Should the sequence diagram include classes etc. that meet the pre-conditions of the use case? Or, can I just create the sequence diagram for the use case thinking that pre-conditions are already being met and not bother showing all the classes that are required for pre-conditions in the sequence diagram itself?
So, what is the answer: Show or not show classes related to pre-conditions in the sequence diagram?
In my whole opinion, it is not a requirement to show pre-conditions as part of the sequence diagram for the listed usecases in the assignment.
In other words, you dont have to show the login sequence in your pay for itinerary usecase. If time permits you have two options a) Mention that the pre-conditions are not shown (OR) b) Draw a seperate sequence-diagram (ofcourse you wont be marked for this), to show the login sequence (which I guess is the pre-condition you are taking about).