User Mike B.

19 votes

Intersection and union of a regular and a non-regular language

answered Jun 28, 2012 at 20:46

13 votes

Accepted

Are Turing machines more powerful than pushdown automata?

answered Mar 22, 2012 at 20:02

8 votes

Accepted

Is it $\mathsf{NP}$-hard to decide whether $\mathsf{P}=\mathsf{NP}$?

answered Jan 4, 2013 at 12:26

7 votes

Accepted

PSPACE and NP complexity

answered Dec 6, 2013 at 12:24

6 votes

Does NP=coNP imply P=NP?

answered Dec 30, 2013 at 22:18

6 votes

Proving NP is a subset of the union of exponential DTIME

answered May 29, 2012 at 9:47

5 votes

5-state DFA that recognizes only the string 00001111

answered Apr 19, 2017 at 7:37

5 votes

Accepted

If P != NP, then 3-SAT is not in P

answered Jun 10, 2014 at 11:36

4 votes

Accepted

Proving that the language of satifiable CNF formulae with primes is NP-complete

answered Feb 2, 2016 at 10:27

4 votes

5-state DFA that recognizes only the string 00001111

answered Apr 20, 2017 at 9:31

4 votes

Accepted

Kleene star Empty language

answered Mar 7, 2017 at 18:57

3 votes

co-NP but not NP problems

answered Mar 6, 2017 at 9:30

3 votes

Can every single regular expression be translated into deterministic finite automata?

answered Dec 13, 2016 at 6:33

3 votes

How do I show that a DFA accepts only one word?

answered Feb 27, 2015 at 15:05

2 votes

Is a PDA as powerful as a CPU?

answered May 16, 2012 at 12:59

2 votes

Accepted

Is regular expression syntax regular?

answered Jun 23, 2017 at 9:01

2 votes

Accepted

Is this possible to solve 4SAT in polynomial time?

answered Jul 18, 2017 at 9:58

1 vote

Working out the connectives (And, Or, Not) in a Truth Table that has the outputs

answered Nov 10, 2014 at 14:30

1 vote

Convert regular expression to Automaton

answered May 15, 2014 at 14:28

1 vote

Does complement distribute over concatenation?

answered Mar 11, 2015 at 14:10

1 vote

Is badly written code derogatory to the compiler?

answered Jul 13, 2015 at 14:01

1 vote

Where is the ambiguity in this grammar?

answered Oct 8, 2015 at 9:17

1 vote

Is the complement of the given language necessarily in NP?

answered Feb 2, 2016 at 13:36

0 votes

Is $(a+b)^*$ closed under reversal?

answered Feb 15, 2017 at 8:51

0 votes

Accepted

How to write Context-free Grammar for this language?

answered Dec 3, 2015 at 14:11

0 votes

Is $L=\left \{ wxw \,\,|\,\,w,x \,\in \left ( a+b \right )^{+}\right \}$ Regular?

answered Oct 6, 2017 at 12:52

-1 votes

How to reduce this regular expression into DFA

answered Mar 2, 2017 at 6:58

Stack Exchange Network

27 Answers

Intersection and union of a regular and a non-regular language

Are Turing machines more powerful than pushdown automata?

Is it $\mathsf{NP}$-hard to decide whether $\mathsf{P}=\mathsf{NP}$?

PSPACE and NP complexity

Does NP=coNP imply P=NP?

Proving NP is a subset of the union of exponential DTIME

5-state DFA that recognizes only the string 00001111

If P != NP, then 3-SAT is not in P

Proving that the language of satifiable CNF formulae with primes is NP-complete

5-state DFA that recognizes only the string 00001111

Kleene star Empty language

co-NP but not NP problems

Can every single regular expression be translated into deterministic finite automata?

How do I show that a DFA accepts only one word?

Is a PDA as powerful as a CPU?

Is regular expression syntax regular?

Is this possible to solve 4SAT in polynomial time?

Working out the connectives (And, Or, Not) in a Truth Table that has the outputs

Convert regular expression to Automaton

Does complement distribute over concatenation?

Is badly written code derogatory to the compiler?

Where is the ambiguity in this grammar?

Is the complement of the given language necessarily in NP?

Is $(a+b)^*$ closed under reversal?

How to write Context-free Grammar for this language?

Is $L=\left \{ wxw \,\,|\,\,w,x \,\in \left ( a+b \right )^{+}\right \}$ Regular?

How to reduce this regular expression into DFA