Operations 6 and 4 should be completed before the beginning of the operation 7. This reduces the time to complete the project because after operation 1, operation 2 and 3 can be started simultaneously. Hence the operations 3 and 4 can be conducted at the same time, when 2, 5 and 6 operations are being conducted. Network shows that operation 3 and 4 are not affected by operations 2, 5 and 6. The operation on the left of each line should be completed before the starting of the operations on the right of the line. 28.40 is drawn as per circle and line method in which circles represents the operation or activity and the line shows the relationship between the two activities.

If each operation is represented by a circle then this work can be executed in a better way as follows: Its logical order of operations should be E, A, D, B, F, C and G. The list of operations is given below, which is not in a logical order: First step is then to divide the project into operations. Suppose we want to start a small scale factory in a shed available in an Industrial area in which workshop is to be prepared. Also 3 and 4 will be called post operations (POST-OPR) of operations 1 and 2 respectively, 5 is the POST- OPR of operation 3 and 4. Similarly 3 and 4 both are the PRE-OPR of operation 5. In the language of C.P.M., the operations 1 and 2 are called the pre-operations (or PRE- OPR) of 3 and 4 respectively.

Also the operation 3 and 4 must immediately precede the operation 5. Thus we can say that operation 1 immediately preceding operation 3, and operation 2 immediately precedes operation 4. 28.38 that operation 5 can only begin when the operation 3 and 4 are over. All the circles in the extreme left are first numbered and so on. Thus the network is drawn from left to right and each circle representing an operation is numbered from left to right. After the end of operation C and D, the last operation of fixing nails can begin.

Sequence diagram online scheduler