Answers.Body: <p>It's likely due to Stockfish's transposition table (essentially a fast lookup table that Stockfish can use to refer back to positions it evaluated before). During your first run, information about visited positions was stored in the table. Then on the second run, Stockfish may have looked at some of Black's moves after depth 1 (since it's already evaluated all states at depth 1).</p>
  
  <p>SmallChess' answer to this question may be useful if it's still confusing:</p>
  
  <p><a href="https://chess.stackexchange.com/questions/14021/how-to-read-score-from-stockfish-inconsistent-response-every-call">How to read score from stockfish - inconsistent response every call?</a></p>
  
  <p>Edit: to test if it is the transposition table behind this, try to reset it after the first run (close the whole program if you can't figure out how). Then on the second run, the number of nodes should be the same (as well as the centipawn evaluation).</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-05-08T01:36:27.720Z
Answers.Text: "Then on the second run, Stockfish may have looked at some of Black's moves after depth 1". I think that Black's moves belong to depth 2, and there are 20 nodes at depth 1, because White has 20 legal moves from the original position. You are explaining that the node 21st is a Black's move right? If it's a Black's move, how can it belong to depth 1, because it must belong to depth 2.
Answers.UserDisplayName: hdvd2309
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-05-08T01:39:49.260Z
Answers.Text: @hdvd2309 Yes, it doesn't technically belong to depth 1. When an engine says depth 1, it means searching that far in conjunction with other tools. One of these tools is a transposition table, another is quiescence search (i.e., if a position is too wild, keep searching ahead and evaluate successor nodes).
Answers.UserDisplayName: Inertial Ignorance
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2020-05-07T10:26:48.937Z
Answers.LastActivityDate: 2020-05-07T10:26:48.937Z
Answers.UserDisplayName: Inertial Ignorance
Body: <p>I ran Stockfish 2 times with the command <code>go depth 1</code>.</p>
  
  <p>First time</p>
  
  <pre><code>info depth 1 seldepth 1 multipv 1 score cp 114 nodes 20 nps 10000 tbhits 0 time 2 pv e2e3
  </code></pre>
  
  <p>Second time:</p>
  
  <pre><code>info depth 1 seldepth 1 multipv 1 score cp 105 nodes 22 nps 22000 tbhits 0 time 1 pv e2e4
  </code></pre>
  
  <p>Why does the number of nodes increase from 20 to 22?</p>
  
Tags: <stockfish>
Title: Stockfish: different nodes numbers with identical calls
ThreadText: # Stockfish: different nodes numbers with identical calls
  
  (Asked by: username_0 on 2020-05-07)
  
  I ran Stockfish 2 times with the command `go depth 1`.
  
  First time
  
  ```
  info depth 1 seldepth 1 multipv 1 score cp 114 nodes 20 nps 10000 tbhits 0 time 2 pv e2e3
  
  ```
  
  Second time:
  
  ```
  info depth 1 seldepth 1 multipv 1 score cp 105 nodes 22 nps 22000 tbhits 0 time 1 pv e2e4
  
  ```
  
  Why does the number of nodes increase from 20 to 22?
  
  **Tags:** stockfish
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2020-05-07. Score: 1
  
  It's likely due to Stockfish's transposition table (essentially a fast lookup table that Stockfish can use to refer back to positions it evaluated before). During your first run, information about visited positions was stored in the table. Then on the second run, Stockfish may have looked at some of Black's moves after depth 1 (since it's already evaluated all states at depth 1).
  
  SmallChess' answer to this question may be useful if it's still confusing:
  
  [How to read score from stockfish - inconsistent response every call?](https://chess.stackexchange.com/questions/14021/how-to-read-score-from-stockfish-inconsistent-response-every-call)
  
  Edit: to test if it is the transposition table behind this, try to reset it after the first run (close the whole program if you can't figure out how). Then on the second run, the number of nodes should be the same (as well as the centipawn evaluation).
  
  > **Comments:**
  > **username_0**: "Then on the second run, Stockfish may have looked at some of Black's moves after depth 1". I think that Black's moves belong to depth 2, and there are 20 nodes at depth 1, because White has 20 legal moves from the original position. You are explaining that the node 21st is a Black's move right? If it's a Black's move, how can it belong to depth 1, because it must belong to depth 2.  
  > **username_1**: @username_0 Yes, it doesn't technically belong to depth 1. When an engine says depth 1, it means searching that far in conjunction with other tools. One of these tools is a transposition table, another is quiescence search (i.e., if a position is too wild, keep searching ahead and evaluate successor nodes).  
  
  ---
  
  