23 votes 23 votes Context-free languages are: closed under union closed under complementation closed under intersection closed under Kleene closure Theory of Computation gate1992 context-free-language theory-of-computation normal multiple-selects + – Kathleen asked Sep 13, 2014 • edited Apr 19, 2021 by Lakshman Bhaiya Kathleen 4.9k views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 27 votes 27 votes Answer: A;D. Context-Free languages are not closed under intersection and complementation. Rajarshi Sarkar answered Apr 25, 2015 • edited Apr 19, 2021 by Lakshman Bhaiya Rajarshi Sarkar comment Share Follow See all 4 Comments See all 4 4 Comments reply Rohan Mundhey commented May 9, 2016 reply Follow Share CFG are closed under Union , Kleen closure & Concatenation . Also CFG are closed under Regular intersection BUT , are CFG closed under Regular Union ? I think yes...coz..every regular is CFG & CFG are closed under union .... correct me if I am wrong 1 votes 1 votes Shashi Shekhar 1 commented Aug 30, 2018 reply Follow Share So take two regular language sigma* over {a,b} and other as {a}then their union is sigma* ,which is not cf. Correct me if I am wrong. 0 votes 0 votes air1ankit commented Oct 26, 2018 reply Follow Share https://gateoverflow.in/?qa=blob&qa_blobid=8929616163903734815 0 votes 0 votes JAINchiNMay commented Nov 23, 2022 reply Follow Share @air1ankit I have some doubt in the above table 1. DCFL closed under reversal? CSL closed under set difference? REC under epsilon free substitution? for 1. formal languages - Are DCFLs closed under reversal? - Computer Science Stack Exchange 0 votes 0 votes Please log in or register to add a comment.
4 votes 4 votes According to the above table we can say , A and D is correct answer air1ankit answered Dec 12, 2017 air1ankit comment Share Follow See all 3 Comments See all 3 3 Comments reply Puja Mishra commented Jan 12, 2018 reply Follow Share wat is GSM mapping ?? 0 votes 0 votes Lakshman Bhaiya commented Jan 21, 2018 reply Follow Share Gsm mapping Short for generalized sequential machine mapping. A function that is the response function of a generalized sequential machine, and therefore generalizes the notion of sequential function. Without constraining the machine to have a finite state-set, generalized sequentiality is equivalent to the following property of initial subwords preservation: for all u,v in I*, f(uv) has the form f(u)w for some w in O*, where I* and O* are the sets of all input and output strings. 2 votes 2 votes ramcharantej_24 commented Nov 28, 2020 reply Follow Share What is Substitution Operation? 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes A is right D is right because $(CFL)^* = Regular$ all regular are CFL’s shashankrustagi answered Dec 1, 2020 shashankrustagi comment Share Follow See 1 comment See all 1 1 comment reply sameer_hack commented Jan 31, 2023 reply Follow Share From where did you get that $(CFL)^*$ = Regular? 0 votes 0 votes Please log in or register to add a comment.
0 votes 0 votes A & D CFL’s are NOT CLOSED under INTERSECTION, COMPLEMENTATION, DIFFERENCE. DCFS’s are NOT CLOSED under INTERSECTION, UNION, CONCATENATION, KLEENE CLOSURE, DIFFERENCE, REVERSAL, HOMOMORPHISM. manikantsharma answered Aug 27, 2022 manikantsharma comment Share Follow See all 0 reply Please log in or register to add a comment.