Role mining to define common access patterns is the task that is performed in the planning phase of a Role Based Access Control (RBAC) implementation, and it is the most critical task in this phase. RBAC is a type of access control that grants or denies access to a system or a resource based on the roles that are assigned to the users. Roles are the collections of permissions or privileges that correspond to the functions or the responsibilities of the users in the organization. Role mining is a technique that involves analyzing the existing user accounts and their access rights, and identifying the common access patterns or the similarities among them. Role mining can help define the roles and the role hierarchies that are suitable for the organization, and that can simplify and optimize the access management process. Role mining can also help reduce the complexity and the redundancy of the access rights, and improve the security and the efficiency of the RBAC system. Role mining is performed in the planning phase of the RBAC implementation, which is the phase where the objectives, the scope, the requirements, and the resources for the RBAC system are defined and established. Role mining is the most critical task in this phase, as it can affect the design, the deployment, and the operation of the RBAC system, and it can determine the success or the failure of the RBAC implementation. References: CISSP All-in-One Exam Guide, Eighth Edition, Chapter 5: Identity and Access Management, page 219.