  ...</p>
  <p>Since a chess AI has only one objective, find the best move, there's no point in searching once it's objective if found.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-03-25T03:10:21.737Z
Answers.Text: This answer seems reasonable, but is easily shown to be nonsense. I copied the position into Scid, equipped with Stockfish, and started the engine. It immediately outputted 127 lines from `1 M1 1.Qh7#  (0.00)` to `127 M1 1.Qh7#  (0.00)`, but then continued to grab as many CPU cycles as it could get (sometimes its CPU usage was literally 100%, as shown in my task manager) until I stopped it. I would also like to know what Stockfish is actually doing here.
Answers.UserDisplayName: Brian Drake
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-03-25T03:14:05.427Z
Answers.Text: It gets worse! I tried manually playing Qh7# before running Stockfish, and it *still* hogged the CPU until I stopped it!
Answers.UserDisplayName: Brian Drake
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-03-25T08:05:35.507Z
Answers.Text: With M1 the score shouldn't be 0.  [jk]  Maybe the computer became sentient and is planning how to most efficiently destroy the inferior creatures of its creators.
Answers.UserDisplayName: Mike Jones
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-03-23T16:34:53.623Z
Answers.LastActivityDate: 2021-03-23T16:34:53.623Z
Answers.UserDisplayName: Mike Jones
Body: <p>For example, take this famous position from Kramnik vs. Deep Fritz, 2005:</p>
  <pre><code>[FEN &quot;5N1k/6p1/7p/4P3/pp2Q3/4q3/1P4PP/2b4K w - - 0 1&quot;]
  </code></pre>
  <p>Obviously White wins with Qh7#, and equally obviously, there are no possible better moves (since it's impossible to have a mate in 0).</p>
  <p>If I let an engine run on this position, what does it do after finding the mate in 1? There's presumably nothing else to do since it has already found <em>the</em> best move. Does it just exit, then?</p>
  <p>I tried running Stockfish 13 on this position, and it reaches depth 99/99 instantly, but I can't tell what it's doing afterwards.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-03-23T13:51:48.650Z
Comments.Text: I once designed an engine for connect four, and I programmed it that if it found the best possible move, it didn’t keep checking but it immediately stopped.
Comments.UserDisplayName: fartgeek
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-03-23T22:57:46.020Z
Comments.Text: once stockfish reaches maximum depth it just stops the search
Comments.UserDisplayName: Sopel
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-03-25T03:16:25.037Z
Comments.Text: @Sopel This is an answer, and should be posted as such. It is also incorrect, if 100% CPU usage by Stockfish is any guide. See my comments on the existing answer.
Comments.UserDisplayName: Brian Drake
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-03-26T01:27:16.900Z
Comments.Text: Related: https://chess.stackexchange.com/q/21479/25131
Comments.UserDisplayName: Brian Drake
Tags: <engines><checkmate>
Title: What does an engine do if it has found the shortest mate?
ThreadText: # What does an engine do if it has found the shortest mate?
  
  (Asked by: username_0 on 2021-03-23)
  
  For example, take this famous position from Kramnik vs. Deep Fritz, 2005:
  [FEN "5N1k/6p1/7p/4P3/pp2Q3/4q3/1P4PP/2b4K w - - 0 1"]
  
  Obviously White wins with Qh7#, and equally obviously, there are no possible better moves (since it's impossible to have a mate in 0).
  If I let an engine run on this position, what does it do after finding the mate in 1? There's presumably nothing else to do since it has already found the best move. Does it just exit, then?
  I tried running Stockfish 13 on this position, and it reaches depth 99/99 instantly, but I can't tell what it's doing afterwards.
  
  **Tags:** engines, checkmate
  
  > **Comments:**
  > **username_1**: I once designed an engine for connect four, and I programmed it that if it found the best possible move, it didn’t keep checking but it immediately stopped.  
  > **username_2**: once stockfish reaches maximum depth it just stops the search  
  > **username_3**: @username_2 This is an answer, and should be posted as such. It is also incorrect, if 100% CPU usage by Stockfish is any guide. See my comments on the existing answer.  
  > **username_3**: Related: https://chess.stackexchange.com/q/21479/25131  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_4 on 2021-03-23. Score: 4 | Accepted answer
  
  It does what it was programmed to do. During any Alpha-Beta pruning, the computer would stop searching and just do nothing.
  
  In another game, like an RTS, the computer would constantly go through a todo list.
  What should/can I build?
  What should/can I produce?
  How do I defend/attack?
  ...
  
  Since a chess AI has only one objective, find the best move, there's no point in searching once it's objective if found.
  
  > **Comments:**
  > **username_3**: This answer seems reasonable, but is easily shown to be nonsense. I copied the position into Scid, equipped with Stockfish, and started the engine. It immediately outputted 127 lines from `1 M1 1.Qh7#  (0.00)` to `127 M1 1.Qh7#  (0.00)`, but then continued to grab as many CPU cycles as it could get (sometimes its CPU usage was literally 100%, as shown in my task manager) until I stopped it. I would also like to know what Stockfish is actually doing here.  
  > **username_3**: It gets worse! I tried manually playing Qh7# before running Stockfish, and it *still* hogged the CPU until I stopped it!  
  > **username_4**: With M1 the score shouldn't be 0.  [jk]  Maybe the computer became sentient and is planning how to most efficiently destroy the inferior creatures of its creators.  
  
  ---
  
  