Project management represents a project as a network of activities (tasks) and events (milestones marking an activity’s start or completion), used to schedule and analyze the project’s timeline.
Activity
A task consuming time and resources. Represented as an arrow between 2 events.
- Predecessor
An activity that must finish before another can start. - Dummy activity
Consumes 0 time and resources. Added only to preserve correct precedence when 2 activities share the same start and end events, or to represent a precedence relationship the diagram couldn’t otherwise express.
Event
An instantaneous point in time marking the start or completion of one or more activities. Represented as a node.
Network Construction Rules
- Every activity has exactly one start and one end event.
- No 2 activities can share both the same start and end event (use a dummy activity to separate them).
- The network must have no cycles: an event can’t depend on an activity that (directly or indirectly) depends on it.