The primary function of the cerebellum is to maintain posture and balance. When we jump to the side, reach forward, or turn suddenly, it subconsciously evaluates each movement. The cerebellum then sends signals to the cerebrum, indicating muscle movements that will adjust our position to keep us steady.
The Ackermann function is a classic example of a recursive function, notable especially because it is not a primitive recursive function. It grows very quickly in value, as does the size of its call tree.
An ACD is a computer telephony function associated with automatic phone answering systems. In computer telephony, an ACD (Automatic Call Distributor) is a system that automatically distributes phone calls to a specific group of agent work stations.