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Types Of Dependencies

The sequence of activities can be based on multiple dependencies. Some of them are listed below:

  • Mandatory Dependency (Hard Logic):

A mandatory dependency is a natural flow of work being done (e.g. you must give the command to print before you can print). It may be required by the contract.

  • Discretionary Dependency (Preferred, Preferential, or Soft Logic):

A project team cannot easily change other types of dependencies. However, they can change the discretionary dependency. A discretionary dependency is determined by the project manager and the project team. Discretionary dependency is quite useful when there is a need to compress the project schedule or fast track the project.

  • External Dependency:

Parties outside the project can also influence the project. External Dependency is based on the needs of a party outside the project (e.g. labor union, regulators, etc)


A lead may be used to indicate that an activity can start before its predecessor activity is completed. For example, editing of a book may start before the write-up is finished.


A lag is inserted by waiting time between activities, such as requiring to wait for completion of the application testing before the final roll-out of an application. Sequence Activities process may also result in the identification of new risks. It may also lead to updates to activity list and activity attributes.