Let $\LL$ be a formal language.
An alphabet consists of the following parts:
Depending on the specific nature of any particular formal language, these too may be subcategorized.
Common examples of signs are parentheses, "(" and ")", and the comma, ",".
The logical connectives are also signs.
The symbols which comprise $\AA$ are called the primitive symbols of $\AA$.
Hence the distinction between these newly-introduced symbols and the primitive symbols.
Also denoted as
Some sources use $\Sigma$ to denote an arbitrary alphabet.
- 1979: John E. Hopcroft and Jeffrey D. Ullman: Introduction to Automata Theory, Languages, and Computation ... (previous) ... (next): Chapter $1$: Preliminaries: $1.1$ Strings, Alphabets and Languages
- 1988: Dominic Welsh: Codes and Cryptography ... (previous) ... (next): Notation: Alphabets and strings
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): alphabet
|This page may be the result of a refactoring operation.|
As such, the following source works, along with any process flow, will need to be reviewed.
When this has been completed, the citation of that source work (if it is appropriate that it stay on this page) is to be placed above this message, into the usual chronological ordering.
In particular: Check what the actual definitions in these sources actually say
If you have access to any of these works, then you are invited to review this list, and make any necessary corrections.
To discuss this page in more detail, feel free to use the talk page.
When this work has been completed, you may remove this instance of