created: 01/08/01; revised: 10/15/06, 07/29/07
A finite-state automaton does nothing but work its way through a string, accepting or rejecting it. A finite-state transducer (FST) is like an automaton, but it performs various actions as it consumes an input string.
Java's regular expression classes,
can be used to do many of the things that hand-coded transducers can do.
These classes are explained in future chapters.
Think of a situation where a program converts an input string into an output string.