18 Are context-free languages in $a^*b^*$ closed under complement? 2013-04-07T19:05:16.153

15 Proving closure under reversal of languages accepted by min-heap automata 2012-03-14T20:17:55.613

14 Are the Before and After sets for context-free grammars always context-free? 2012-03-26T17:48:12.210

11 Closure against right quotient with a fixed language 2012-04-28T10:33:42.823

11 Operations under which the class of undecidable languages isn't closed 2012-04-28T11:50:33.113

11 Prove that the complement of $\{0^n1^n \mid n \geq{} 0\}$ is not regular using closure properties 2012-09-26T20:53:42.597

11 Union of regular languages that is not regular 2014-10-01T01:12:36.097

10 Is an inﬁnite union of context-free languages always context-free? 2012-03-10T18:10:35.290

10 How to prove regular languages are closed under left quotient? 2012-04-17T20:58:50.560

10 Easy proof for context-free languages being closed under cyclic shift 2013-01-08T12:59:17.587

10 Constructing all context-free languages from a set of base languages and closure properties? 2014-09-15T16:04:57.243

9 What is complement of Context-free languages? 2012-12-04T01:48:38.370

8 Proving closure under complementation of languages accepted by min-heap automata 2012-03-14T21:51:34.593

8 Proving the language which consists of all strings in some language is the same length as some string in another language is regular 2012-11-05T05:52:51.367

8 Is $A$ regular if $A^{2}$ is regular? 2013-02-16T07:41:52.540

8 Is there a strictly non-deterministic one-counter language whose complement is one-counter? 2013-03-19T15:44:35.443

8 Regularity of the exact middle of words from a regular language 2013-04-04T15:05:08.010

8 Demonstrate that DPDA is closed under complement by construction 2013-12-10T00:34:01.010

8 If $L_1L_2$ is regular language then $L_2L_1$ is regular to? 2015-12-04T16:21:21.193

7 Is #P closed under exponentiation? modulo? 2012-08-12T12:30:28.490

7 Context-free Languages closed under Reversal 2012-11-28T12:31:08.280

7 Myhill-Nerode and closure properties 2012-12-16T17:09:42.133

7 How to prove that context sensitive languages are closed under intersection and complement? 2013-10-12T11:14:06.500

7 how to draw a complement of a Turing Machine? 2014-04-02T23:50:40.633

7 are NP Complete languages closed under any regular operations? 2014-04-30T16:34:39.267

7 Are DCFLs closed under reversal? 2014-10-07T13:05:04.923

7 How to XOR automata? 2014-11-12T08:58:44.107

7 Is the closure of P under e-free homomorphisms equal to NP? 2015-05-26T23:02:52.393

7 Smallest class of automata model whose corresponding language class contains CFL and is closed against (dis)allowing nondeterminism in the model 2015-06-01T19:59:19.180

7 Context-free languages not closed under making them "extension-free" 2015-11-18T08:29:40.320

6 If $L$ is context-free and $R$ is regular, then $L / R$ is context-free? 2012-05-17T16:19:42.050

6 Prove that regular languages are closed under the cycle operator 2012-05-22T05:28:58.017

6 What does it mean to say that a language is "effectively closed" under an operation? 2013-05-09T19:51:28.577

6 Kleene star of an infinite unary language always yields a regular language 2014-02-18T14:05:22.823

6 Is the class NP closed under complement? 2014-04-30T16:23:40.070

6 If L is context-free, must FH(L) be context-free? 2014-11-03T01:08:23.457

6 Are the complements of $NP$-languages with only $n$ words of length $n$ also in $NP$? 2014-11-05T07:37:40.243

6 Closure properties of linear context-free languages 2015-05-12T18:46:38.600

6 Why do we study closure properties of formal languages? 2016-04-13T05:32:50.920

6 Should two DFAs be complete before making an intersection of them? 2016-10-24T08:25:51.310

5 Closure against the operator $A(L)=\{ww^Rw \mid w \in L \wedge |w| \lt 2007\}$ 2012-04-27T18:59:52.513

5 The operator $A(L)= \{w \mid ww \in L\}$ 2012-05-03T11:55:44.033

5 Closure of Deterministic context-free languages under prefix 2012-01-15T21:51:40.653

5 Deterministic context-free languages are closed under regular right-product 2012-11-30T10:53:41.263

5 Proof that regular languages are closed against taking the even-length subset 2013-03-30T22:49:33.747

5 Why isn't the class of Turing-Recognizable languages closed under Complement? 2013-04-07T17:52:07.083

5 Closure under intersection of context free binary trees 2013-04-07T21:12:07.577

5 Prove that $L_1$ is regular if $L_2$, $L_1L_2$, $L_2L_1$ are regular 2013-04-27T03:06:35.000

5 Reference request: proof that if $L \in DCFL$, then $L \Sigma^* \in DCFL$ 2013-07-09T17:23:08.623

5 Prove that context free languages aren't closed under DropMiddle 2014-03-21T15:33:06.103

5 Intersection of two NPDAs 2014-03-26T02:34:19.813

5 Difference between substitution, morphism, and homomorphism 2015-04-07T23:29:30.240

5 Question on NP $\cap$ coNP 2015-05-18T13:06:31.340

5 Are deterministic and nondeterministic Cellular Automata equivalent? 2015-06-06T07:18:17.170

5 Is an irregular language concatenated with a language with which it has no common symbols irregular? 2015-09-15T01:43:48.757

4 Proving that recursively enumerable languages are closed against taking prefixes 2012-05-08T15:36:31.447

4 Does closure against countable union survive union of classes? 2013-03-20T14:20:03.700

4 Why NP is not closed under Turing reduction 2013-06-08T09:08:33.743

4 $\mathbf{NC}$ is closed under logspace reductions 2013-07-22T12:55:57.660

4 Decidable languages kleene star closure - question on a proof 2014-01-18T18:43:45.827

4 Is there $L$ such that $L$ and $\bar L$ are context free, but $L$ is not deterministic context free? 2015-01-20T10:41:32.943

4 If $L$ is a regular language then so is $\sqrt{L}=\{w:ww\in L\}$ 2015-04-12T03:47:56.850

4 Proof that CFL aren't closed under intersection using synchronous parallel (N)PDA composition 2015-06-17T20:26:24.703

4 Closure properties of the class of inherently ambiguous CFLs 2016-04-01T15:51:06.410

4 Is NEXP = co-NEXP? 2016-05-05T07:38:23.913

4 Proving that PP is closed under symmetric difference 2016-06-20T12:50:03.133

4 Prove that PP is closed under complement 2016-08-16T13:36:53.870

4 Inverse Homomorphisms and Kleene star 2016-12-13T23:09:32.817

4 Closure of regular languages to shuffle using closure operations 2017-01-08T19:27:16.297

4 For a regular language $L$, is $\{xy^Rz:xyz\in L\}$ regular? 2017-04-27T12:16:30.310

4 Closure operator and set of fixpoint 2017-09-14T20:01:20.173

4 How to prove that a transformed language is regular using an NFA 2018-02-12T23:14:21.620

4 Complement of Mealy machine 2018-03-01T14:36:53.140

4 Can the regular image of a context-free language be undecidable? 2018-03-08T21:44:11.350

3 If $L$ is a regular language, how to prove $L_1 = \{ uv \mid u \in L, |v| =2 \}$ is also regular? 2012-10-24T05:09:01.860

3 "Definition of NP via relations and quantifiers; not via NTMs" 2013-02-14T23:48:53.697

3 Can we say anything about the complement of a regular language? 2013-03-11T14:18:52.303

3 Are permutations of context-free languages context-free? 2013-04-15T12:09:49.237

3 Complement of Non deterministic Finite Automata 2013-07-15T10:40:24.740

3 Is $\{s_0 w s_1 : s_0s_1\in L_1, w\in L_2 \}$ context free if $L_1$ and $L_2$ are? 2013-10-13T18:47:16.867

3 Prove the existence of regular $C$ so that: $A \prec C \prec B $ 2013-12-05T15:55:23.273

3 If $L$ is CFL and $\overline{L}$ is CFL, then is L regular? 2014-01-19T20:00:18.470

3 Kleene star closure of a context free grammar 2014-01-24T23:59:34.787

3 Why is the class of recursively enumerable languages not closed under complementation? 2014-02-04T11:23:23.813

3 Do Kleene star and complement commute? 2014-02-11T23:09:29.767

3 Situations where Kleene star of A is context-free, but A is not 2014-05-16T01:49:22.730

3 Generators of families of langauges? 2014-06-02T23:04:54.047

3 Clearing a Confusion regarding the Proof of equal no of a's and b's not being a regular language 2014-09-13T13:28:19.890

3 If both the concatenation of two languages and the second "half" are regular, is the first too? 2014-10-09T17:30:16.897

3 Proving regular languages are closed under a form of interleaving 2015-05-09T13:22:44.293

3 Show that regular languages are closed under Mix operations 2015-05-19T12:25:04.447

3 Symmetric Difference of Turing Recognizable and Finite Languages 2015-07-01T19:31:17.973

3 How to prove closure property of regular languages using regular expressions? 2015-10-19T08:45:01.477

3 L closed under logspace reduction 2016-02-03T11:23:41.727

3 Why are palindrome and not-palindrome both context-free? 2016-04-01T13:55:10.710

3 Why DCFL is not closed under kleene star? 2016-06-04T15:46:22.550

3 How to Trace Path in Proof that Regular Languages are Closed Under Reversal 2016-06-13T03:27:05.860

3 Showing Regular Languages are closed under removal of rightmost character 2016-08-04T22:31:33.710

3 Show that NP is closed under concatenation 2016-11-30T18:58:21.517