Linked Questions

4
votes
3answers
5k views

Irregularity of $\{a^ib^jc^k \mid \text{if } i=1 \text{ then } j=k \}$

I read on the site on how to use the pumping lemma but still I don't what is wrong with way I'm using it for proving that the following language is not a regular language: $L = \{a^ib^jc^k \mid \text{...
2
votes
1answer
85 views

How to choose a word to apply the Pumping Lemma?

I have some questions about the PUMPING LEMMA. First of all, I do not study computer science, I still go to school, but I'm very interested, so I could make mistakes. And sorry about my English :) ...
0
votes
0answers
26 views

Using Nerode theorem to prove that the following languages are non-regular

I've been trying to understand the idea behind proving a language is not regular by using Nerode's theorem, but I just couldn't apply the idea on what I've been asked. The problem is to prove the ...
1
vote
2answers
75 views

Prove that a language is not regular with process of elimination [duplicate]

When deterministic automaton, I need to prove that you can't implement the language in it, because the language is not regular. Easiest way to prove that a language is regular, is just by making an ...
3
votes
1answer
91 views

Is the language of words with equal number of 010s and 101s as substrings regular?

Is the language of words containing same number of 101s and 010s regular? If yes, how can I design a DFA for it? In general, is the language of words containing equal number of strings which one is "...
0
votes
1answer
56 views

DFA for $L = \{y \in (a+b)^* \mid ||y|_a - |y|_b| \leq 10 \}$

$L = \{y \in (a+b)^* \mid ||y|_a - |y|_b| \leq 10 \}$ Any idea? I have problem with this kind of task.
1
vote
1answer
76 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: $$ L = \{ a^n b^n \mid n \ge 0\} $$ ...
0
votes
0answers
74 views

Show that the language L = {www : w ∈ {0, 1} ∗} is not regular [duplicate]

Hey was wondering if I'm applying the pumping lemma correctly for this proof or if this proof could be improved? Suppose $L = \{www:w\in\{0,1\}^*\}$ is a regular language. Let $p$ be the number from ...
-2
votes
1answer
52 views

Provide “regular” grammar for this language {${a^ib^j \mid i>0\ and \hspace{2.5mm}i\leq j \leq(2*i)}$} [duplicate]

I'm trying to understand the approach to constructing an grammar which accepts the language ${a^ib^j \mid i>0\ and \hspace{2.5mm}i\leq j \leq(2*i)}$ } Thanks.
1
vote
1answer
48 views

Why is this not recognized by a DFA?

I am still confused over my professor's explanation on why this problem is not a DFA. The Problem: Explain why $L = \{p^kq^k \mid k>0\}$ cannot be recognized by a DFA My professor explained it as ...
2
votes
0answers
53 views
1
vote
1answer
60 views

How to show that the language made up of strings with nlogn 0s is not regular with the pumping lemma?

How to show that the following language is not regular with the pumping lemma? $$L=\left\{0^{n\lceil\log_2 n\rceil} \,\middle|\, n\in \mathbb{N}-\{0\}\right\}.$$
-1
votes
1answer
55 views

Proving a language is non-regular using the Pumping Lemma for non-binary strings [duplicate]

I am unsure of how to prove this language is non-regular. I do not even know where to start to develop a string that would prove the language is non-regular by contradiction. Any help would be ...
7
votes
1answer
808 views

What's wrong with my pumping lemma proof?

The language $L = \{0^{2n} \space |\space n \ge 0 \}$ is obviously regular – for example, it matches the regular expression $(00)^*$. But the following pumping lemma argument seems to show it's ...
0
votes
0answers
17 views

Regular grammar question [duplicate]

Define a regular expression such that there is a string of 1 or more a's continuous followed by a continuous string of b's so that the number of a's and b's are the same. I have ideas on how i would ...

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