[donh]

For lurkers, a finite state machine is like a soda vending machine. As sufficient coins are entered, the state changes and you get a soda.

A useful way to think about FSM's, as opposed to more powerful parsing devices, is that an FSM knows instantly when it has succeeded or failed, without the aid of a memory store.

Here's my favorite chart on the subject:

Language Class -- Chomsky level -- recognition automata

recursively enumerable -- 0     -- Turing Machine
context-sensitive      -- 1     -- linearly bound TM
context-free           -- 2     -- push down automata
regular                -- 3     -- Finite State Machine

Tokenizers are generally FSM's/regular grammars, commercial compilers are generally PDA's/CFG's, and semantic processing is, well, beyond my ken, formally speaking.

[f.Christian]

xm...

There are only 4 possible answers to the origins of the universe: It sprang from NOTHING (impossible since nothing cannot produce anything); it has existed eternally (impossible because of the dimension of "time" and "entropy" - the universe cannot "wind down" forever); it is an illusion (let's not even go there since this is an indefensible position); or, it was created by a creator out of nothing. Take your pick. Which is it?

[Alamo-Girl]

Thank you so much for the very helpful chart! Hugs!

BTW, have you ever written a compiler or interpreter?