I know that in UML, composition means that one class basically includes other with lifetime dependency,i.e. when this class is destroyed, the composing class is destroyed as well. Unlike the aggregation, the class is not shared. But then I saw - at system designers conference, this:
[A Plane]<>COMPOSITION---------[Passenger]0,1--------<>[Seat]
This would mean that if the plane is destroyed, all passengers are destroyed (so far correct) BUT the passengers then were in aggregation (or association) relation to the seat, where each set can have 0 or 1 passenger. But in this case, isnt sharing of passengers? In reality with modern languages (C# e.g.), if just the Seat holds the reference to passenger, it will still exist, no matter that the Plane class was destroyed.