# Terminal Symbol Set

A Terminal Symbol Set is a Formal Alphabet (composed of Terminal Symbol) that is associated to a Formal Grammar.

**AKA:**Formal Grammar Terminal Symbol Set,*Σ*,*T*.**Context:**- It can be Disjoint from a Non-Terminal Symbol Set.
- It can be a Member of:

**Example(s):****See:**Non-Terminal Symbol Set.

## References

- http://www.csee.umbc.edu/help/theory/lang_def.shtml
- Alphabet
- A finite set of symbols.
- An alphabet is often denoted by sigma, yet can be given any name.
- B = {0, 1} Says B is an alphabet of two symbols, 0 and 1.
- C = {a, b, c} Says C is an alphabet of three symbols, a, b and c.
- Sometimes space and comma are in an alphabet while other times they are meta symbols used for descriptions.

- Alphabet

### 2007

- (Kakkonen, 2007) ⇒ Tuomo Kakkonen. (2007). “Framework and Resources for Natural Language Evaluation." Academic Dissertation. University of Joensuu.
- Definition 3-1. Symbol, terminal and alphabet.
- A symbol is a distinguishable character, such as “a”, “b” or “c”.
- Any permissible sequence of symbols is called a terminal (also referred to as a word).
- A finite, nonempty set ∑ of terminals is called an alphabet.

- Definition 3-2. String and sets of strings.
- Let Σ be an alphabet.
- A finite sequence of symbols
*S=(x1 x2… xn), n≥0, x∈Σ*is called a*string*in alphabet Σ. - The
*length*|S| of string S is*n*. - The
*empty string*is the sequence of length 0; written ε*.* - Σ* is the set of all strings in Σ.
- In addition, Σ+ = Σ*- {
*ε*}.

- Definition 3-3. Language and sentence.
- Let Σ be an alphabet.
- Any subset [math]L[/math] of Σ* is called a
*language*over alphabet Σ. - Sequence δ = (
*α1 α2 … αn*), where*αi*∈*L*∀*i*, 1≤*i*≤*n*, n' ∈ natural numbers, is called a*sentence*in language*L*.

- Definition 3-1. Symbol, terminal and alphabet.