title: How to find multivalued dependencies that not satisfy R?
body: <p>I'm currently taking the course on DB and the theme is Relational Design Theory. Sub-theme is Multivalued dependencies and I'm completely lost in them :(</p>
  
  <p>I have such a question:</p>
  
  <pre><code>R(A,B,C):
  A | B | C
  ----------
  1 | 2 | 3
  1 | 3 | 2
  1 | 2 | 2
  3 | 2 | 1
  3 | 2 | 3
  </code></pre>
  
  <p>Which of the following multivalued dependencies does this instance of R not satisfy?</p>
  
  <pre><code>1. AB ↠ C 
  2. B ↠ C 
  3. C ↠ A 
  4. BC ↠ C
  </code></pre>
  
  <p>I know that:</p>
  
  <pre><code>A | B  | rest
  ----------
  a | b1 | r1
  a | b2 | r2
  a | b1 | r2
  a | b2 | r1
  </code></pre>
  
  <p>I'm making tables for those dependencies in those manner:</p>
  
  <pre><code>B ↠ C
  
  B | C | A
  ----------
  2 | 3 | 1
  2 | 2 | 1
  2 | 1 | 3
  2 | 3 | 3
  3 | 2 | 1
  </code></pre>
  
  <p>According to my assumptions:
  <code>2 2 1</code> and <code>2 1 3</code> are at rule above, so there also should be <code>2 1 1</code> and <code>2 2 3</code> records.</p>
  
  <p>So this one is not correct. Am I right?</p>
  
  <p>And I don't have any idea how to build such table for <code>AB ↠ C</code>. It will be the same table?</p>
  
  <pre><code>A | B | C
  ----------
  1 | 2 | 3
  1 | 3 | 2
  1 | 2 | 2
  3 | 2 | 1
  3 | 2 | 3
  </code></pre>
  
  <p>Is it something that called trivial dependency?</p>