Network diagram

      It is a graphical representation of the logical sequence. In which different activities are interrelated to each other while completing the project.

Rules for network diagram :-
1. An activity can only be started when all the activities earlier to it are completed.

2. No two or more activities may have same head and tail event.

  

    In this condition to represent the same logic we need to use dummy activities.

Dummy activity :- an activity which only shows the relation and logic and dependency of one activity over the another but doesn't consume only time or resource for its completion is termed as dummy activity. It represent as dotted line.

  

                        -------------->

3. Intersecting of activities are represented by

     

4. Dummy activities should only the used when it is very necessary but their is no restriction on the number of dummy activities used.

5. There should be no looping and dangling in  the network diagram.

Dangling :- when activity other then the final activity do not have any successor activities then the situation are called dangling.

Example :-

      Draw a network diagram from the set of activities ?

A      -

B     A

C     B

D     A

E     D

F      C,E

Answer :-  see in image.