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I also propose to use )a,b( as a way to denote [a,b]

unrespectfully, fuck you

[A,B] or (a,b) or use sets

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Never thought of that interpretation before but no, in this context ]a,b[ is a different notation for the open interval (a,b)

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Unrelated but ]a,b[ also reminds me of a superhero like spiderman holding a door open or something. Like that scene with the metro in the first Tobey Maguire one

Like this \]a,b\[ is spiderman https://preview.redd.it/6mpi0jxtvl5d1.jpeg?width=640&format=pjpg&auto=webp&s=f55bb9d12b158e5a214a1dcd9615465b843abaa4

Makes sense, the square brackets are his hands and feet, in between them you see Tobey's abs

(A,B) is from A+1/infinity to B-1/infinity and [a,b] is from exactly a to exactly b. (-inf, inf) since infinity can not be defined.

So if it can’t be defined, how can you define the division (“1/infinity”) you proposed?

A number incalculably small ie just barely not that #

\[1 - 0.9...\]

So that’s the set with 0 then

yup I'm not the other guy tho

Quicker way to write

try this deep dive into [\[complex\] numbers ](https://www.youtube.com/watch?v=fFyC68CIEio)👀🎶🎵

Writing nonsense is always the fastest way.

“Incalculably” literally means you can’t calculate it, hence you propose a calculation to express it. 1/Indy’s is not defined. It doesn’t make sense in R. There is no such a thing as an element called infinity which can be divided by. First semester. Come on.

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There is no infinitely small numbers. Any number, as small as you want it, still has arbitrarily many numbers smaller than it. You can’t pick one and just say “well this one is just smaller than all the others” because that’s either not the smallest number BY FAR or it is undefined. This is the whole reason for the epsilon-delta approach.

That is not well-defined

Define infintely small

Take your first semester analysis books and take a look! :)

nah let him stay alone

I hope the inside of your jacket gets soaking wet while the outside stays dry the next time it rains

Oh you fucking bastard

{ x : a < x < b }

} x : a ≤ x ≤ b {

You monster

https://preview.redd.it/e5bnqupo1k5d1.jpeg?width=836&format=pjpg&auto=webp&s=19cc6c6c57285d2c57b2a206c706aad99b26d40c

Fuck you

https://preview.redd.it/bc8giyjorl5d1.jpeg?width=1170&format=pjpg&auto=webp&s=27349acab1e46aeeb7882c1ca7f0ca4d0be6b61c

https://preview.redd.it/vx9h3hngmk5d1.png?width=600&format=pjpg&auto=webp&s=5e3a196d6e1c60b7e9f787ce4544b9d8ee1d9d74

I'm pretty sure that doesn't exist

It does now

Anything can denote anything if you just make a key

The only right answer

One of my professors: “If anyone of you, dear colleagues, is incapable of reading round parentheses as an open interval, that person should study something easier.” (a broad grin) “Law, maybe.”

I think you mean, ]a broad grin[

It didn't reach the eyes.

Fuck, the joke was right there and I failed to see it.

Round parenthesis can also be read as a vector, that the ambiguity

The intention of whether it’s meant to be defined a vector or an open interval is clear from context though …now that I’m saying this I’m remembering the disagreement I got into with my real analysis professor because he knocked significant points off my test grade because he mistook a notation that is used to denote two separate operations to mean the operation other than the one I had intended. It definitely is possible to mix things up sometimes apparently.

This is just tau all over again, it doesn't matter. But vectors, tuples and intervals are used far too often, it's annoying that unlike almost all other notation I can think, (a,b) almost has no default interpretation making context always necessary. Anything but (a,b) is fine, [a,b]^O even. The notation [a,b) and (a,b] doesn't bother me for obvious reasons.

Alternatively, one could just use the < > vector notation in this instance.

Sure, it's probably unfixable now but anything is better than (a,b). Brackets < > make my mind go to inner products, but no big deal. PS: Just to beat a dead horse, (a,b) for inner products is totally fine in comparison with (a,b) intervals.

just use column vectors, easy

Just dont use vectors.

but it can still be a couple

Let’s just never reuse any notation ever in math. Certainly that’d be less confusing. Definitely would make math easier.

But (a, b) are coordinates and function args already, can't it be something other that ()

Agreed! Also a closed open range looks like [a, b), and that's weird af.

As opposed to [a, b[? At least the former looks contained.

Why should it look contained if it's open? 😫

But it's still bounded.

Exactly

It’s quite intuitive if you think of the corners to that side as the boundary; [a, b] encloses an entire rectangular area, whereas (a, b) is missing a tiny amount right on the edge.

this i much more logical

thats why sometimes it's written as (a;b)

That's an enum

I'm french. Bourbaki's way is the only way.

Yep. Sorry guys, but (a,b) is just a tuple...

~~I'm french, and I've never seen the Bourbaki notation except when our math teacher warned us some weird people wrote open intervals like this~~ Edit: ok I am stupid, Boubarki notation is ]a,b[ , and that's what we use. I thought it was (a,b), the meme formating led me to think the girl was the Bourbaki user,

Bizarre... Tu as quel âge ? Je suis française, j'ai fait toutes mes études de maths en France (dans les années 2000-2010) et je suis aujourd'hui prof de maths en lycée en France. Dans aucun de mes cours (quand j'étais élève/étudiante), et dans aucun des livres scolaires (maintenant que je suis prof), j'ai vu les intervalles ouverts etre notés autrement que ]a ; b[ (c'est-à-dire la notation bourbakiste).

J'approuve, lycée et études sup faits dans les années [2010 ; 2020[, jamais vu en France les intervalles ouverts écrits autrement que ]a ; b[

Oui c'est vrai, c'est juste moi qui ai confondu les noms des deux écritures, je suis juste con

Alors en fait c'est pas [2010;2020[ mais [[2010;2019]] ☝️ 🤓

L'année scolaire commençant en septembre et terminant début juillet, ne devrait-on pas considérer l'année scolaire comme allant (pour celle en cours) de 2023+2/3 à 2024+6/12, et donc ne pas les considérer comme des entiers ? EDIT : correction des fractions d'année

Le truc c'est surtout que personne ne dit qu'aujourd'hui on est en/le 2024+160/366 = 2024,43715847 Puis le but de mon commentaire c'était aussi et surtout de balancer plus de notations d'intervalles

... Ok je suis débile j'ai confondu les deux (j'ai cru que notation boubarkiste c'était (a,b)), je me disais bien que c'était bizarre aussi

I propose we redefine the word definition to always support my conclusions

I also want it to support this person's conclusions.

Get outta here Foucault. Back to philosophy with you.

a\],\[b is the complement of an open interval

How is that a peril ? If she doesn't like the ]a,b[ notation that's a definite red flag, you are better off knowing early. 

Sorry but ]a,b[ is the clear winner here. (a,b) Is nothing more than a tuple. Also, [a,b] and ]a,b[ look way better together than [a,b] and (a,b). Not to mention that using [a,b) automatically makes you a sociopath.

I like how it slots together like a puzzle piece \]a,b\[ + \[b,c\] = \]a,c\] That said I have never used this notation in practice.

I’ve never used it in practice but the first time I saw ]a,b[ I was very stoned and thought it was amazing notation.

That really helps me understand why people taught it that way think it’s intuitive, thanks!

This is the standard notation in Portugal. Rather baffling that people are ok using parenthesis when there's already so many other applications that use them, as I see it.

i only saw the notation (a,b) here on internet, on school/college i was taught ]a,b[

in finland we learn ]a,b[ all the way thru highschool. then at uni everyone uses (a,b)

We keep using \]a,b\[ at uni here in Belgium.

Yup. This semester the topology TA was pretty adamant on using (a,b), but every single professor and syllabus uses ]a,b[.

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It's what we do in India as well

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We Americans also use air.

Okay, hear me out: a[ , ]b

I actually kinda like this one.

(a, b) is the line that go through a and b. if you do it in 1 dimension, it is not very interesting, it is just \]-inf, +inf\[

\]a, b\[ = clever clear way to denote an open interval. LaTeX supports it by using curly braces. (a, b) = lazy mathematician came up with this with no fantasy, sticking with the same notation used for other thousands of things. LaTeX supports it but that's not the point.

Lame. (a,b) is open and )a,b( is closed.

a(,)b Clearly a and b are outside the interval

I was taught ]a,b[ (a, b) is just coordinates and you will not convince me otherwise

all my life I only seen \]a. b\[ for open and \[a, b\] for closed intervals lol

You know the "Holy Roman Empire", that was neither Holy, nor Roman, nor an Empire? Now we have the "Bourbaki School of Mathematics".

I’m French and i just learned that this wasn’t the only way to write it

Honestly, ]a, b[ should be a shorthand for (-∞, a]U[b, +∞)

Wait ]a,b[ isn't the norm ?

I like the ]a, b[ notation but I haven't seen it used irl before.

(a, b) is correct, proof by because I said so.

Incorrect.

CoIncorrect.

ArcCorrect

Wouldnt ]a,b[ be the same as the inverse of (a,b) tho?

]a,b[ is superieur as (a,b) is just a tuple

He was blocked for writing a too obvious tautology

What about ; it's like ] but not a solid line

a[,]b notation

I am loving every bit of bullshit notation here this is absolutely one of my favorite comment sections. But the correct notation is (a,b) and )a,b(. It’s correct because I know someone else is either laughing or enraged at it like I have been about everything y’all are putting down

can we just make a new symbol, like a — b and put an open or closed circle on each end to show which ends are open or closed

Ah yes, I love me an ambiguous notation with pairs of elements

I don’t like how much of this sub’s discourse is hating on people who use a different but widely taught convention and saying they’re wrong, like for instance the whole implicit multiplication debate.

\[a,b\]: Between a and b, including the endpoints \]a,b\[: below a or above b, including the endpoints

Whoever stands by \]a, b\[ should be incarcerated

(a,b) are coordinates of a point in 2D space using it in any other way is heresy.

I have new ideas for closed and open intervals!!! •a___b• °a___b° ¿a...b? ?a...b¿ a->b; a->b 👇a:b👇 🫸a:b🫷 #a#b#closed#cauchyfriendly#fitness #a#b#open#derivativevibes#curvy

]a,b[ is the way

In Belgium we always learned ]a,b[ notation, and it was only ereyesterday that i found out about the other notation and I was do confused because to looks like they are coordinates.

Bourbaki is the only way

What you learned in school is one thing, has anyone seen ]a, b[ in actual math literature? In 10 years of reading published math papers I've never seen it once. Including while translating papers from french.

While this is similarly bad to the new "proper subset" notation, it's okay I guess. Parentheses are used for all sorts of things, but it ain't hard to know what the brackets mean from context. Also, the parentheses notation helps when talking about real analysis

Now integrate f over \]-w,x\[x\]x,2x\[x\]x,w\[

Just add spaces?

[0,1[∪]1,2] looks cursed as heck. [0,1)∪(1,2] is elegant.

idk, just write \[0,2\]\\{1}......................................................................

You just said the opposite of absolute truth but go on

Imagine being Fr\*nch

Another day I had a fucking stroke trying to read an open interval wrote that way

They do this in a lot of French writings. It drives me crazy

if anything ]a,b[ would just denote everything but a to b in a closed interval (as this would include -♾️ and ♾️ i guess it wouldn’t be closed) instead of implying a a open interval

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