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Turing's World: Other Machines

Turing's World also lets you construct several other kinds of machines that are important in computability theory: one-way and two-way finite-state machines (finite automata), and non-deterministic Turing and finite-state machines.

Here, for example, is a non-deterministic, one-way finite-state machine. This machine "accepts" input strings that have either a string of four consecutive A's or three consecutive B's.

Unlike a normal Turing machine, a non-deterministic machine can do more than one thing in a given state when reading a given input symbol. This means that the machine's computation can simultaneously follow more than one path through its state diagram. To show such a computation, Turing's World produces multiple tapes, one for each path the computation follows. Below is an image of a non-deterministic computation in progress.


Turing's World Table of Contents.

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