问题
In the Chomsky classification of formal languages, I need some examples of Non-Linear, Unambiguous and also Non-Deterministic
Context-Free-Language(N-CFL)?
Linear Language: For which Linear grammar is possible( ⊆ CFG) e.g.
L1 = {anbn | n ≥ 0 }Deterministic Context Free Language(D-CFG): For which Deterministic Push-Down-Automata(D-PDA) is possible e.g.
L2 = {anbncm | n ≥ 0, m ≥ 0 }
L2 is unambiguous.
A CF grammar that is not linear is nonlinear.
Lnl = {w: na(w) = nb(w)} is also a Non-Linear CFG.
--
3.
Non-Deterministic Context Free Language(N-CFG): For which only Non-Deterministic Push-Down-Automata(N-PDA)
is possible e.g.
L3 = {wwR | w ∈ {a, b}* }
L3 is also Linear CFG.
--4. Ambiguous CFL: CFL for which only ambiguous CFG is possible
L4 = {anbncm | n ≥ 0, m ≥ 0 } U {anbmcm | n ≥ 0, m ≥ 0 }
L4 is both non-linear and Ambiguous CFG And Every Ambigous CFL \subseteq N-CFL.
My Question is:
Whether all non-linear, Non-Deterministic CFL are Ambiguous? If not then
I need a example that is non-linear, non-deterministic CFL and also unambiguous?
Given Venn-diagram below:
Also asked here
回答1:
"IN CONTEXT OF CHOMSHY CLASSIFICATION OF FORMAL LANGUAGE"
(1) L3 = {wwR | w ∈ {a, b}* }
- Language L3 is a Non-Deterministic Context Free Language, its also Unambiguous and Liner language.
(2) Lp is language of parenthesis matching. There are two terminal symbols "(" and ")".
Grammar for Lp is:
S → SS
S → (S)
S → ()
- This language is nonlinear, deterministic and unambiguous too.
Language L that is union of Lp and L3 is unambiguous, nonlinear (due to Lp), and non-deterministic (due to L3) (Assuming language symbols for both languages are different).
This Language is an example of language in Venn-diagram for which I marked ??
.
Also the correct diagram is below:
An ambiguous context free language also be a liner context free
来源:https://stackoverflow.com/questions/13143186/example-of-non-linear-unambiguous-and-non-deterministic-cfl