prefix
Substring obtained by removing zero or more symbols from the tail of s
suffix
the substring obtained by removing zero or more zero symbols from the head of s
substring
Substring obtained by removing a prefix and a suffix from s
True Prefixes, True Suffixes, and True Substrings
not prefixes, suffixes and substrings of s and ε
subsequence
remove zero or more symbols from s (not required to be consecutive)
reverse
the string of symbols obtained by writing the symbols in s in reverse order
length
the number of symbols in the symbol string
language
Determines the set of strings on the character table. The set of all strings on the character table is the largest, denoted as ∑ *
grammar
A grammar G is a quadruple (V T ,V N ,S,P)
where:
1. V T is a set of non-empty finite terminals
2. V N is a set of non-empty finite non-terminals, And V T ∩V N = Φ
3. S∈V N starts the symbol.
4. P is a non-empty finite set of productions, each production is A→α, where A∈V N ,α∈(V T ∪V N ) * start symbol S must be at least on the left side of a production Department appears once.
finite state automata
A deterministic finite automatic state machine DFA is a quintuple, D = (K , ∑ , M , S , T), where:
K: state set
∑: alphabet
M: K * ∑ → K mapping
S: start state, S∈K
T: end state set, T⊆K
Uncertain Finite State Automata
An indeterminate finite automatic state machine UFA is a quintuple (K , ∑ , M , S , T ), where:
K: set of states
∑: set of subsets of alphabet
M: K * ∑ → K
S: start state set, S⊆K
T: end state set, T⊆K