In the Sequence Activities process described in the PMBOKGuide, the Precedence Diagramming Method (PDM) defines four types of logical relationships (dependencies) between activities.
* Finish-to-Start (FS) (Choice C): This is the most commonly used relationship type. It dictates that a successor activity (painting) cannot start until a predecessor activity (plastering) has finished. In this scenario, the painter explicitly states they cannot start because the mason has not finished; this is a classic " Finish-to-Start " dependency.
* Finish-to-Finish (FF) (Choice A): A successor activity cannot finish until a predecessor activity has finished. For example, a document cannot be finished being edited until the draft is finished being written.
* Start-to-Start (SS) (Choice D): A successor activity cannot start until a predecessor activity has started.
This is often used for activities that can occur in parallel once the first one begins.
* Start-to-Finish (SF) (Choice B): A successor activity cannot finish until a predecessor activity has started. This is the rarest relationship type and is seldom used in construction projects.
In construction logic, physical dependencies-such as needing a wall to be plastered before it can be painted- are almost always modeled as Finish-to-Start relationships to ensure a logical and high-quality sequence of work.