20 votes 20 votes Context-free languages are closed under: Union, intersection Union, Kleene closure Intersection, complement Complement, Kleene closure Theory of Computation gate1999 theory-of-computation context-free-language easy + – Kathleen asked Sep 23, 2014 • edited Jul 1, 2017 by Silpa Kathleen 7.5k views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 21 votes 21 votes Context free languages are not closed under intersection and complement. Correct option is (B) Union and Kleene closure. Bhagirathi answered Sep 25, 2014 • edited Jun 15, 2018 by Milicevic3306 Bhagirathi comment Share Follow See all 10 Comments See all 10 10 Comments reply Show 7 previous comments Pascua commented Feb 4, 2021 reply Follow Share No. Consider $L_1 = \{a^nb^n\} \cup \{ca^nb^{2n}\}$. Let $L = \{c\} \cup L_1$. L is DCFL. But L* is CFL 1 votes 1 votes shashankrustagi commented Mar 7, 2021 reply Follow Share This came in TIFR 0 votes 0 votes LiteYagami commented Jan 26 reply Follow Share Let L1 be PALINDROME, defined by: S → aSa | bSb | a | b | Λ • Let L2 be S → aSb | Λ • Then the union language is defined by: S → S1 | S2 0 votes 0 votes Please log in or register to add a comment.
1 votes 1 votes The context-free languages are closed under union, concatenation and Kleene closure. so option B Prasanjeet Ghosh answered Apr 27, 2018 Prasanjeet Ghosh comment Share Follow See all 0 reply Please log in or register to add a comment.
1 votes 1 votes CFLs are not closed under intersection, complement and set difference. Hence, the correct option is (B). ankit3009 answered Jan 13, 2021 ankit3009 comment Share Follow See all 2 Comments See all 2 2 Comments reply shashankrustagi commented Jan 31, 2021 reply Follow Share ankit, is DCFL* is CSL? 0 votes 0 votes ankit3009 commented Jan 31, 2021 i edited by ankit3009 Jan 25, 2022 reply Follow Share DCFL are not closed under Kleene closure, which means it may or may not be DCFL. So, we can't really comment about whether it would bs CSL or not. Hence, not a CSL. Please correct me if I'm wrong. 1 votes 1 votes Please log in or register to add a comment.