Alphabet (formal languages)
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Contents
Definition
The "alphabet" of a string, grammar, DFA and so forth, typically denoted [ilmath]\Sigma[/ilmath] (capital "sigma") is a finite set of "symbols" used in the sentences or strings under discussion
- It may not be emptyWarning:[Note 1]
See also
- Strings - finite tuples of symbols from an alphabet.
- Star-closure - for example [ilmath]\Sigma^\ast[/ilmath]
- Positive-closure - for example [ilmath]\Sigma^+[/ilmath]
- Grammar
- DFA
- NFA
Notes
- ↑ Significant work must be done to alter later definitions to deal with the possibility of an empty alphabet, so it is easier not to
References
