Step 1 Select a job which has no predecessors and place it on the top of the list. Step 2 Delete the job just placed from the predecessor list of all remaining jobs. Step 3 Identify any New sources (jobs without predecessors) so generated for placement on the list and go to step 2. Step 4 Continue until one of the following happens: (a) There are no sources on the list of remaining jobs. This shows the presence of an inconsistency. (b) All jobs are placed on the list, which is now topologically ordered, showing there are no inconsistencies.
CONSISTENCY AND REDUNCANCY IN PROJECT NETWORK CONCEPT Project network should be consistent and also it is desirable that there is no redundancies in the project network Define Consistency Consistency is define as that a any project network should not contain any loop / cycles CONSISTENCY CHECK a d c 1 b e Define Inconsistency Inconsistency is define as that a project network which contain a loop or cycles Inconsistency network Presence of the loop A-C-B shows an inconsistency or logical errors in the network d a c b e METHODS OF CONSISTENCY CHECKING Topological ordering of activities Fulkerson’s numbering rule Squaring adjacency matrix Marimont’s procedure TOPOLOGICAL ORDERING Step Select a job which has no predecessors and place it on the top of the list Step Delete the job just placed from the predecessor list of all remaining jobs Step Identify any New sources (jobs without predecessors) so generated for placement on the list and go to step Step Continue until one of the following happens: (a) There are no sources on the list of remaining jobs This shows the presence of an inconsistency (b) All jobs are placed on the list, which is now topologically ordered, showing there are no inconsistencies EXAMPLE Job Predecessor a4 a1 a1 -a2 a3 a1 a4 a1 a5 a2,a3 a3 a5 a2 Topologically ordered list EXAMPLE Job Predecessor a1 a1 a3 a2 -a3 a2,a5 a4 a1,a3 a4 a5 a2 a5 a4 Inconsistent project network FULKERSON’S NUMBERING RULE Each are (i,j) of the project network is numbered Such that i