Project Network

Work in progress. This note is still being written and incomplete.

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.
Written by September 16, 2026 1 min read
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