2 votes 2 votes Context free languages are closed under union, intersection union, kleene closure intersection, complement complement, kleene closure Theory of Computation isro-2020 theory-of-computation context-free-language easy + – Satbir asked Jan 13, 2020 edited Apr 10, 2020 by go_editor Satbir 2.7k views answer comment Share Follow See 1 comment See all 1 1 comment reply HiteshVaish commented Jul 7, 2020 reply Follow Share CFLs are closed under kleene closure and union therefore option B is correct 0 votes 0 votes Please log in or register to add a comment.
3 votes 3 votes Context Free Languages are: 1) Closed under Union, Kleen Closure 2) not closed under intersection and complementation. However, Deterministic CFL are closed under intersection, but not closed under Union. b) union, kleen closure is the answer. zdfgdfgas answered Jan 25, 2020 zdfgdfgas comment Share Follow See all 0 reply Please log in or register to add a comment.
1 votes 1 votes $\underline{\textbf{Answer:}\Rightarrow}\;\mathbf{b.}$ Context-free languages are closed under Union and Kleene Closure but not closed under intersection. `JEET answered Jan 13, 2020 `JEET comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes Lemma: The context-free languages are closed under union, concatenation and Kleene closure. That is, if $L_{1}$ and $L_{2}$ are context-free languages, so are$L_{1}$U$L_{2}$, $L_{1}$.$L_{2}$and $L_{1}*$ Proof: We will prove that the languages are closed by creating the appropriate grammars. Suppose we have two context-free languages, represented by grammars with start symbols $S_{1}$and $S_{2}$ respectively. First of all, rename all the terminal symbols in the second grammar so that they don't conflict with those in the first. Then: To get the union, add the rule To get the concatenation, add the rule To get the Kleene Closure of , add the rule to the grammar for . So B is correct. Ref: http://www.cs.nuim.ie/~jpower/Courses/Previous/parsing/node43.html smsubham answered Mar 20, 2020 smsubham comment Share Follow See all 0 reply Please log in or register to add a comment.
0 votes 0 votes Option B) CFL’s are closed under union and kleene closure. Sanandan answered Oct 3, 2020 Sanandan comment Share Follow See all 0 reply Please log in or register to add a comment.