Example

Even a simple version of our Arts Centre Booking System could have 50 use cases, but a version that might still be useful may only need to implement a dozen of them. For example:

Ticket Seller:

List Event Performances, Purchase Tickets, Report Availability of Seats, Report Event Details, Show Location of Seats

Event Manager:

Add Event, Schedule New Performance

This doesn't allow reserving of seats, cancelling of events, or reporting on ticket sales, but would still give a very good idea of what the final system might be capable of.