title: structural equivalence vs name equivalence
body: <p>I can't seem to grasp exactly what name equivalence is. I'm pretty sure I have structural down though. An example my professor gave was this:</p>
  
  <pre><code> Type TI=integer
   Type TTI=TI
  
   a=integer
   b=TTI
   f= ref float
   g= ref float
  </code></pre>
  
  <p>a and b are both structural and name equivalent, while f and g are just structural equivalent.I don't understand why a and b would be name equivalent, but f and g aren't.</p>