An activity scheme designer may associate an activity scheme with a task of a process model that includes a plurality of tasks, the activity scheme including a directed graph of nodes in which the nodes represent knowledge actions to be performed at least partially by human users, and in which edges of the directed graph connecting the nodes are probabilistically weighted. A workflow engine may instantiate the process model for execution, including associating an instance of the task with a user of the human users, the task instance including instance-specific data associated with completing the execution. An activity scheme transformer may transform the activity scheme for the user, based on the instance-specific data, a context of the user including applications and information resources available to the user, and a personal profile of the user.