title: Check whether an array is a subset of another
body: <p>Any idea on how to check whether that list is a subset of another?</p>
  
  <p>Specifically, I have</p>
  
  <pre><code>List&lt;double&gt; t1 = new List&lt;double&gt; { 1, 3, 5 };
  List&lt;double&gt; t2 = new List&lt;double&gt; { 1, 5 };
  </code></pre>
  
  <p>How to check that t2 is a subset of t1, using LINQ?</p>