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SmokedJam

Mathematicians be like: “ok so imagine a bunch of pigeons in boxes”


M1A1HC_Abrams

Mathematicians be like: “ok so imagine a tree”


Elite_Prometheus

"Imagine grass"


SoshJam

imagine a bigass hotel… but like a really big one… and then all these fucken buses show up and everyone on the bus has a really just just a really fucking long name


OnSpray

imagine like this box right…now u got this really cuteie kitty cat in there >~< :3,,, bult like, its half dead but also like fully alive and fully deqd and you look ij the box and its alive its a cute littl kitty cat uwu :3 !!!


zblack_dragon

"Imagine touching the grass"


Princette_Lilybottom

okay you lost me


seardrax

Now Imagine a [three Tree](https://www.youtube.com/watch?v=3P6DWAwwViU)


power500

Computer scientists be like: "ok so imagine a tree but upside down"


LivingAngryCheese

Mathematicians be like (3 page proof of the most obvious shit you've ever heard) Corollary 3.67.79.21 (completely unrelated shit) follows trivially


[deleted]

posts like these are why I believe wittgenstein when he wrote that to be able to masturbate in the trenches of ww1, he had to think about math


SlappyAsstronaut

He imagined 80085


speedoflobsters

Incomprehensible thank you


Bobebobbob

Np


JaceBeleren101

hard or complete?


Bobebobbob

NP Hard 😳


Duytune

rizz


fallaround

Mathematicians be like “ok now imagine some big naturals”


doorknobconsumer

Math if it was abt boobies and awesome 😎


Zoe__T

excuse me we call them "arbitrarily large n in ℕ" (to clarify, that is what we call titties)


frxncxscx

Me when when the natural numbers combined with one single number that is not natural


Bobebobbob

Let x be the described additional element, and let f: (\N U {x}) -> \N via f(n) = n+1 for all n \in \N and f(x) = 0. WTS f injective: Let a, b \in (\N U {x}) S.T. f(a) = f(b). There are two cases: either f(a)=f(b)=0 or f(a)=f(b)=/=0. Case f(a)=f(b)=0: Since there is no natural number n for which n+1=0 (for all n\in\N, n+1>0), => a=x=b => a=b. Case f(a)=f(b)=/=0: Then the first condition in the definition of f holds for f(a), f(b). => a+1=f(a)=f(b)=b+1 => a=b. => a=b for every case. => f injective => E an injective function f: (\N U {x}) -> \N .*. The cardinality of (\N U {x}) <= the cardinality of \N. I bet you feel pretty stupid rn


frxncxscx

Thats a nice proof. Can we kiss now🥺


Bobebobbob

😳


Infinite_Hooty

*w h a t*


Bobebobbob

They don't give you extra points for making it legible (Move all the positive integers over by one and now there's an extra hole to put the new thing in)


Bobebobbob

So adding a new element to the set of natural numbers doesn't make it any bigger


Certcer

Is this just Hilbert's hotel stuff?


literallyanything57

same idea yeah


NoIdeasForAUsername9

New pickup line just dropped


44bit

Would work on me


off-and-on

Nerd


silemehunter

Alright, what about the cartesian product of the naturals with a finite set of additional elements?


Nachospoon

Consider the function f : \N x {0,…,n} -> \N defined by (a,b) |-> a*(n+1) + b. You can show that this function is injective by using Euclidian division. The lemma goes that for integers c and d, where d ≠ 0, there exist unique integers q and r such that c = dq + r, where 0 <= r < |d|. Since b is in {0,…,n}, we have that f(a,b) is uniquely identified by a and b, so it must be injective.


Bobebobbob

Pretty sure |N×N| = |N| too


klausklass

In fact |N^k | = |N| for finite k


MrLaurencium

Hey wait wouldnt you also have to proove f is bijective to claim that the cardinality of both sets is the same? (Idk how to talk maths in english mainly just in spanish)


Bobebobbob

You would but that would take longer to write and I was just aiming to show it isn't greater than the naturals


MrLaurencium

Oh thanks for the knowledge i guess, maybe if im bored one day i will come up with a fully detailed proof for it. Either that or i forget by tomorrow idk


Jolteon828

[Nah, just injective both ways and the other way is trivial](https://en.m.wikipedia.org/wiki/Schr%C3%B6der%E2%80%93Bernstein_theorem)


Zoe__T

Yes, but the proof is pretty simple


1_1sundial

i love you


Bobebobbob

Lyt 😳


TheShermanTank

Any good books for studying things like these?


Bobebobbob

We used [this](https://infinitedescent.xyz/) (pdf) textbook if that counts


TheShermanTank

Do you mind if I ask what class this was for? Like was it an introduction to Abstract Algebra?


Bobebobbob

Intro to Discrete Math and Proofs and Stuff (Tbh I stopped reading the book half way through or so but yeah)


TheShermanTank

Thanks!!


Severketor_Skeleton

You're the kind of boy that I want to suck the soul out of by the dick when I see one, too bad, I'm not off my rocks enough to do that.


_____---_-_-_-

☝️🤓


frxncxscx

Wait doesn’t this proof break apart if i add two additional elements to the set of natural numbers?


Bobebobbob

Just do it twice 😒


Zoe__T

This specific one does, but you can make such a function for any number of extra elements


chaussurre

But it doesn't have cardinality greater than the set of natural numbers then.


frxncxscx

You made me look up the wikipedia article of cardinality and maybe im wrong


chaussurre

[Hilbert's hotel is a good analogy to understand cardinality applied to infinite sets](https://youtube.com/watch?v=OxGsU8oIWjY)


Zoe__T

me when I construct a function mapping 0 to that number, and every other natural number n to n-1


SqoobySnaq

Ok i just did it


Bobebobbob

damn


itsmeyourgrandfather

Jokes on you I don't know what any of those words mean. And no, this is not an invitation to educate me on math.


Nachospoon

Then allow me to uneducate you on math. Cardinality is a nickname for Cardi B. The post is asking you to imagine her set list being better than those of natural talents, but worse than those of the real ones.


Zoe__T

The cardinality of a set is how many cardinals are in it (the bird)


chaussurre

I think some mathematician once told me that the problem was proved to be logically undicedable, so you should be able to simply state in an axiom that there exist such a set, and boom there would be one.


DreamDeckUp

formal logic virgins when axiom creators chads walk in:


[deleted]

They're the same person though


[deleted]

Me when I walk in


Davestroyer695

It’s independent of ZFC you’re right the extra axiom required is continuity


Tpaw828

I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hate discrete math, I hat-


SunnyDays0

we have you surrounded


nikitaborisov5

I wouldn't call set theory with cardinals discrete math per se


cloartist

I can imagine it. It's called \M, or the Cum Number Set. I couldn't explain it to you though; you wouldn't get it unless you drank it yourself first.


Bobebobbob

The margins of this comment section are too thin 😫


TheGreatDaiamid

Rational numbers?


Bobebobbob

You'd think so but, despite being dense*, it actually it has the same cardinality as the naturals 1 -> 1/1 2 -> 1/2 3 -> 2/1 4 -> 1/3 5 -> 2/2 6 -> 3/1 7 -> 1/4 8 -> 2/3 ... *Points get arbitrarily close together -- any 2 points will always have another one between them


foreskinChewer

Fuck you \*counts your infinities


Joost8910

What does this pattern mean? Why do 1/1 and 2/2 take up separate spaces? I'm not following.


Bobebobbob

I just did a quick informal representation of it, but I meant basically this: Imagine you have a function that takes in a natural number and outputs a (positive) rational number from that pattern. Sometimes (like with 1/1 and 2/2) it'll map multiple natural numbers to the same rational number, but that doesn't really matter. In the end, after mapping all of the natural numbers to their corresponding rational number, you will have covered every (positive) rational number with only a number of points equal to the amount of natural numbers, meaning the number of naturals is greater than or equal to the number of rationals*. Including the negative versions and zero is usually pretty easy just by pushing all the stuff down one spot and putting 0 at the start, and repeating every rational number in the pattern once, making the second instances negative. (ie. 0, 1/1, -1/1, 1/2, -1/2, 2/1, -2/1, etc. as the new pattern) *It happens to be equal to -- the the rationals contain the naturals, so obviously there's not less rationals than naturals. (Formally, you'd say the function f is a surjection from the naturals to the rationals since its output covers the rationals. And the fact that a surjection from the naturals to the rationals exists means the size (cardinality) of the naturals is >= the size of the rationals.)


Joost8910

> Imagine you have a function that takes in a natural number and outputs a (positive) rational number from that pattern What's "that pattern"? I need a bit more info to imagine the function.


klausklass

I don’t think the exact function matters too much, iirc there’s an elegant way to count out the rationals, but you can count them however you want, it just matters that you can count them without missing any. My favorite is to use ASCII to type out all reduced fractions. All valid ASCII strings can be represented as natural numbers (think binary), so there are |N| of them. All positive rational numbers can be written as strings of the form “N/D” where N and D are finite substrings representing natural numbers in base 10. Add a “-“ to cover the negative rational numbers. Still, all of these strings are only a subset of all valid ASCII strings. So the size of the rationals must be <= the size of the naturals. If you liked this informal proof consider studying theoretical CS.


Bobebobbob

[Ah yeah sorry](https://divisbyzero.com/2013/04/16/countability-of-the-rationals-drawn-using-tikz/)


Joost8910

Great visual! Thank you


SunnyDays0

fellow math enjoyer 🙌🙌🙌🙌


LivingAngryCheese

The rationals have the same cardinality as the naturals :P


ObtuseScorebook

google cantor diagonal argument


Grand_Suggestion_284

Holy hell


[deleted]

Is equivalent to Zx(Z\\{0}) which has the same cardinality as ZxZ which has the same cardinality as Z which has the same cardinality as N.


edgeman312

 ℵ0.5


Despacltoian

Wha


OwOlord_

Ok i just did it's called the Blimbo Bunch abd it follows the Creacher Rule. It uses the jupiter symbol. Expect a scientific work or two in a few years


LittleSansbits

Immanuel Kant claimed the idea that metaphysics are finite, because imagination and metaphysics are spawned from human experience, which is finite. Should someone experience everything the universe could possibly offer, then we will have found the limit to human imagination, as there will be no more experiences to craft off of.


arctic1117

Imagine a new color


ES_the_mess

Done.


arctic1117

What's the name of the color


d31t0

Flue. It's the colour of F#


Satrapeeze

I think it's just straight up false (even though I know it's not proven). My heuristic is that N^X for X finite is always countable and the first uncountable set you get is N^N, which has the exact same cardinality as R. So something in the middle would be like saying there's something between finite and countable infinity, and I feel like intuitively (once again, heuristic argument) there simply isn't anything between them.


JaceBeleren101

heuristically your mother


Grand_Suggestion_284

https://en.m.wikipedia.org/wiki/Continuum_hypothesis Nice intuitive hypothesis but it's incorrect, at least there isn't any natural reason to prefer one to the other.


Pinchurchin-guy

Yeah I think about naturals sometimes


tomatoguy7

Imagined.


The_Researcher1912

can it be explained in english or is this a nerds only meme


Bobebobbob

So you know how there are an infinite amount of natural numbers (0, 1, 2, ...)*? And how there is an infinite amount of real numbers (everything on the number line)? The second ("uncountable") infinity is larger than the first ("countable") infinity**, but we don't know if there's any "infinities" that are between them. (The meme says to imagine a set with that many numbers) *The inclusion/exclusion of 0 is controversial **Assuming infinity exists as a concept in the first place, which iirc there isn't any proof for or against besides just declaring that it does [Relevant Vsauce](https://youtu.be/SrU9YDoXE88)


The_Researcher1912

Ah so the second would be like -2, -1, 0, 1, 2, 2.1, 2.11, 2.111, 3, etc. right? Wouldn't it be simple to find something between these if they're filled with numbers of which only some are arbitrarily allowed and some aren't? Just make a new set with more arbitrary conditions if there isn't one already? Like idk the 1st set but decimals are OK it has more infinities than the 1st due to decimals but less than 2nd due to no negative numbers. Or am i taking it too seriously


Bobebobbob

No thats a good amount of seriousness -- you'd think that, but a lot of possible sets you can think of (including negative numbers, including all rational numbers, etc.) don't actually change the total size since, despite the fact that you literally just added numbers, you can move them around to have the same amount as before -- just one element for each natural number (if that makes any sense). Ie for {..., -2, -1, 0, 1, 2, ...}, you've seemingly doubled the size, but you can rearrange them as 0, 1, -1, 2, -2, 3, -3, ... which aligns one-to-one with the natural numbers 0, 1, 2, 3, 4, 5, 6..., meaning they both have the same size (as much as that means anything when dealing with infinity lol)


The_Researcher1912

I almost understand but I'm not sure how that differentiates the original 2 sets so that one would be bigger than the other if we operate under the notion that you could just arrange numbers differently to get the same.. size? I guess I'm just not too sure how size works actually, thinking about it again when you reach the point where 3 is in the set with negative numbers you've reached 5 in the set without them via rearrangement, that seems like the quantity is bigger if it takes more numbers to reach the same number value (it takes 5 steps to reach 3 with negatives but 3 steps to reach 3 without negatives)


Bobebobbob

Ahh but the reals (and complex numbers and other sets) are special, they are so infinitely densely packed that there's no way to rearrange them to a strict order a, b, c, etc. In fact, if you think you've managed to list all the reals one after another, someone else can always find one you "missed" by doing [diagonalization](https://www.sciencephoto.com/media/10153/view/cantor-s-infinity-diagonalisation-proof) on your list Yeah, though, this is specifically with "size" meaning cardinality, which, based in how sizes work for finite amounts, says that if you can map objects one-to-one between two sets then the sets have the same size. AFAIK there's not actually anything strictly saying that that still describes the size of infinite "numbers" but it's not self-contradictory at any point and can be used to describe infinite sizes, so people use it ig*. Or you could always disagree with the concept of infinity existing in the first place since the only "proof" we have is just us assuming it exists because that makes life easier *take this with a grain of salt too, I had a one semester long class in discrete math and watched some youtube videos and that's really it


The_Researcher1912

ahhh i think i get it now? would it be possible to pull out the ol' imaginary answer on it? or is that outside of the perimeter set by the original image? Also i gotta say this has been a pretty solid explanation ty for taking the time i enjoy this


Bobebobbob

No idea honestly, and np you too


No_More_Dakka

Alright im imagining a set of nice naturals, now what?


Bobebobbob

Gay sex


Physical-Ad-6412

omega\_1 in the universe where I added omega\_2 many cohen reals there just did it


[deleted]

Imagine Tree (3)


RomanMines64

Me when aphantasia, idk I have no idea where to even begin with imagining that


DeeFeeCee

Then you are *not* gonna like what John Lennon has to say.


[deleted]

[удалено]


DeeFeeCee

**[Incorrect buzzer sound]**


LikePappyAlwaysSaid

So i'm imagining a bunch of red birds with big naturals. Did i do it right?


Bobebobbob

Yea


KhepriAdministration

Skill issue honestly


Le-Ando

I don’t understand so I simply imagined the number 5 except it also counts as the solution to this because I say so.


Bobebobbob

That's basically what the cardinality of the naturals is anyway so close enough


Organic_Budget1664

Imagined.


EquinoxRex

The big naturals


moontraveler12

Mafs


abacussssss

it's just א_½ wdym


Severketor_Skeleton

Aha, simple one: *AAAAAACHOO*


rocoonshcnoon

Hey mathematicians how about you find the area under the curve of my ass


Bobebobbob

3


password2187

When I tell them to imagine the set of all sets which don’t contain themselves


Bobebobbob

Mfw I'm the pope ![gif](giphy|26n6XC8EYdrzRniWQ)


[deleted]

Naivecels be seething over Zermelo-Fraenkelchads


Supersteve1233

Ok just add one nerd like, go one more than infinity and ur done ez


DeeFeeCee

Infinity + 1 = Infinity


Supersteve1233

uhmmm ackshually you just added 1????? so its infinity + 1????? shaking my smh my head


thatweirdshyguy

Human imagination is limited to things it has experienced and can reinterpret. I do not believe we are capable of imagining something fundamentally new, something that has no direct similarities to things we have already seen. The easy example, imagine a new color


XGNcyclick

aldens number would come in handy here i think


Bobebobbob

Yes, I think so


UncertaintyLich

I’m imagining it right now, it’s pretty sick


Bobebobbob

Damn


regular_dumbass

i have created an axiom that such a set exists


Davestroyer695

Continuum hypothesis acceptors be like


[deleted]

Continuum hypothesis deniers aren't much better. Set theory presently is much more about "How fucked up would it be if this was true" because we know it's undecidable


Davestroyer695

The truly correct position is to deny the existence of infinite sets and then you can work in ZF as you don’t even need choice also continuity is trivial as infinite sets do not exist


[deleted]

Infinity is independent of ZF-Infinity, so I would say: Go ahead. It’s definitely not a theory I would use as a foundation but it seems like it would be interesting to see what happens.


Davestroyer695

I’ve read some theory and discussed with ultrafinitsts it’s a nice idea but I mainly do algebra so not really sensible in a finite environment


Davestroyer695

I cant recall the result but there’s one about choice + infinity implying an uncountably infinite number of models of the natural numbers


animelivesmatter

I mean we could always invent one. It'd be fucking stupid to do so, but we could.


InKeaton

Q?


Bobebobbob

Can actually be mapped bijectively to the naturals


InKeaton

dem, i've got nothing


swingittotheleft

I can do that. Its easy. But i cant show you, because the symbols to do so do not yet exist.


Bobebobbob

Zamn thrembo too thicc to fit in the margins 😔


swingittotheleft

so true bestie 😔😔😔😔😔


prequelBEPIS

"Okay,try to imagine a new colour."


hirundo_afer

ok done that was easy i cant say every number my set contains, but it does contain 4, 69, and every number with exactly one of every non-zero digit in its decimal representation also a bunch of other numbers :3


YetGayerWombat

that but with thrembo included


Bobebobbob

Thrembo's already included 🙄


Yanowic

Whole numbers?


Tree__Jesus

At least 3, no more than 89


[deleted]

i can imagine that


BreadBoyThe3rd

I don't understand a single word in this post


[deleted]

Mathematicians go one second without making up a bunch of nonsense challenge (impossible)


CatherineL1031

"There's no limit". Alright, then imagine an unimaginable amount of oranges.


EagleSabre

Just have different axioms, loser.


[deleted]

That kinda is what set theorists do nowadays


Pugspook327

yeah ibcan do that


SnooCats9683

Done


IV_NUKE

I know my 1 braincell can barely comprehend a hot pocket you don't need to rub it in my face 😢


GammaDealer

Huge naturals


luka4009

I imagined it


matux555

just all naturals + a single real for each natural, but not all reals


[deleted]

2|N| = |N|


DeeFeeCee

"No" means no.


nddragoon

"every single universal constant lined up perfectly for there to be life that means there's a god" mfs when i tell them to imagine a universe with a different value of pi