  We derive an abstract computational model from a sequential computational
model that is generally used for function execution. This abstract
computational model allows for the concurrent execution of functions. We
discuss concurrent models for function execution as implementations from the
abstract computational model. We give an example of a particular concurrent
function construct that can be implemented on a concurrent machine model using
multi-threading. The result is a framework of computational models at different
levels of abstraction that can be used in further development of concurrent
computational models that deal with the problems inherent with concurrency.
