title: Algorithmic representation of list of list
body: <p>I am creating a list with the elements of another list. I want to make sure about two things. First that the list is made from another list and second the size of list changes. Is the following representation good enough ? </p>
  
  <pre><code>n ∈ {2,3,4}
  new_list = [list[1], ... , list[n]]
  </code></pre>
  
  <p>How can I represent algorithmically that I create the "new_list" with elements of "list" without the dots ? </p>