Dummy activity is a hypothetical activity which requires zero time and zero resources for completion. Dummy arrow represents an activity with zero duration. It is represented by dotted line and is inserted in the network to clarify activity pattern under following situations:

  1. It is created to make activities with common starting and finishing events distinguishable, and
  2. To identify and maintain the proper precedence relationship between activities that are not connected by events.

Consider a situation where A and B are concurrent activities, C is dependent on A and D is dependent on both A and B. Such a situation can be handled by use of a dummy activity as follows:

Avoiding duplication of designation – In the figure ...

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