If the set of all strings of composite length is a regular language, you can use that to prove the set of all strings of prime length are also a regular language.

But it’s also easy to prove that the set of language of strings of prime length is not regular, and thus the language of strings of composite length also can’t be regular.

A more formal proof.

You got downvoted here but you’re absolutely right. It’s easy to prove that the set of strings with prime length is not a regular language using the pumping lemma for regular languages. And in typical StackExchange fashion, someone’s already done it.

Here’s their proof.

Claim 1: The language consisting of the character 1 repeated a prime number of times is not regular.

A further argument to justify your claim—

Claim 2: If the language described in Claim 1 is not regular, then the language consisting of the character 1 repeated a composite number of times is not regular.

Proof: Suppose the language described in Claim 2 is regular if the language described in Claim 1 is not. Then there must exist a finite-state automaton A that recognises it. If we create a new finite-state automaton B which (1) checks whether the string has length 1 and rejects it, and (2) then passes the string to automaton A and rejects when automaton A accepts and accepts when automaton A rejects, then we can see that automaton B accepts the set of all strings of non-composite length that are not of length 1, i.e. the set of all strings of prime length. But since the language consisting of all strings of prime length is non-regular, there cannot exist such an automaton. Therefore, the assumption that the language described in Claim 2 being regular is false.

Average Matt Parker code

“at least 2 characters repeated [at least] twice” implies the string’s length is divisible by a number greater than 1.

Yeah but it’s just so tempting… It validates so many inputs so easily…

They said—

A line with exactly 0 or 1 characters, or a line with a sequence of 1 or 3 or more characters, repeated at least twice

Note—

…or a line with a sequence of 1 or 3 or more characters, repeated at least twice

It should be—

…or a line with a sequence of 2 or more characters, repeated at least twice

The regex in the post will match “abab”. Their original description (line 2 of this comment) will not match “abab”.

It’s a line with a sequence of two or more characters repeated at least twice.

What is Hygge?

Yes, they’re similar, but from what I’ve heard, most UK building societies are basically the same as or worse than banks in terms of fees, rates, and service quality. In the US, most credit unions will absolutely spank the big banks on at least two of those, if not all three.

Oops, I didn’t see that. My bad. Guess I made a fool of myself here.

deleted by creator

I will start. I’m in the United States.

Credit unions! Nearly half of all Americans are credit union members. They don’t seem to be popular in Europe and Asia. A credit union is a not-for-profit co-operative financial institution that essentially provides all the same services as a bank, except it’s run as a democratic institution with directors elected by the customers instead of as a profit maximisation machine for shareholders.

Okay bud. Have a biscuit 🍪

“first and only Kanji”.

If English had other logograms, I 🤔 what they’d be?

Surely you have a bit more thinking power than that. If you gave each of your bullet points a mere five seconds each of critical thought, you wouldn’t have made this ridiculous comment.

Those countries you mentioned? Of course there are people living in them. But there aren’t as many English-speakers as in America. I didn’t say all, I say most (this will be a recurring theme).

With the exception of southern Africa (76%), the rest of Africa has Internet penetration rates below 50%. As low as 27% in east Africa. Remember, I didn’t say all, I said most.

China’s great firewall prevents most people from accessing the outside Internet, and many Chinese people don’t care to. I know this, because I’m fucking Chinese. Is it possible to circumvent? Sure, if you’re willing to play VPN whack-a-mole with the CCP or are lucky enough to be the 1% of China that lives in Hong Kong or Macau. But again, I said most, I didn’t say all.

You also clearly have never been on any forums populated by Indian users if you think that I’m only saying Indians use unintelligible English on the Internet because I’m racist. They code-switch between English and Hindi. If you don’t know Hindi, you won’t understand it. Are all posts like this? Of course not. But a great deal are. I never said all, I said most.

Here are random top comments from the top posts of Reddit’s r/Indiasocial that show what I’m talking about:

Kal bolne ja rha Hu usko . Want to get it over it once and for all been bugging me since some time . No boldiya toh sahi hai Padhai kar lunga .

Kassh bta pata mummy ko apni sab problems. Bta bii nhi pata kyuki woh chinta karengii

OP ke AAnde jalwa diye

Folks, look what I found during cleaning today😭🥺🥹

I am so happy that my mom has still kept all of stuff in the store room. Woh bhi kya din the🥹🥹

Bhai hamare side ke Ghar mein kirayedar rehte Hain. To un baccho kii ball hamari chat ya backyard mein aa jati thi aur mere ek Purina badi wali thaili bharke balls bahut variety Hain par mummy nikalne NAHI deti.

Time to leave this sub. Har dusara post my gf/bf made this, i went for date, gift given by my bf/gf. Had hai

And also, I don’t use American English. I live in America but I am a Hongkonger and use British English.

But…

The AI is the artist!

Not sure what this other guy is doing though.

The average American uses only English language forums.

The average European who speaks English will probably spend some portion of their time using whatever their native language is.

The average English speaker in Africa is not as likely to have an Internet connection.

The average English speaker in China is likely to not be able to access English social media sites (great firewall).

Many English-speakers in India post online in a mix of English and Hindi that non-Indians find difficult to comprehend.

You’re correct that the claim that the US is ¾ the population of Europe is erroneous. But it is ¾ the population of the EU. I’ve corrected this.

I did not claim the people who use English on the Internet are likely native English speakers.

I made the converse claim—that people whose native language is English are likely to use English on the Internet.

This point was plainly addressed. Read carefully before going in guns-blazing.

Do you think Nigerians use the Internet as much as Americans?

Not all Internet users generate the same amount of content. In addition to Americans being proud blabbermouths in general, people from wealthy countries generate more content than those from poorer countries. The US is among the wealthiest countries in the world.

Although it is not the most representative, nearly half of all Reddit users are American. American media outlets have immense global reach. You can probably name four or five American media outlets just off the top of your head, even if you’re not American. The USA’s geopolitical power means people are always talking about American politics or what America’s leaders are doing, which draws engagement from Americans like a lamp draws moths. 7 out of the top 10 English-language YouTube channels are American (fully or partially).

It’s pretty much impossible to prove, but I think the claim that Americans generate most of the content on the Internet is likely true or very close to true.

It’s even more convincing if you exclude English Internet users from India, as a quick visit to any forum dominated by Indian users will cause you to quickly realise that the language used there is not really English but a mix of English and Hindi which is not comprehensible to non-Indians.