majka@ubc-visi (11/03/83)
From: Marc Majka <majka@ubc-vision.UUCP> A Turing machine is a theoretical model of computation. <speaker.umcp-cs@CSnet-Relay> points out that all this noise about "simultaneous events" is OUTSIDE of the notion of a Turing machine. Turing machines are a theoretical formulation which gives theoreticians a formal system in which to consider problems in computability, decidability, the "hardness" of classes of functions, and etc. They don't really care whether set membership in a class 0 grammer is decidable in less than 14.2 seconds. The unit of time is the state transition, or "move" (as Turing called it). If you want to discuss time (in seconds or meters), you are free to invent a new model of computation which includes that element. You are then free to prove theorems about it and attempt to prove it equivalent to other models of computation. Please do this FORMALLY and post (or publish) your results. Otherwise, invoking Turing machines is a silly and meaningless exercise. Marc Majka