ABSTRACT
This chapter begins with some observations that date back to Bertrand Russell and Norbert Wiener concerning “interval orderings” and time. It investigates finiteness conditions and defines system executions. The chapter discusses higher and lower-level events. Then the chapter also analyzes the paradox of Achilles and the Tortoise and its relation with the finiteness condition. Modeling is not only an abstract description of reality, but also a simplification which disregards some non-essential features. A global-time model reflects only the temporal order type of the system run and no other information. The global-time axiom is not a consequence of Lamport’s four axioms, and if it is added then the temporal picture is much simplified. Communication devices with their external operations are used by the processes to obtain information from the outside and to change the environment.
