The PMBOK is a collection of processes and knowledge areas that are generally accepted as the best practices within the discipline of project management. The PMBOK structures project management processes into five basic groups known as process groups: initiating, planning, executing, monitoring and controlling, and closing. Five basic process groups are executed in each project phase of the project lifecycle, and the application of these process groups is iterative in such a way that the closing of a phase enables the initiation of the following phase. Within each process group, the individual processes can be described by their inputs (e.g., requirement definition, software requirement specification), the tools and techniques that can be applied (e.g., cost estimation techniques, work-breakdown structure, object-oriented techniques) and the resulting outputs (e.g., development plan, quality plan, complete functional coding), all of which are known as software artefacts in a software project. These Project Management Process Groups also comprise 42 management processes that describe activities throughout a project’s life cycle. These management processes include the tools and techniques used for applying knowledge and skills described in the nine knowledge areas, namely project integration management, project scope management, project time management, project cost management, project quality management, project human resource management, project communication management, project risk management and project procurement management. Maybe from my description you can identify the co-relationship.