Languages
Languages
In TOA, language is any set of strings over an alphabet of symbols. Like the english language which have rules known as Grammar, this language will also conform to some rules that we will define, and only the strings that follow these rules will be a part of our defined language.
Alphabet
An Alphabet is a finite set of symbols, such as {a, b} or {0, 1} or {0, 1, 2, 4} or {A, B, E, G}. Alphabet is represented by $\Sigma$.
Length
For a string x, |x| is length of that string
Kleene Star
For a given alphabet $\Sigma$ , the set containing all possible strings including the empty string that can be generated from that alphabet is called Kleene Star denoted by $\Sigma$*.