The precedence graph is the most important part of ProBalance. This graph depicts the order in which the activities (tasks) must to be done. The ProBalance task assignments are strictly followed using this precedence graph(Figure 1).
| 1. | Zoom Controls |
| 2. | Default Assignment |
| 3. | Auto Arrange |
| 4. | Precedence Graph |
| 5. | Text Editor |
| 6. | Cluster List |
| 7. | View Type |
| • | Based on the tasks listed in the task sheet, corresponding number of nodes (yellow circles) will be drawn in the precedence graph. The user has to draw arcs between the nodes to depict the order in which the tasks should be done. |
| • | Clicking the default icon (2) will align all tasks in one straight line, indicating that the tasks are to be done one after the other. The auto arrange icon (3) re-draws the graph in an organized manner. |
| • | Task ID's, Task Descriptions or Task ID's & Descriptions can be displayed on the Task nodes within the Precedence graph. These Task Display settings can be changed from the Precedence option on the Edit menu in the top left corner of ProBalance. |
Editing the Precedence Graph
Editing Task Nodes
The Precedence graph can be edited in two ways:
| 1. | Editing the graph - The user has to draw arcs between the nodes to depict the order in which the tasks should be done. In order to draw an arc move the cursor to the center of the node - the cursor changes to the hand icon, next click on the center and drag the cursor to the node to which the arc has to be drawn to and release the click. |
| 2. | Using the text editor - Each task in the precedence graph has a task number assigned to it. In order to textually define a graph, the user has to provide task numbers of its preceding tasks. Note in the image below, Metal Cutting and Welding are done before the Hole Punch task. |
 Figure 2: Precedence graph example |
 Figure 3: Corresponding entry in text editor |
Clusters are sets of tasks that the user can create. The user can define a precedence relationship for tasks within the cluster and later define a precedence relation between the clusters too.
| 1. | In order to create a cluster, change the view type to Cluster. |
| 2. | The user will see a default cluster present, in order to add new clusters, type the cluster name in the cluster column. |
| 3. | Once the clusters have been created, save the list. |
| 4. | At this stage the user can define a precedence relationship among the clusters. |
| 5. | Next, change the view type to Task Graph. |
| 6. | Next to each task in the list below, the user can now provide the cluster this task belongs to. |
| 7. | Once the tasks have been assigned a cluster, click on the cluster drop down. The user will now see all the clusters listed here. |
| 8. | Select the cluster to be edited from this list, the corresponding nodes appear below. The user can now draw arcs or define the precedence by providing a task number in the predecessor column. |