Linked Questions

3
votes
1answer
178 views

How to prove for that a given non-regular language its given super-set is also non-regular? [duplicate]

Consider the non-regular language $L_1$ = {$a^n$b$a^n$: $n \geq 0$} and its super-set language L = Language of strings with equal number of trailing and leading a's, or in other words, $$L = \{a^...
2
votes
2answers
104 views

Class of a Language [duplicate]

What are the common ways to check if a given language is regular, context free, or context sensitive? Any surveys or notes would also be helpful. There's no need to describe your suggestions. eg. it ...
-1
votes
1answer
445 views

Proving a grammar/language as not regular [duplicate]

$D → T ∨ D | T$ $T → C ∧ T | C$ $C → ¬C | name | ( D )$ $name → a | b | c | d$ I am not looking for the complete answer, but more the methodology of working this out. How would I go about proving ...
1
vote
1answer
331 views

Show this language is non-regular using pumping lemma: B = {ww | w ∈ {a,b,c,…,z)*} [duplicate]

The question I'm working from is: Prove whether or not a finite automation exists that recognises the following language: B = {ww | w ∈ {a,b,c,...,z)*} EDIT So I believe this is a non-regular ...
1
vote
1answer
339 views

proving {$a^ib^jc^k : j = i \lor j = k$} is not regular [duplicate]

i had troubles proving this is not regular using the pumping lemma {$a^ib^jc^k : j = i \lor j = k$}. Not sure how to approach this anymore, and help would be appreciated
1
vote
1answer
150 views

Proving a language is not a regular language but a context free language [duplicate]

I have the languages $L_1$ and $L_2$ such that $L_1 = \{a^nba^n :n \in N\}$ and $L_2 =\{a,b\}^*\setminus L_1$. I want to prove that $L_2$ is not a regular language. I know that to prove that $L_2$ is ...
1
vote
3answers
301 views

Irregularity of language of words whose length is of power of 2 [duplicate]

How to show that the language containing the words whose length is a power of $2$, $L=\{w\mid|w|=2^i\}$, isn't regular using the pumping lemma? The pumping lemma says that Let be M a regular ...
2
votes
2answers
106 views

Prove that the following language is not regular: $\{0^i1^j : i \neq j\}$ [duplicate]

I was trying to approach this proof, after multiple reads and attempts I am getting nowhere. If someone could help me out that would be great. Should I use the pumping lemma, if so how show I start, ...
0
votes
1answer
116 views

Showing that $\{ c^n a^m b^{n+m} : n+m \geq 6\}$ is not regular [duplicate]

I'm trying to show that $L_6=\{c^n a^m b^p : n+m=p,p \geq 6\}$ is not regular. I need a little help, I was practicing the pumping lemma, and I encountered this language, I saw these conditions and got ...
0
votes
1answer
106 views

Prove this language is non-regular [duplicate]

I'm struggling to understand this question using pumping lemma to prove a language is not regular. Any help would be appreciated. Prove using the Pumping Lemma that the following language is not ...
0
votes
2answers
129 views

How to prove that these two languages are regular, or not regular? [duplicate]

I have these two languages $L_1={\{a^n b^m,n≥m+5,m>0}\}$ Where $∑=(a,b)$ $L_2={\{a^n b^m,n≥m+5,m≤5}\}$ Where $∑=(a,b)$ As you can see that there is only one difference, the condition of ...
0
votes
1answer
144 views

Why are these languages not regular? [duplicate]

Show that the following languages are not regular: $(1)\ L=\left\{a^nb^mc^k\mid n>k \land n,m,k>0\right\}$ $(2)\ L=\left\{a^nb^mc^k\mid m>k \land n,m,k>0\right\}$ I've difficulties ...
1
vote
1answer
170 views

Pumping Lemma vs Myhill-Nerode [duplicate]

I was searching for a difference on both ways of proving that a language is not regular but I didn't came up with much. Let us take the following as an example: $$ L = \{ a^n b^n \mid n \ge 0\} $$ ...
2
votes
1answer
102 views

How to prove that $L_1=1^*\cup \{0^i 1^{j^2}|i\ge 0,j\ge 0\} $ is irregular? [duplicate]

We know that $L=\{0^i 1^{j^2}|i> 0,j\ge 0\} $ is irregular (by the Pumping Lemma), we have to use it to prove two things: $L_1=1^*\cup \{0^i 1^{j^2}|i\ge 0,j\ge 0\} $ is irregular. $L_1$ is ...
1
vote
1answer
141 views

How to show that $L=\{ wa^kw | w \in \{ a,b,c \}^* ,k \geq 0 \}$ is not regular using the pumping lemma for regular languages? [duplicate]

I'm trying to show that the language in the title is not regular but I don't know how to chose a decomposition $x = abc$ to express the word in the language because the $w \in \{a,b,c\}^*$ is kinda ...

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