Math and science::Theory of Computation
Alphabets and languages
An alphabet is defined to be any nonempty finite set. The members of an alphabet are the symbols of the alphabet.
A string over an alphabet is a finite sequence of symbols from that alphabet.
A language is a set of strings. A language is prefix-free if no member is a proper prefix of another.
A string is a proper prefix of another if it is a prefix but not equal to the other.
We say that a finite machine
Example
Examples of alphabets:
Capital Greek characters are used to denote alphabets and lowercase Latin characters are used to denote symbols.