title: What Happens when Cartesian Product is applied to Relations with same attribute name
body: <p>I understand that the Cartesian product(X) operation on two databases does not need to be UNION compatible.So,if there is a same attribute called <em>name</em> in the two relations <strong>R</strong> and <strong>S</strong> where  <em>name</em> in <strong>R</strong> is the first name and <em>name</em> in <strong>S</strong> is the second name</p>
  
  <p>How can the related values be identified by the following selection operation </p>
  
  <p><strong>Q=RxS</strong></p>
  
  <p>I want to get the set of tuples whose firstname=lastname,So how am i supposed to write the selection statement? </p>
  
  <p><strong>σ Name=Name(Q)</strong> </p>
  
  <p>Will this be a problem using the same attribute name in the selection operation?  </p>