title: Mathematica Dynamic List Manipulation
body: <p>I am stuck on what I think should be a relatively simple concept.  I am not understanding how Dynamic[] functions with regarding incremental list manipulations.  Consider the following statements:</p>
  
  <pre><code>In[459]:= x={{1,2}};
  In[462]:= y=First[x]
  Out[462]= {1,2}
  In[463]:= z=First[y]
  Out[463]= 1
  </code></pre>
  
  <p>Simple right?  Now, I want z to dynamically update when I change x.  Here is my attempt:</p>
  
  <pre><code>In[458]:= a={{1,2}};
  In[452]:= b=Dynamic[First[a]]
  Out[452]= {1,2}
  In[449]:= c=Dynamic[First[b]]
  Out[449]= {1,2}
  </code></pre>
  
  <p>As I change the values in list a, I see corresponding change is b and c; however, I would expect each statement to <strong>Part</strong> the first element.  Manipulations on Dynamic lists are not taking.</p>
  
  <p>My question is why do we see this behavior, and how can I apply consecutive Dynamic list manipulations?</p>
  
  <p>Thank you in advance.</p>