Multi-component architectures are architectures which are designed in physically seperate pieces. These pieces may correspond to functional divisions, but do not necessarialy have to. An extreme example of multi- component architectures is the Subsumption (R.A.Brooks) architecture, where each individual behvior is a physically seperate processor , and each of such behaviors can operate on the environment independant of the other layers. Most component architectures decompose the system into functional pieces in order to reduce the overall complexity each must deal with, such as seperate perception, action, and cognition systems. An example of such a system is Icarus (P. Langly) , which has seperate planning,action, perception, and memory components. There is an emerging subclass of multi-component architectures which are composed of 3 distinct components. These components are, usually a planner, a scheduler, and an executor and the prototypical architecture is the ERE (Drummond,M et.al.) architecture.