title: composition relationship in class diagram can have cycles?
body: <p>I want to implement a model checker for Java class diagrams.</p>
  
  <p>There are many constraints that I've been considered for a while.</p>
  
  <p>Hope anyone can help me figure it out.</p>
  
  <p>All the cycles here I mean are pure cycles with only one type of relationship.</p>
  
  <p>Q1: Suppose class A is composed of class B, is it possible that class B is also composed of class A, given that class A and class B are different classes? Moreover, is it possible for composition relationship to have cycles?</p>
  
  <p>Q2: What about other relationship in the class diagram, like aggregation, dependence and association? What's the meaning of cycles in these relationships? Can anyone give some examples?</p>
  
  <p>Thanks for reading my question and hope someone can help me out.</p>