Answers.Body: <p>Another search algorithm that produces lower and upper bounds is <a href="https://en.wikipedia.org/wiki/MTD(f)" rel="nofollow noreferrer">MTD</a>. It is basically a binary search that narrows in on the true value.</p>
  
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Answers.CreationDate: 2022-12-20T07:50:54.853Z
Answers.LastActivityDate: 2022-12-20T07:50:54.853Z
Answers.UserDisplayName: Thomas Ahle
Body: <p>I am having trouble understanding how &quot;upperbound` and &quot;lowerbound&quot; come into play in the UCI protocol.</p>
  <p>The spec says:</p>
  <blockquote>
  <ul>
  <li>lowerbound: the score is just a lower bound.</li>
  <li>upperbound: the score is just an upper bound.</li>
  </ul>
  </blockquote>
  <p>For example, I see Stockfish using it like this.</p>
  <pre><code>info depth 22 seldepth 27 multipv 1 score cp 27 upperbound nodes 2567224
  </code></pre>
  <p>I kind of understand that it is related to the &quot;cp.&quot; But I don't really know how. Could someone help me clarify this? It would be best if you used an example.</p>
  
Tags: <engines><uci>
Title: Example of "lowerbound" and "upperbound" in the UCI protocol
ThreadText: # Example of "lowerbound" and "upperbound" in the UCI protocol
  
  (Asked by: username_0 on 2021-07-09)
  
  I am having trouble understanding how "upperbound` and "lowerbound" come into play in the UCI protocol.
  
  The spec says:
  
  > * lowerbound: the score is just a lower bound.
  > * upperbound: the score is just an upper bound.
  
  For example, I see Stockfish using it like this.
  
  ```
  info depth 22 seldepth 27 multipv 1 score cp 27 upperbound nodes 2567224
  
  ```
  
  I kind of understand that it is related to the "cp." But I don't really know how. Could someone help me clarify this? It would be best if you used an example.
  
  **Tags:** engines, uci
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2022-12-20. Score: 0
  
  Another search algorithm that produces lower and upper bounds is [MTD](https://en.wikipedia.org/wiki/MTD(f)). It is basically a binary search that narrows in on the true value.
  
  
  ---
  
  