User Elimination

4 votes

3 answers

3k views

Show that regular languages are closed under Mix operations

asked May 19, 2015 at 12:25

2 votes

1 answer

2k views

Prove that regular languages and context-free languages aren't closed under $Perm(L)$

formal-languages regular-languages context-free closure-properties

asked May 19, 2015 at 13:01

2 votes

4 answers

2k views

Reduction and decidability

formal-languages turing-machines reductions proof-techniques undecidability

asked May 30, 2015 at 11:05

1 vote

1 answer

163 views

Find a CFG for the language $\{ x\$y \mid x,y\in\{a,b\}^* \wedge |x| \ne |y| \}$?

formal-languages context-free

asked May 2, 2015 at 16:20

1 vote

2 answers

215 views

Prove/ Disprove: If $L$ is a CFL then $A(L)$ is a CFL too

formal-languages context-free closure-properties

asked May 18, 2015 at 14:11

1 vote

1 answer

1k views

Do problems in P only reduce to NP and coNP problems?

complexity-theory reductions np

asked Jun 22, 2015 at 10:01

1 vote

2 answers

148 views

$A$ is finite, $B$ is NPC - When there's a polynomial reduction from $A$ to $B$?

complexity-theory reductions

asked Jun 19, 2015 at 13:25

1 vote

2 answers

268 views

Is an infinite language of halting TM is in $RE$? in $RE \setminus R$?

computability turing-machines

asked Jun 20, 2015 at 10:41

1 vote

1 answer

136 views

Prove/Disprove: $L_1, L_2 \in RE-R \implies L_1 \cup L_2 \notin R$

formal-languages

asked May 23, 2015 at 13:16

0 votes

1 answer

193 views

Proving that a set of grammars for a given finite language is decidable [duplicate]

formal-languages computability context-free

asked Jun 24, 2015 at 17:54

0 votes

1 answer

51 views

Validating authenticity of a file

security

asked Jul 23, 2015 at 9:29

0 votes

0 answers

84 views

Gas Station problem proof

algorithms greedy-algorithms

asked Sep 8, 2021 at 9:20

0 votes

1 answer

540 views

What is the minimal number of states for the DFA?

regular-languages automata finite-automata regular-expressions

asked May 18, 2015 at 17:20

0 votes

1 answer

92 views

Determine if the language is $R$

formal-languages turing-machines reductions undecidability

asked May 31, 2015 at 15:11

-1 votes

1 answer

213 views

union of two equivalence classes (Myhill–Nerode theorem) [closed]

formal-languages regular-languages

asked May 20, 2015 at 15:31

-1 votes

1 answer

372 views

Proving a language isn't regular using the pumping lemma [closed]

formal-languages regular-languages pumping-lemma

asked May 21, 2015 at 12:29

-1 votes

1 answer

531 views

Why is it true that $NP \ne coNP \implies X = \emptyset$?

complexity-theory computability

asked Jun 20, 2015 at 14:22

-2 votes

1 answer

62 views

Prove/ Disprove: For every nontrivial $A,B \in R (RE)$, $A\le_m B$ [closed]

computability

asked Jun 13, 2015 at 17:14

-2 votes

1 answer

88 views

What is the minimal states for the language DFA?

formal-languages regular-languages

asked May 19, 2015 at 18:18

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19 Questions

Show that regular languages are closed under Mix operations

Prove that regular languages and context-free languages aren't closed under $Perm(L)$

Reduction and decidability

Find a CFG for the language $\{ x\$y \mid x,y\in\{a,b\}^* \wedge |x| \ne |y| \}$?

Prove/ Disprove: If $L$ is a CFL then $A(L)$ is a CFL too

Do problems in P only reduce to NP and coNP problems?

$A$ is finite, $B$ is NPC - When there's a polynomial reduction from $A$ to $B$?

Is an infinite language of halting TM is in $RE$? in $RE \setminus R$?

Prove/Disprove: $L_1, L_2 \in RE-R \implies L_1 \cup L_2 \notin R$

Proving that a set of grammars for a given finite language is decidable [duplicate]

Validating authenticity of a file

Gas Station problem proof

What is the minimal number of states for the DFA?

Determine if the language is $R$

union of two equivalence classes (Myhill–Nerode theorem) [closed]

Proving a language isn't regular using the pumping lemma [closed]

Why is it true that $NP \ne coNP \implies X = \emptyset$?

Prove/ Disprove: For every nontrivial $A,B \in R (RE)$, $A\le_m B$ [closed]

What is the minimal states for the language DFA?