title: What is the difference between "someValuesFrom" and "allValuesFrom"?
body: <p>In description logic, what is the difference between "someValuesFrom" and "allValuesFrom"?
  In other words, the difference between (limited existential quantification) and (value restriction).</p>
  
  <p>For example, consider this:</p>
  
  <p>∆ = {a, b, c, d, e}<br>
     ext(B) = {&lt;c,d>}<br>
     ext(R) = {&lt;a,b>, &lt;a,c>, &lt;d,c>, &lt;c,e>}</p>
  
  <p>So what is the difference between the following?</p>
  
  <p>ext(∃R. B) = <em>?</em><br>
     ext(∀R. B) = <em>?</em></p>
  
  <p>Is there any way to simplify the concept of somevaluefrom and allvaluesfrom?</p>