When the workflow tasks are grouped in a set, it is called as worklet. Workflow tasks includes timer, decision, command, event wait, mail, session, link, assignment, control etc.
ROLAP eg.BO, MOLAP eg.Cognos, HOLAP, DOLAP
Option for incremental aggregation is enabled whenever a session is created for a mapping aggregate. Power center performs incremental aggregation through the mapping and historical cache data to perform new aggregation calculations incrementally.