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Primes (lemmy.ml)
submitted 1 year ago by [email protected] to c/[email protected]
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[-] [email protected] 53 points 1 year ago

2 may be the only even prime - that is it's the only prime divisible by 2 - but 3 is the only prime divisible by 3 and 5 is the only prime divisible by 5, so I fail to see how this is unique.

[-] [email protected] 22 points 1 year ago* (last edited 1 year ago)

Exactly, "even" litterally means divisible by 2. We could easily come up with a term for divisible by 3 or 5. Maybe there even is one. So yeah 2 is nothing special.

[-] [email protected] 21 points 1 year ago

"Threven" has a nice ring to it now that I think of it.

[-] [email protected] 9 points 1 year ago
[-] [email protected] 3 points 1 year ago

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[-] [email protected] 3 points 1 year ago* (last edited 1 year ago)
[-] [email protected] 42 points 1 year ago

Even vs odd numbers are not as important as we think they are. We could do the same to any other prime number. 2 is the only even prime (meaning it is divisible by 2) 3 is the only number divisible by 3. 5 is the only prime divisible by 5. When you think about the definition of prime numbers, this is a trivial conclusion.

Tldr: be mindful of your conventions.

[-] [email protected] 12 points 1 year ago* (last edited 1 year ago)

Yes, but not really.

With 2, the natural numbers divide into equal halves. One of which we call odd and the other even. And we use this property a lot in math.

If you do it with 3, then one group is going to be a third and the other two thirds (ignore that both sets are infinite, you may assume a continuous finite subset of the natural numbers for this argument).

And this imbalance only gets worse with bigger primes.

So yes, 2 is special. It is the first and smallest prime and it is the number that primarily underlies concepts such as balance, symmetry, duplication and equality.

[-] [email protected] 8 points 1 year ago

But why would you divide the numbers to two sets? It is reasonable for when considering 2, but if you really want to generalize, for 3 you’d need to divide the numbers to three sets. One that divide by 3, one that has remainder of 1 and one that has remainder of 2. This way you have 3 symmetric sets of numbers and you can give them special names and find their special properties and assign importance to them. This can also be done for 5 with 5 symmetric sets, 7, 11, and any other prime number.

[-] [email protected] 4 points 1 year ago

Not sure about how relevant this in reality, but when it comes to alternating series, this might be relevant. For example the Fourier series expansion of cosine and other trig function?

[-] [email protected] 3 points 1 year ago* (last edited 1 year ago)

But then it is more natural to use the complex version of the Fourier series, which has a neat symmetric notation

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[-] [email protected] 40 points 1 year ago

2 is a prime though isn't it

[-] [email protected] 55 points 1 year ago

Yes, but it's the only even one. Making him the odd man out

[-] [email protected] 39 points 1 year ago

It is but if feels wrong

[-] [email protected] 2 points 1 year ago* (last edited 1 year ago)

It pretends to be prime and we all go along with it to avoid hurting its feeling.

[-] [email protected] 27 points 1 year ago

The meme works better if it's 1 instead of 2. 1 is mostly not considered a prime number because a bunch of theorems like the fundamental theorem of arithmetic would have to be reworked to say "prime numbers greater than 1." However, just because 1 is not a prime number doesn't mean it's a composite number, so 1 is a number that is neither prime nor composite.

[-] [email protected] 9 points 1 year ago

2 is a prime number, but shit ton of theorems only apply to odd prime numbers, and a lot of other theorems treat 2 as a special separate case, because it behaves weirdly.

[-] [email protected] 7 points 1 year ago

Two is the oddest prime of them all.

[-] [email protected] 7 points 1 year ago

2 is a prime number though…..

Is it Just because it’s the only even one?

[-] [email protected] 7 points 1 year ago

Often things hold true for all primes except 2. You come across things like "for all non two primes"

[-] [email protected] 4 points 1 year ago* (last edited 1 year ago)

Any examples? Sounds like you mean the reason why one is excluded from the primes because of the fundamental theorem of arithmetic.

[-] [email protected] 3 points 1 year ago* (last edited 1 year ago)

No, he's right. "For any odd prime" is a not-unheard-of expression. It is usually to rule out 2 as a trivial case which may need to be handled separately.

https://en.wikipedia.org/wiki/Fermat%27s_theorem_on_sums_of_two_squares

https://www.jstor.org/stable/2047029

https://www.jstor.org/stable/2374361

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[-] [email protected] 2 points 1 year ago

Like what? Genuine question, have never heard of this.

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[-] [email protected] 3 points 1 year ago

And how is "even" special? Two is the only prime that's divisible by two but three is also the only prime divisible by three.

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[-] [email protected] 7 points 1 year ago
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[-] [email protected] 7 points 1 year ago

I don't get it, why does adding a hand move to the next prime?

[-] [email protected] 12 points 1 year ago

🚨 NERD ALERT🚨

Go define a vector space, nerd.

Go compute the p value of you being cool

Go integrate f(x)= 1/x on the domain (-1,1)

This is meme-ville population: me

Take a hike.

[-] [email protected] 4 points 1 year ago

Spoiler: p < 0.05

[-] [email protected] 3 points 1 year ago* (last edited 1 year ago)
  • let V be you mom’s vagina, a vector space over the field of pubes. We define my d as a vector such that d is in V. Thus my dick is in your mom’s vagina.

  • In this vector space p values are not defined, but I can assure you that my pp is > 9000.

  • The integral of f(x)=1/x from -1 to 1 does not converge, just like how your father is never coming back from buying milk. The principal value of that integral tho is 0, just like the amount of hugs you got as a kid.

  • math is cool, you just too stupid to get it.

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[-] [email protected] 5 points 1 year ago

Pretty sure that when we plug in a correction factor for the relative age of the Fediverse userbase, "today's lucky 10,000" becomes more like "today's lucky 10 million"

[-] [email protected] 2 points 1 year ago

Lucky ten thousand

I kinda wish it was calculated for the world instead of the US though

[-] [email protected] 2 points 1 year ago

It's just the way the power rangers combined their forces

[-] [email protected] 6 points 1 year ago

Oh yeah? What about 0? And 1?

[-] [email protected] 36 points 1 year ago* (last edited 1 year ago)

They're not prime. By definition primes have two prime factors. 1 and the number itself. 1 is divisible only by 1. 0 has no prime factors.

[-] [email protected] 16 points 1 year ago

Commonly primes are defined as natural numbers greater than 1 that have only trivial divisors. Your definition kinda works, but 1 can be infinitely many prime factors since every number has 1^n with n ∈ ℕ as a prime factor. And your definition is kinda misleading when generalising primes.

[-] [email protected] 9 points 1 year ago* (last edited 1 year ago)

Isn't 1^n just 1? As in not a new number. I'd argue that 1*1==1*1*1. They're not some subtly different ones. I agree that the concept of primes only becomes useful for natural numbers >1.
How is my definition misleading?

[-] [email protected] 3 points 1 year ago* (last edited 1 year ago)

It is no new number, though you can add infinitely many ones to the prime factorisation if you want to. In general we don't append 1 to the prime factorisation because it is trivial.

In commutative Algebra, a unitary commutative ring can have multiple units (in the multiplicative group of the reals only 1 is a unit, x*1=x, in this ring you have several "ones"). There are elemrnts in these rings which we call prime, because their prime factorisation only contains trivial prime factors, but of course all units of said ring are prime factors. Hence it is a bit quirky to define ordinary primes they way you did, it is not about the amount of prime factors, it is about their properties.

Edit: also important to know: (ℝ,×), the multiplicative goup of the reals, is a commutative, unitary ring, which happens to have only one unit, so our ordinary primes are a special case of the general prime elements.

[-] [email protected] 3 points 1 year ago

Oof, I remember why I didn't study math 😅
But thanks for the explanation

[-] [email protected] 2 points 1 year ago

Yeah, higher math is a total brainfuck :D You're welcome.

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[-] [email protected] 5 points 1 year ago

0 has all the factors. Itself and any other number.

[-] [email protected] 4 points 1 year ago

Put them in a sieve of Eratosthenes and see what happens.

Spoiler, they aren't.

[-] [email protected] 3 points 1 year ago
[-] [email protected] 18 points 1 year ago

@lowleveldata @HiddenLayer5

You asking why 9 wasn’t at the party?

It’s because he’s a square

[-] [email protected] 6 points 1 year ago
[-] [email protected] 9 points 1 year ago
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this post was submitted on 09 Aug 2023
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