In project management, tasks are dependent on other tasks. This means that tasks are related with one another. The dependency of the tasks determines the order of activities within the project schedule. Dependencies are also characterized according to its four attributes which include mandatory, discretionary, internal and external.
The mandatory dependency, also called hard logic, are those that are inherent to the project or work. They involve physical limitations such as the construction of the building cannot supersede the construction of the road as an example. Aside from physical limitations, hard logic can also involve technical limitations. Another example is to define a test case prior to testing of the product, service or result. Thus, this particular dependency indicates that Task B cannot proceed unless the requirements of Task A have been satisfied.
It is the role of the project team to determine which activities or dependencies are mandatory during the process of project management planning. It is important to determine the sequence and organization of activities to avoid confusion during the implementation of the activities.
Establishing the dependencies is crucial for the project manager to plan the schedule. In most cases, the hard logic dependency always follows a structured plan or activities. This particular type of dependency is rigid and should be followed strictly. Team members cannot start from one task before the previous task has not been completed yet.
Unfortunately, this particular task relationship is highly constrained. Take note that the predecessor task should be completed even before the successor task can start. It is important to take note that this a natural constraint that all project managers following this type of dependency should deal with. This is the reason why it is so crucial for the project manager to identify all tasks effectively, set appropriate time to complete the tasks and also plan for contingency in case the task is not completed on the desired date.
This term is defined in the 5th edition of the PMBOK.