/mg/ - Math General

>>9070010
Hey, does anyone remember that guy who made a group study on probabilistic robotics (or something like that)? I was wondering if someone participated and if the experience was worthwhile. It'd be cool to maybe gather and work through some textbook about an interesting topic (I have some in mind, but I'd like to hear other proposals first).

>>9070022
>probabilistic robotics
Do you mean topological robotics?

>>9070024
I'm talking about this https://warosu.org/sci/thread/S8418462

Algebra night tonight :)

>>9070091
But anon, it's Friday! Aren't you going to accept Stacy's invitation to the Diff Geo party at Chad's place? It's not every week that his parents have to attend a conference in Reykjavík.

>>9070010
Here's a very interesting paper about the computational limitations of calculating the maximum interval in an initial value problem for an ODE
http://www.ams.org/journals/tran/2009-361-06/S0002-9947-09-04929-0/S0002-9947-09-04929-0.pdf
Pretty interesting desu. It also has a lot of references to other works on computability of ODEs.

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>preparing to move
>haven't read one page of math this week

>>9070010
inb4 the thread is deleted again because one of the mods is a physishit Nazi who hates anything pure.

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>>9070494
>tfw packing

>>9070010
Nice image by the way, I'm going to edit it with a mathematics textbook later today (I need to do my groceries now). I'll be back in 2-3 hours. Leave suggestions for what maths book you'd like in the image.

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>>9070548

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>>9070548

>>9070562
>>>/sci/physics general

>>9070550
This book seems erotic.

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>>9070566
But the category of 2D HQFTs is equivalent to the category of semisimple graded Frobenius algebras.

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>>9070577
Do you expect the freshmen in /mg/ who don't know the relation between math and physics to even know what an algebra is?

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>>9070579
No but I expect them to stfu about things they don't understand like the good mannered slaveboys they are.

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>...and here's our son's room, he's quite the little mathematician

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>tfw no satisfactory definition of mathematics

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is the reason you can throw in or exclude the Y variable willy-nilly that the distribution without Y is a perfectly fine distribution, it might just not be a distribution we know, so we need to use the joint one with Y (to find the marginal one without Y)

>>9070701
"Mathematics is the study of mathematical structures" is a perfectly satisfactory definition.

>>9070022
>>9070024
>>9070031
>robotics
This is the math general. Feel free to discuss engineering topics anywhere else.

>>9070786
Even in fifth grade we were told that any definition using the word which is being defined is bad.

>>9070789
Nah, you're just a brainlet. "Mathematical structure" is prior to "mathematics". Mathematics is precisely that which is the study of mathematical structures, which may be defined in such a way that does not invoke mathematics which is a posterior term. For example, you may define a mathematical structure as "an object whose essential properties are exhausted by its formal definition" after which you may go on and extricate "object", "essential property" and "formal definition" if you feel so inclined.
A certain degree of 'nesting' is inevitable in any language. Sooner or later you reach a 'definitional bottom' where it is impossible to avoid circularity. Fortunately, "mathematics" is nowhere near that bottom.

>>9070801
It is the same as saying "physics is the study of physical phenomena". Physical phenomena are prior to physics. They exist even when you do not study them.
It is the same with mathematics. Hopefully even a physishit brainlet like you will get it now.

>>9070786
This depends on the definition of mathematical structure which was not satisfactorily defined in the last thread.

It's still unclear whether there exists an object whose essential properties are not exhausted by its formal definition.

>>9070812
>It's still unclear whether there exists an object whose essential properties are not exhausted by its formal definition.
It couldn't be farther from unclear. You are such an object. The claim that there exist objects whose essential properties are not exhausted by their formal definition is equivalent to the fact that the map of a territory is not the territory itself.

>>9070820
>You are such an object.
What is an example of one of my essential properties that does not follow from my formal definition?

>>9070820
>>9070812
What is unclear is whether there exist [math] abstract [/math] objects whose essential properties are not exhausted by their formal definition, which is why defining mathematics as "the study of abstract objects" is most likely over-general/defining "too much".

>>9070828
The fact that you exist in a material sense. This cannot follow from any formal definition, otherwise unicorns would be made real by a sufficiently thorough formal definition, which I would assume anyone here would deem absurd (but then again, you never know, given how many brainlets seem to gather in these threads).

>>9070808
>physishit
Don't be mean please, I have not taken a physics class past highschool.

And while you are probably right that "mathematical structure" is before "mathematics", I was more taking about the definition not being all that complete if you don't go on and define what "mathematical structure" is.

If I would respond with that definition to any person asking me what mathematics is, the question what "mathematical structure" is is inevitable, I they wan't to understand mathematics.

>>9070837
It is nonetheless the most correct way to go about it. Read the rest of the posts. (Redditposting is rude too by the way. Don't expect people to be polite to you when you don't play by the house rules.)

>>9070840
>It is nonetheless the most correct way to go about it.
I was not arguing that.

>Redditposting
Not once in my life have I ever posted anything on reddit.

>house rules
written where?

>>9070844
They are unwritten rules. You may or may not have been to reddit (you may or may not be lying about it) but you are, regardless, inserting too much whitespace in your posts.

>>9070844
>written where?
"written by whom?" would be a better question. And I'll answer it - by God, which is to say by Me.

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>>9070548
As promised, made the OP >>9070010 more salient to mathematics. Grudgingly using this >>9070550 suggestion since no other mathematics books was offered. Hope you like it anon.

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>>9070883
That's a great edit, thanks for taking my suggestion

>>9070588
So says the idiot who thinks Furstenberg's proof that there are an infinite number of primes has nothing to do with infinite sets.
>>9067441
>Can't you prove Euclid's theorem with topology? You don't even need to appeal to infinities lmao
I've yet to see you say non-retarded shit whenever you opine on something I'm familiar with, so I have reason to doubt you know what you're talking about whenever you vomit your TQFTs and all the other garbage.
I even remember someone a few threads back saying that they don't reply to your posts because you either write things that follow from definitions or write nonsense, something like that, I can't be bothered to find the post and quote it directly.

So, yeah: >>>/sci/pg

>>9070833
>The fact that you exist in a material sense. This cannot follow from any formal definition
What counts as a formal definition? Can I be defined by 'the person born in [specific hospital room] at [date and time of birth]'?

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>>9070898
No, no, it's not nonsense bro you just don't have the physical """""intuition""""" to understand that!
Besides, mathematicians crying about rigour are hypocritical because they consider conditional proofs valid.

>>9070931
What's not rigorous about a conditional proof?

>>9070933
I was being sarcastic. That's the sort of dumb shit 2huposter pulls out of his ass.

>>9070787
Thanks for completely missing the point of the post anon, but I guess no one here actually wants to do any maths, so instead they opt to cry endlessly about barely nonexistent physics posts.
I wouldn't even care if they provided original mathematical content, it's not that fucking hard. Anyone who has a passing interest in maths should be able to at least start a discussion about a mathematical topic they like, like linking papers/articles/open problems/interesting theorems/etc...
I know not everyone here is a PhD student or something, but there are some journals (like this one http://www.rose-hulman.edu/mathjournal/archives.php) which are geared towards undergrads, with articles made by other undergrads. They're usually pretty cool and explain everything from the basics, I really recommend it.
Here there are more online journals http://www.stat.berkeley.edu/~mathsurv/ejournals.html
Here's one about classical Euclidean geometry because I'm a sucker for it http://forumgeom.fau.edu/
There's also this very nice introductory article to Hyperbolic Geometry (I still haven't finished it, but it's good so far) http://library.msri.org/books/Book31/files/cannon.pdf, and there are others still.

>>9070942
>Thanks for completely missing the point of the post anon
...which is?

>>9070944
>I was wondering if someone participated and if the experience was worthwhile. It'd be cool to maybe gather and work through some textbook about an interesting topic

Where can I obtain the necessary physical intuition to make rigorous proofs?

>>9070942
Assuming anything that is not proven (except axioms lol) cannot yield a proof. Any mathematician thinking otherwise is an idiot.

>>9070984
Right and wrong. Those mathematicians that dislike the supposed "lack of rigor" in physics should also reject statements proven assuming generalized RH/CH.

>>9070984
I'm pretty sure you quoted the wrong post.

>>9070950
And how does that have anything to do with math?

>>9071014
>What does doing math have to do with doing math?

>>9070984
>>9070989
In case anyone is confused, this is pasta, and the source is a dumb conversation between the 2huposter and another physishit: >>9062479 & >>9062945

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>>9071020
>engineering
>doing math

>>9071026
>Hey, did any of you do that engineering related thing? Do you think it'd be worthwhile to do it with a math topic?
>lol anon, engineering is not math

>>9071029
Nothing you've said points to starting a similar program in mathematics. The only thing you posted is an apropos about an engineering (robotics) conference.

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>>9071023

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>>9071029
Do what with a math topic? Construct mathematical equivalents of robots? Go to conferences? Do even you know, you semen slurper?
Bunch of weasels who treat this thread as a clubhouse where you dump anything that pops into your head because "lol math is cool I like math too bros we use mock theta functions in physics and check out my path integrals dude, by the way there's this robotics club this guy made I heard about, are you in it?".

Piss off.

I'm building a numerical model to examine seed dispersal in marine environments...

I'm currently thinking of a novel way to calculate wind speed and direction for surface currents atm. So I'm thinking of using real time data to create two weibull distributions so that the dispersal influenced by surface currents is somewhat realistic.

>>9071032
>>9071048
1.- Pick a math topic (for example, diff geo, maybe something more concrete)
2.- Pick a textbook about said topic
3.- Work through said textbook and give each other help if necessary
Gee, that was hard to understand.

>>9071079
The initial post is very vague.
>work through some textbook about an interesting topic
Well excuse me for not being exactly sure about what topics are interesting to you when you spent the entirety of that post writing about a robotics reading club. You could've just as well read that as a suggestion to start a manga reading club.

>>9071085
If I mentoined that robotics guy at all is because it's the only example I know of someone doing this sort of thing in /sci/. I didn't mention that the topic was meant to be a math one because I thought that was a given since we're on /mg/, but I guess I should have specified anyway.

>>9071095
>I didn't mention that the topic was meant to be a math one because I thought that was a given since we're on /mg/
Yes, /mg/, which has been in total disarray for the last few threads because more and more of us are annoyed that so many posts are only tangentially related to math. Here's a perfect example: >>9071077

>>9071077
Not math. Feel free to post this elsewhere.

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great thread so far!

>>9071101

Well, if you're creative you could suggest ways to numerically represent wind...

Geez, asked to share a mathematical problem, and it's brushed off. You want me to write it out or something?

>>9071106
Not math? :O Omg, Reeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeseeese

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Okay guys, I recently went to stay at a hotel with 3 friends, it was on a Sunday.
The room costs $60. We each put down $20 on the counter, but there was a $5 Sunday discount, so the guy at the desk put 5 $1 bills on the counter, we each took 1 and gave the remaining 2 as a tip to the guy.
When we got to the room we did the math.
We each paid $19 dollars + the $2 tip.
19 x 3 = 57 + 2 = 59.
Where is the last remaining dollar?

>>9071110
Simulating some natural phenomenon is not a maths problem. Just because you use maths doesn't make it into one.
If you want to talk about numerical approximations in and of themselves, feel free to do so. [math] That\ \mathbb{is} [/math] math.
(Of course, there's a chance you're only fishing for (you)s, given the formatting of your post.)

>>9071116
>We each paid $19 dollars
No you didn't.

>>9071116
It's 50/50.
Either you have the dollar in a pocket you haven't checked yet, or you don't.

>>9071117
>Just because you use maths doesn't make it into one.
Did I miss the 'pure math general, nothing applied is allowed' sign on the way in?

>>9071124
"Applied math" is not mathematics.

>>9071120
We each put down $20 and got $1 back, hence $19

>>9071125
>"Applied math" is not mathematics.
What else could it be but math?

>>9071125
Please be bait.

>>9071124
>>9071125
Of course "applied math" is not mathematics. "applied math" simply doesn't exist.

>>9071124
>applied
Don't mention that word here, trust me on that...

>>9071116
>with 3 friends
>We each put down $20
>The room costs $60
You got scammed

>>9071135
>"applied math" is not mathematics

see
>>9071133

>>9071137
>Don't mention that word here, trust me on that...
I don't see any 'applied math' general, where am I supposed to mention it if not here?

It seems a better fit than the other threads

>>9071143
I am just warning you that mentioning the a-word will lead into autistic discussion you do not want to have.

>>9071139
"applied math" doesn't exist. From this simple fact it follows that "applied math" isn't math.

>>9071147
>"applied math" doesn't exist. From this simple fact it follows that "applied math" isn't math.
https://en.wikipedia.org/wiki/Applied_mathematics

>Applied mathematics is a branch of mathematics

>>9071143
>I don't see any 'applied math' general
Why not create one then? We don't discuss fairy tales in this thread.

>>9071149
this is the last time I will warn you DO NOT MENTION THE A-WORD

>>9071150
>Why not create one then? We don't discuss fairy tales in this thread.
see
>>9071149

>>9071133
>>9071134
Calling a dog a camel doesn't make it into one.
Just because the term "math" appears in after "applied" doesn't mean you're talking about mathematics.

>>9071149
Wikipedia is, as with many other things, wrong on this subject.

What are some good resources to study Applied Math?
I want to do some research in it in the future.

>>9071154
>Just because the term "math" appears in after "applied" doesn't mean you're talking about mathematics.
https://en.wikipedia.org/wiki/Applied_mathematics#History
>Historically, applied mathematics consisted principally of applied analysis, most notably differential equations; approximation theory (broadly construed, to include representations, asymptotic methods, variational methods, and numerical analysis); and applied probability.
When did any of these become non-mathematics?

>>9071156
This is the math general. Ask stupid question in >>>/sci/sqt

>>9071156
>>9071158
Daily reminder to use some other thread for discussing fairy tales and other such bullshit.

>>9071158
When they were not employed in the study of mathematical structures. Applying mathematical tools in other domains [math] \neq [/math] mathematics.
The study of, for example, differential equations, is mathematics. Using differential equations to model some natural phenomenon on the other hand, isn't. That pertains to physics, chemistry, biology etc.

>>9071156
>>9071160
He means, that unless you wan't top have competently pointless discussions about autistic topics (such as "is a-word math math?") , then you should better not be here.

This is a math general only in name, in truth it is a-word autistic shitposting general.

>>9071167
it seems you have a highly non-standard definition of mathematics

>>9071158
By that definition any science which uses quantitative methods is applied mathematics. Why not discuss economics here while we're at it? We've been over this shit already. "Applied mathematics" is a meaningless term. It's either too broad or too narrow. Never useful.

>>9071172
Nu-uh: I have a [math] correct [/math] definition of mathematics.

Umm... There is no defined differences between a-math and p-math.

Just some people like dealing with real world problems, and others like dungeons and dragons.

>>9071174
>Why not discuss economics here while we're at it?
Quite the strawman.

There's plenty of mathematical economics and non-mathematical economics. Mathematical economics is applied math that fits in this thread, while non-mathematical economics wouldn't fit. No different than numerology being non-mathematical playing with numbers not belonging here, while actual number theory does belong.

>>9071176
>correct definition
You can redefine whatever terms you want to convince yourself that your arguments 'win', but you might as well be redefining dogs as cats

>>9071180
>No different than numerology being non-mathematical playing with numbers not belonging here
Exactly! Just because something uses mathematics doesn't make it mathematics.
Mathematical economics [math] \neq [/math] mathematics.
Mathematical physics [math] \neq [/math] mathematics.
etc.

https://en.wikipedia.org/wiki/Definitions_of_mathematics
>The science of quantity
>The science of indirect measurement
>Mathematics is the science that draws necessary conclusions.
>All Mathematics is Symbolic Logic.
>Mathematics is mental activity which consists in carrying out, one after the other, those mental constructions which are inductive and effective.
>Mathematics is the manipulation of the meaningless symbols of a first-order language according to explicit, syntactical rules.
>Mathematics is the classification and study of all possible patterns.
>Mathematics is a broad-ranging field of study in which the properties and interactions of idealized objects are examined.
>The abstract science which investigates deductively the conclusions implicit in the elementary conceptions of spatial and numerical relations, and which includes as its main divisions geometry, arithmetic, and algebra.
>The study of the measurement, properties, and relationships of quantities and sets, using numbers and symbols.
>The science of structure, order, and relation that has evolved from elemental practices of counting, measuring, and describing the shapes of objects

>>9071186
You seem to have misread my post, I never claimed equality, you do realize \neq doesn't imply \not\subset right?

>>9071183
I haven't redefined anything. Go on, give me the """standard""" definition of mathematics that I've supposedly sidetracked with "my" own, for example here >>9070786

>>9071193
Replace "[math] \neq [/math]" with "[math] \not\subset [/math]" subset then.

>>9071194
>give me the """standard""" definition of mathematics
Why do you think one exists?

>>9071196
Then your post becomes incorrect,
see
>>9071180

>>9071116
I obviously meant to write 2 friends, we were 3 people total

>>9071194
>give me the """standard""" definition of mathematics that I've supposedly sidetracked with "my" own
see >>9071189

>>9071189
>The abstract science which investigates deductively the conclusions implicit in the elementary conceptions of spatial and numerical relations, and which includes as its main divisions geometry, arithmetic, and algebra.
>The study of the measurement, properties, and relationships of quantities and sets, using numbers and symbols.
>The science of structure, order, and relation that has evolved from elemental practices of counting, measuring, and describing the shapes of objects
Any one of these definitions implies "applied mathematics [math] \not\subset [/math] mathematics".

The rest of the "definitions" are rubbish.
>The science of quantity
This definition is too narrow. There are mathematical subjects that are not of a quantitative nature.
>The science of indirect measurement
This is both too narrow and too broad at the same time, as there are mathematical subjects that have nothing to do with measurement (direct or indirect) and at the same time there are non-mathematical subjects that deal with indirect measurements.
>Mathematics is the science that draws necessary conclusions.
Same as above, too broad and too narrow at the same time.

et cetera

>>9071204
What counts as a formal definition? Can I be defined by 'the person born in [specific hospital room] at [date and time of birth]'?

>>9071200
See >>9071204

>>9071197
Because people have a habit of inventing all sort of silly terms.

>>9071206
>Can I be defined by 'the person born in [specific hospital room] at [date and time of birth]'?
Yes. The universe is known to be deterministic so that would be enough to define you.

>>9071209
Why does 'the person born in [specific hospital room] at [date and time of birth]' have the essential property of existing in a material sense?

>>9071209
>The universe is known to be deterministic
source?

>>9071198
No, nothing of import changes. Mathematical economics is economics, not mathematics.

>>9071204
>This definition is too narrow. There are mathematical subjects that are not of a quantitative nature.
And there are mathematical subjects (in particular, applied mathematics) that are not about the study of mathematical structures, making your definition too narrow as well.

This >>9071209 is not me by the way. I already made myself clear, both ITT and in previous threads. The fact that you have no idea what a formal definition is, that's entirely your fault, and your fault only.

>>9071210
I couldn't care less about "why". That's "his" domain.
>>9071211
You might already be too indoctrinated to see it.

>>9071217
>The fact that you have no idea what a formal definition is, that's entirely your fault, and your fault only.
Define 'formal definition'.

>>9071221
Define 'define'.

>>9071215
I meant that in the sense that there are subdomains of mathematics that are not of a quantitative nature.
"Applied mathematics" is not a subdomain of mathematics.

>>9071220
>I couldn't care less about "why". That's "his" domain.
If 'the person born in [specific hospital room] at [date and time of birth]' does not have this essential property then it's still unclear that there exists an object whose essential properties are not exhausted by its formal definition, making >>9070786 ill-defined

>>9071225
That is for God to answer. I don't really care about it that much.

>>9071226
>That is for God to answer.
Answer what? There's no question in that post

>>9071220
>You might already be too indoctrinated to see it.
I asked for a source.

Personally I have no particularly strong opinion in either direction, so I believe that I would be able to look at your proof/source without too much bias.

>>9071225
It doesn't have the essential property of existing in a material sense because that could be a pointer to a fictional person. You actually existing, being made of atoms, eating, thinking, shitposting on 4chan with your imbecilic questions, none of these can follow from any formal definition of (you). You cannot create something by fiat.
Not so with abstract concepts which are created just so.

>>9071227
Answer as in "answer", not "answer a question".

>>9071230
>that could be a pointer to a fictional person
it could also be a pointer to some other guy born in the same hospital room at the same time

>>9071230
Define 'formal definition'.

>>9071229
Are you just pretending to be ignorant? Surely you must have suspected it.

>>9071237
Have your (you) and fuck off already.

>>9071238
>Are you just pretending to be ignorant?
No. In fact the exact opposite is the case.
I would like to hear your proof/source.

>Surely you must have suspected it.
It is at least a reasonable assumption about the universe, but I don't see something that would be convincing beyond any doubt.


And since you fail to provide anything but mild adhominems, I would say that you have no such proof. Since this discussion would be long over then.

>>9071239
Your definition of mathematics remains ill-defined based on the meaningless terms 'essential properties' and 'formal definition'.

>>9071217
>This >>9071209 is not me by the way. I already made myself clear, both ITT and in previous threads. The fact that you have no idea what a formal definition is, that's entirely your fault, and your fault only.

The fact that you have no idea what applied mathematics is, that's entirely your fault, and your fault only.

>>9071243
I know you're desperate to broaden the definition of mathematics into meaninglessness because you're mathematically illiterate. The typical brainlet mindset: everything must be brought down to his level.
But there's always an alternative: you can fuck right outta here and stop shitting up the thread.

>>9071246
If you can't even define your terms, please do not use them.

>>9071245
You may very well claim that, but it doesn't make it true. I know perfectly well what applied mathematics is. It is the application of results from mathematics in domains other than mathematics.
Which makes it's not mathematics.

>>9071247 (you)

How should I make my work simply unusable for physishits? They would like it as it currently is, but I want to somehow modify it.

>>9071251
> a mathematical structure as "an object whose ? are exhausted by its ?"

>>9071254
What is a "structure"? What is an "object"? Please define your terms before using them.

I'm reading Introductory mathematics by Geoff Smith, it's fun and pleasant to read

>>9071230
>It doesn't have the essential property of existing in a material sense because that could be a pointer to a fictional person.
Does 'the non-fictional person born in [specific hospital room] at [date and time of birth]' have this essential property?

>>9071259
What is a "property"?

>>9071256
>What is a "structure"? What is an "object"? Please define your terms before using them.
These are your terms, feel free to have a go at them.

>>9071257

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Can someone help me with this exercise?

>>9071260
>What is a "property"?
http://www.dictionary.com/browse/property

>>9071260
Define "These".
Define "are".
Define "your".
Define "terms".
Define ",".
Define "feel".
Define "free".
Define "to".
Define "have".
Define "a".
Define "go".
Define "at".
Define "them".

(Not even that guy by the way. You're retarded.)

>>9071267
What is a "dictionary"?

oops
>>9071269
for
>>9071261

What are dark numbers? Do they have something to do with elite numbers?

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>>9071257
I forgot the pic

>>9071266
Yes I can, but it would be completely pointless for me to tell you the solution.
So what have you got?

The direction [math] A \times C \subset B \times C \Rightarrow A \subset B[/math] should be quite easy if you think about the negations of both sides and what [math]\lnot A \subset B[/math] means.

>>9071272
It's a term coined by Wildberger for numbers we cannot know anything about or manipulate since it would be computationally impossible. He mentions these sort of things here https://www.youtube.com/watch?v=Lme-uNPrry8

>>9071279
I am learning how to prove things so I was thinking about something like

A x C subset eq of B x C then

A x C = { (x , y) | x € A and y € C }
B x C = { (u, v) | x € B and v € C }

I would use direct proof. Since sets of second members of tuples are equal. By assumption that A x B subset eq of B x C we have A subset eq of B.

This sounds kinda blurry and I know intiutively that statemant is true but is it valid proof of first implication? If not can you help me where I am doing it wrong

So if 'the non-fictional person born in [specific hospital room] at [date and time of birth]' has the essential property of existing in a material sense, unicorns are real?

>>9070820
>The claim that there exist objects whose essential properties are not exhausted by their formal definition is equivalent to the fact that the map of a territory is not the territory itself.
Is that a theorem?

>>9071296
>This sounds kinda blurry
That is also the problem I see.
>By assumption that A x C subset eq of B x C we have A subset eq of B.
I see no obvious reason why this would be true.

I would do it like this:
[math]x \in A, y \in C[/math] then we have [math](x,y)\in A \times C \Rightarrow (x,y) \in B \times C[/math] that is just the definition of what "subset" means.
[math](x,y) \in B \times C \Rightarrow x \in B, y \in C[/math] this is the definition of the [math]\times[/math]
So in conclusion: [math]x \in A \Rightarrow x \in B[/math] which means that [math]A \subset B[/math]

This is a bit drawn out to empathize what I am doing. You should always empathize clearness and separate your thinking into logical steps.

(Can you see why this does not work if A, B or C are empty?)

The other direction can be solved in a similar matter here you can start with [math](x,y) \in A \times C[/math] and then use the fact that [math]A\subset B[/math]. But the details are left to you.

How do I show that pullbacks and pushout(fibered product and sum) exist in category of abelian groups. There's no need in rigorous definition of these, just need to show they exist

I have come to doubt the existence of even most rational numbers.

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>>9071355

What are some good systems which refute the existence of "real" numbers?

>>9071361
>proving a negative
you're new to this aren't you

>>9071322
Cheers, it's much clearer now and I understand where I made mistake.

>>9071363
Is this some sort of new advanced bait?

>>9071363
Right and wrong. Those mathematicians that dislike the supposed "lack of rigor" in physics should also reject statements proven assuming generalized RH/CH.

>>9071355
What does it mean for a number to 'exist'?

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Summer once again lives up to its reputation.
>>9071266
Why is this not in the stupid questions thread? How dumb can you be to be unable to prove something that follows from the definition in a single line?
>>9071272
>>9071293
Just because we cannot directly manipulate a number doesn't mean we know nothing about it. Wildberger himself employs results obtained without directly manipulating numbers. His position is self-defeating since he's using arguments that depend on "manipulations" of infinities (like limits).
>>9071308
What part of "saying X exists as such and such does not mean that X does in fact exist as such and such" is so hard to understand, brainlet?

I have come to doubt the existence of even most integers.

>>9071389
>What part of "saying X exists as such and such does not mean that X does in fact exist as such and such" is so hard to understand, brainlet?
It's just a definition, based on the definition of essential property here
https://plato.stanford.edu/entries/essential-accidental/
>an essential property of an object is a property that it must have
this only means that [math] if [/math] 'the non-fictional person born in [specific hospital room] at [date and time of birth]' exists [math] then [/math] it exists in a material sense.

What axioms do I need to add to ZF to exhibit a counterexample to LEM?

I have come to doubt the existence of intelligent posters on /sci/

>>9071404
>I have come to doubt the existence of intelligent posters on /sci/
then fuck off already

>>9071407
No. I am king of the retards.

>>9071389
>Why is this not in the stupid questions thread? How dumb can you be to be unable to prove something that follows from the definition in a single line?
Does it really matter if I am posting in SQT or Math General? Are you autistic by any chance?

>>9071397
But it does not exist by virtue of being defined as such. You're also missing the fact that if some person is in fact born somewhere and at a certain time, those are not the only essential properties that it has. Those are just some essential properties that you'd find useful to refer to for whatever purpose. What if two persons were born at exactly the same place at exactly the same time?
"Exhausts" in that definition, by the way, does not refer to "being completely listed" but to "being drawn out completely", that is, as "the formal definition of X is the totality of what X is" as opposed to "the formal definition of X lists all the properties that X has".

>>9071397
>>9071412
>>>/lit/

>>9071412
Better phrasing:
"A mathematical structure is an object whose essential properties are exhausted by its formal definition" = "A mathematical structure is an object that is identical to its formal definition".
>>9071414
This pertains to the philosophy of mathematics, to what mathematics actually is, specifically. Nothing to do with /lit/.

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hi /mg/
I'm reading pic related. While I think it's a pretty book regarding most stuff (asides from the first 2 chapters), the hand-wavy treatment they give on the equivalence of turing machines (chapter 1) is making me a little bit upset. I've checked Sipser on TMs ( didn't check Hopcroft and Ulman on this, thought) and I've found his treatment unsatisfactory, close to that of Arora and Barak's. What I mean by this is that I think it lacks rigour as some proofs of equivalence of TMs by Sipser are similar to Arora anda Barak's claims, which are not proofs. From here, what I want to ask is if any of you guys know of any literature that have more rigour on treating TMs than both books I mentioned or if the proofs from Sipser are good enough and I'm just being picky.
Anyways, some proofs on complexity just come across to me as lacking something. Asides from what I asked, I also wanted to know if it's me who's wrong or if the proofs are indeed lacking something.
Thanks

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>>9071403
You can't because ZF is founded on classical first-order logic, where LEM is a tautology.
If you're determined to go down the route of constructivism, you'll probably find type theory a more suitable foundation than set theory.

>>9071116
19x3 = 57
that's how much the guy at the desk got, this includes the tip, without any tip he would have got 55 because of the discount. the remaining three dollars are the ones the guy at the desk gave you.

>>9071439
not him, but what does one need to understand homotopy type theory

>>9071443
Algebraic topology, homological algebra

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>>9071409
If wanting everything to be in its proper place makes me autistic, then yes, I am autistic. (Assuming autism is a biological trait, not a mental disorder.)
>>9071427
Why not just read the original papers?
Turing, "Computability and [math] \lambda [/math]-definability": http://www.turingarchive.org/browse.php/b/11
Kleene, "[math] \lambda [/math]-definability and Recursiveness": http://projecteuclid.org/euclid.dmj/1077489488 (sci-hub it)

>>9071439
But I need a theory in which the double negation of LEM is false as well.

>>9071539
>But I need a theory in which the double negation of LEM is false as well.
Elaborate.

>>9071551
You suggested type theory, but it proves the double negation of LEM.

>>9071557
[math]Intuitionistic[/math] type theory proves the double negation of LEM.
You can continue using type theory even with non-intuitionistic logics, just come up with your own unary operation on propositional types, call it "negation", and define logical operations and identities as necessary.

The cost of abandoning intuitionistic logic is that you'd be giving up certain natural interpretations such as Curry-Howard, so interpretation becomes a challenge (e.g., functions won't work the way you'd intuitively expect them to). But anyone who does something as unintuitive as breaking !!LEM would have a very good reason for why they're doing so, and it is that intuition that they'd use to interpret their type theory instead.

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>>9071663
Thank you, anon, I will look into it. My main goal is to create a system strong enough to prove the negation of LEM and AC.

If you want to get into constructive mathematics quickly, learn COQ and write down proofs in it.

>>9071750
The problem is that Coq without any additional axioms already proves the double negation of LEM.

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You're not an ailurophobe, right anon? You know what bring me joy?
The joy of cats: http://katmat.math.uni-bremen.de/acc/ (repost because mods are fags)

>>9071337
[math] f_1:G_1\rightarrow G [/math]
[math] f_2:G_2\rightarrow G [/math]
Pullback: [math] G_1 {\times}_G G_2 = \big\{ (g_1,g_2)\in G_1 \times G_2 \mid f_1(g_1) = f_2(g_2) \big\}[/math]

[math] f_1:G\rightarrow G_1 [/math]
[math] f_2:G\rightarrow G_2 [/math]
Pushout: [math] G_1 {\sqcup}_G G_2 = \cfrac{G_1 \oplus G_2}{\langle (f_1(g),-f_2(g))\mid g \in G \rangle} [/math]

Check that the diagrams commute and the constructions are universal.

>>9071752
yeah as intuitionnism does.

But then you can create your own formula type and try to create a special "demonstration theory" that fits your needs.

Let A,X formulas. Let T:= ((A\/(A->X))->X)->X.
Then T is a consequence of the modus ponens inference rule and the three following sets of axioms: (we assume right priority for parentheses)
P,Q,R are any sentences
T is obviously the double negation of LEM when T:= false

A1° P-> Q->P f
A2° (P->Q->R)-> (P->Q)-> P->R
A3° (P->R) -> (Q-> R) -> (P\/Q) -> R.

Indeed, A1° and A2° suffices to prove that X->Y is provable iff Y is provable under assumption X (deduction theorem).
So n order to prove T: it suffices to establishes:
(A\/(A->X))->X ⊦ X
But A;(A\/(A->X))->X ⊦ (A\/(A->X)) and so A;(A\/(A->X))->X ⊦ X and so (A\/(A->X))->X ⊦ (A->X) (i) (see deduction theorem)
as well, (A->X);(A\/(A->X))->X ⊦(A\/(A->X)) and so (A->X);(A\/(A->X))->X ⊦ X ; and so then (A\/(A->X))->X ⊦(A->X)->X (ii)
by (i) , (ii) axiom A3 we have (A\/(A->X))->X ⊦X and so by deduction theorem we get
⊦ ((A\/(A->X))->X )->X i.e ⊦ T.

In which degenerate logic do you work? (if either A1,A2,or A3, or modus ponens does not holds? )

>>9070786
>"Mathematics is the study of structures mathematically" is a perfectly satisfactory definition.
ftfy

>>9071804
>T is obviously the double negation of LEM when #T:= false#
I meant when "X is false" of course

Is there a name for a logic in which modus ponens does not hold in general?

>>9070010
desu mostly liked algebra but finally getting to stuff in geometry where I need some analytic concepts so...

going through books on analysis on manifolds to try to get more concrete examples of things like exterior algebras, etc.

Is 25-30 hours of study / week enough?

>>9072564
And don't be a gay elitist just tell me yes I'm gonna make it pls

>>9072566
25 hours might even be too much
try doing at most 3 hours a day for 6 days, and take a day off. you'll have better information retention. Even if you like studying, limit yourself to 3 hours. Trust me senpai.

>>9072584
This isn't what I've heard from professionals though? And yes I'm cherry picking. Of course I'd love to lower the amounts as I also work full time. I use Saturday and Sunday as catch up days and shoot for 5 hours / day mon-fri

>>9072591
Oh, also it's technically only 4 hours 10 minute cuz I use pomodoro technique (25 on, 5 off)

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why is it [math]\frac{-c + \mu}{\sigma}[/math] and not [math]\frac{c - \mu}{\sigma}[/math] ?

Or am I mistaken in comparing it to standardizing a distribution to the standard normal distribution? if so what is the difference ?

>>9072984
>>9072971
I think I see. So it determines the probability of deviations from a cost of 6 by centering and scaling it at 0, using a normal distribution?

and the cumulative function being decreasing (inverted?) is just the result of the cost being subtracted?

if that is pretty much it then I think I get it thanks.

>>9073040
Everything I said is wrong.

>>9073047
might I have misunderstood what you said and accidentally somewhat understood the model used?

It seems to desire to have a function that maps from cost to probability of buying, and a normal distribution centered on 6 for their example seems to achieve this?

(6 - cost)/SD falls around 0 when the cost is equal to the mean. Increasing cost deviates in the negative direction and similarly for decreasing cost.

The cumulative in that way is centered on the mean, though starts at 1.0 rather than 0.0 because of the subtracted cost.

(I assume logit does something similar but uses a different distribution)

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Would any analysts be able to assist me with this metric space problem? I'm having trouble proving that the metric is symmetric and that the triangle inequality holds.

>>9073040
>>9073065
Either move you ass back to >>>/r/eddit or stop hitting return after every new line.

>>9073098
it just so happened that my paragraphs ended up being like that, the spacing being a habit I have from tex

Is anyone in this thread working on protein structure?

I realize this is a NP hard problem but there are methods we have found that give PRETTY close approximations to what structure we want to build.

>>9073098
Either move your ass back to /pol/ or stop parroting retarded shit

>>9073091
It's trivially symmetric, you really should be able to get that yourself by writing definitions correctly.

For the other, you want to show d(x,z)/(1+d(x,z)) <= d(x,y)/(1+d(x,y)) + d(y,z)/(1+d(y,z)). Rewrite the right side as a single fraction, and then rewrite the whole inequality so it's no longer a fraction. Then try to simplify it to something you know is true.

>>9073111
Nice math post.

>>9073091
anyone worth their salt, not just
>analysts
should be able to do a basic metric space problem

Hey guys
Applied Math PHD here.
Anyone working on any interesting problems?

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>>9073091
I am assuming [math] d [/math] is a known distance, right? I'm feeling pretty content this morning so I'm going to help you out.
[math] \overline{d}(x,y) = \cfrac{d(x,y)}{1+d(x,y)} = \cfrac{d(y,x)}{1+d(y,x)} = \overline{d}(y,x) [/math] because [math] d(x,y) = d(y,x) [/math].
What you want to do for the triangle inequality is show that
[math] \cfrac{ \overline{d}(x,y) + \overline{d}(y,z)}{ \overline{d}(x,z)} \geq 1 [/math] (doing this >>9073142 will only get you running in circles).
So:
[math] \cfrac{ \frac{d(x,y)}{1+d(x,y)} + \frac{d(y,z)}{1+d(y,z)}}{ \frac{d(x,z)}{1+d(x,z)}} = \cfrac{d(x,y) \left( 1+d(y,z) \right) \left( 1+d(x,z) \right) + d(y,z) \left( 1+d(x,y) \right) \left( 1+d(x,z) \right) }{d(x,z) \left( 1+d(x,y) \right) \left( 1+d(y,z) \right)} [/math]
Let [math] \alpha = d(x,z) \left( 1+d(x,y) \right) \left( 1+d(y,z) \right) [/math]. We simplify the above fraction by [math] \alpha [/math] (which we can do since it is strictly positive) and show that the result can be written in the form [math] \alpha + \beta [/math] for some [math] \beta \geq 0 [/math], whereby our starting fraction is equal to [math] 1 + \frac{ \beta }{ \alpha } [/math] which proves the inequality.
Indeed,
[math] d(x,y) \left( 1+d(y,z) \right) \left( 1+d(x,z) \right) + d(y,z) \left( 1+d(x,y) \right) \left( 1+d(x,z) \right) = d(x,y) + d(y,z) + 2 d(x,y) d(y,z) + 2 d(x,y) d(y,z) d(x,z) + d(x,y) d(x,z) + d(y,z) d(x,z) = [/math]
[math] = d(x,y) + d(y,z) + 2 d(x,y) d(y,z) + d(x,y) d(y,z) d(x,z) + \alpha - d(x,z) [/math]
But [math] d(x,y) + d(y,z) \geq d(x,z) [/math] therefore
[math] \beta = d(x,y) + d(y,z) + 2 d(x,y) d(y,z) + d(x,y) d(y,z) d(x,z) - d(x,z) \geq 0\ \square [/math]

>>9073210
>simplify
multiply*

>>9073210
[eqn]\frac{d(x,y)}{1+d(x,y)} = 1 - \frac{1}{1 + d(x,y)}
\le 1 - \frac{1}{1 + d(x,z) + d(z,y)}
[/eqn]
[eqn]= \frac{d(x,z)+d(z,y)}{1 + d(x,z)+d(z,y)} =
\frac{d(x,z)}{1 + d(x,z)+d(z,y)} + \frac{d(z,y)}{1 + d(x,z)+d(z,y)}[/eqn]
[eqn] \le \frac{d(x,z)}{1+d(x,z)} + \frac{d(z,y)}{1 + d(z,y)}[/eqn]

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>>9073228
Very elegant solution.

>>9073236
A trick I learned way too late: the critical term [math]d(x,y)[/math] appears both in the numerator and denominator and that is hard to deal with. So we transform it so it appears only once, one could also write
[math] \frac{d(x,y)}{1+d(x,y)} = \frac{1}{\frac{1}{d(x,y)} + 1} [/math] and continue as above.

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At the moment studying discrete mathematics, logic, injection and surjections, and shit.

Also trying to figure out series.

Any resources where you guys could point me into?

>>9073433
Serge Lang Basic Mathematics.

>>9073433
There's always google for this kind of question: https://math.stackexchange.com/questions/1754954/any-good-books-for-infinite-series

>>9073486
>"infinite" series
No such thing.

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>>9073486
>infinite
>not -1
Brainlet detected.

[Spoiler] There are billion resources, that's for sure, but if somebody has already gone through them, and found something that is worthwhile, it will save time for everyone for him to post it here. Yes, I am assuming you're cis-male, and not an Apache. [/Spoiler]

>>9073541
what

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>>9073542
>what
what

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Is anyone interested in this anon's >>9071079 idea?
[math] \longleftarrow [/math]What about this number theory classic?
Are you still around anon?
(Pic fixed.)

>>9071980
It doesn't hold in non-normal modal logic for the strict conditional ([math]A,\square(A\rightarrow B)\nvDash B[/math]). I don't know off the top of my head of any weaker logics where it fails for the regular conditional, sorry.

do I need to do measure theory before the banach-tarski paradox becomes significant?

>>9071260
theft

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I'm trying to work on a procedural animation, but I need to get something moving in a superellipse based on an angle.
[eqn]x^8+y^8=1[/eqn]
Is it even possible to express this as a polar function?[eqn]r = f(\theta)[/eqn]

>>9073884
I've got a better idea:
1.- Pick a math topic (for example, diff geo, maybe something more concrete)
2.- Pick a textbook about said topic
3.- Edit that textbook onto an image of an anime girl lol

Why is math so popular? Isn't it for plebs?

>>9074297

Nice bait

>>9074301
Not bait. These threads are really popular. There should be many people who is studying math hard.

>>9074116
well i would try x = r cos(phi), y = r sin(phi)
->
r^8(cos^8 + sin^8) = 1
-> r = 1/(cos^8 + sin^8)^1/8

>>9074074
>>>/r/eddit/

>>9074356
why are you sending them to reddit?

>>9074362
Because that is where lesser beings such as himself belong.

>>9073884
I really want to stick my dick in her.

>>9074356
so you dont know?
i'll try asking there

>>9074322
That makes total sense in the most simple way.

You're a hero.

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From your experience, does listening to classical music help or hinder studying? Common sense says that playing classical music while reading, practicing, etc, distracts your brain, but I've seen a lot of shitters claiming it's helpful somehow.

>>9074446
I like to have distractions when I'm working on problems, but I usually use twitch streams for that. I personally cannot study new material while there's significant background noise going on though.
There's nothing special about classical music in this context; don't be a pseud and force yourself to listen to it because it's "intellectual music" or some stupid crap. If you legitimately like it and it makes learning more enjoyable for you it's probably going to improve your learning.

>>9074317
>These threads are really popular
These threads move quickly because of avatarfags circlejerking, not because of actual math content.

Is knowledge of calculus (not analysis), PDEs and linear algebra sufficient to jump into differential geometry?

>>9074532
If you don't know analysis your knowledge of pdes is superficial at best.

>>9074074
You don't need measure theory to prove it, but it's a good reason to believe we won't have a "good" measure which is defined for every subset of R^n.

>>9074074
The inconsistency of ZFC is a lot more significant.

Best linear algebra book?

>>9074446
>>9074519
In my mind, the pseud opinion is having to be in complete silence to focus on studying. I used to be of the opinion that classical music was complex and it took a lot of concentration to listen to and understand *properly* so you couldn't both listen to music and study because you're brain would be bettered focused on the single task you were trying to accomplish. For a long time I didn't listen to any music when I was studying or reading and felt good about myself that I was taking in more than the plebs with a shorter attention span. I gradually changed my mind about this.

I still hold the original view to some extent i.e. there are certain pieces of Bach with which I will not do anything else during other than just sit there and listen and try to follow all the various counterpoints; I also cannot study whist listening to any music with lyrics because the words distract me (I think this is probably the origin of classical music while studying meme) but there are some pieces of classical music that really genuinely help me study, but perhaps only because they make me calmer and put me in a sort of trance because I've heard them many times before and am very familiar with them. They make for a nice atmosphere: so the point is to put it on and ignore it rather than listening to the intricacies of the music, which I only find stuff I know really well. Also, it's not classical, but atmospheric music like Brian Eno's Music for Airports is something I listen to a fair amount whilst reading/studying.

Sorry for the big blogshit/ramble but I am quite drunk right now and couldn't come up with a more succinct way of articulating this. Basically, just use music while studying if and only if (haha) you find it helps.

>>9074588
Hoffman is my favorite.

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>>9074588
I used Linear Algebra, A Modern Introduction by Poole and found it adequate, but afaik it's not the best. Might be worth considering Strang, or as this anon says >>9074594 Hoffman is great as well.

Also, this textbook is great. I mean linear algebra, lie algebra, not much difference, right?

>>9074588
>>9074594
+1 for Hoffman and Kunze.

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Art Major
300k starting
Any job I want

Enjoy being unemployed math-faggots.

>>9074593

I think the common opinion (works for me as well) is that certain calming music can sometimes help you study even better as long as it's music that you have memorized.

>>9074519
Not him but it's true for me. I can study in a noisy environment relatively well (I still prefer having a quiet place though) except when that agitation is people talking around me or music I'm into (which is mostly classical). Garbage like muzak, traffic noise, construction noise, people talking in a language I don't understand, none of these bother me that much. That last one I think is a clue.

>>9074522
There's only two avatarfags, and one of them got so completely BTFO that he stopped posting on /sci/ entirely. The other is afraid to post because half the board knows who he is IRL and he risks getting pizzabombed if he's being too annoying.

>>9074919
>There's only two avatarfags
And both are/were students at University of British Columbia. More proof that Canadians are the Cancer that is killing 4chan.

If i do all of khan academy at what level will i be?

>>9075045
Video lectures only boost your confidence on the subject. It's no substitute for a book.

>>9071425
I hope you're not the same anon whose been wasting his time ranting about how applied math isn't math

>>9075045
Don't fall for Khan Academy meme if you want to be a pure mathematician. It is only good for high schoolers who don't give a shit about mathematics and want to have better marks

>>9074557
>a good reason to believe we won't have a "good" measure which is defined for every subset of R^n.
interesting
the only reason I ask is that the subsets described are dense but not complete in the unit sphere, so the resulting copy doesnt seem too farfetched yet
I will think about this

>>9075045
>>9075059
Video lectures can be a pretty good introduction. Khan academy is probably shit though.

>>9074936
>More proof that Canadians are the Cancer that is killing 4chan.
What exactly do you contribute?

>>9074919
>There's only two avatarfags
you must have trouble distinguishing anime females

>>9074919
>he risks getting pizzabombed if he's being too annoying.
don't most math students love pizza?

>>9075059
>>9075321
I can understand both sides of this, honestly. The 3Blue1Brown videos on Linear Algebra are actually really helpful, but obviously if you want to cement any knowledge in your head then use a textbook and practice examples.

>>9075326
I don't remember saying there is only one animeposter. The other guys don't avatarfag tho.

>>9075351
there's the avatarposter that uses those foxgirl pictures, and there's the avatarposter who uses hibike pictures

>>9075059
>Video lectures only boost your confidence on the subject. It's no substitute for a book.
If the video includes exercises then it's a substitute

Guys, I have a confession to make: I dropped out of a math degree 3 years ago. I started teaching myself math again recently and have been in these threads for a few months, but mostly lurking. I think I'm getting better now but I'm basically doing it as a hobby. I hope that's ok

>>9075354
>there's the avatarposter that uses those foxgirl pictures
That's the only anime avatarfag. There's more than one guy posting hibike pictures.

>>9075363
>That's the only anime avatarfag.
isn't there also the yukariposter?

>There's more than one guy posting hibike pictures.
then there's multiple hibike avatarposters

>>9075365
Wait, what's the difference between yukariposting and foxgirl posting?

>>9075368
>Wait, what's the difference between yukariposting and foxgirl posting?
Is yukari a foxgirl? I don't know the show, the foxgirl was some anime girl with fox ears

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>>9075379
Holoposter? (pic related)
That guy hasn't posted in weeks tho.

>>9075397
>Holoposter? (pic related)
maybe

>That guy hasn't posted in weeks tho.
i assume most people don't use avatars in every post, especially with all the banning lately

>>9074522
>These threads move quickly because of avatarfags circlejerking, not because of actual math content.
are we looking at the same thread?

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>>9075434
what is an avatarposter then? i usually post gorillas but have a few dozen posts ITT with no gorilla

>>9075438
>what is an avatarposter then?
Using an image or a set of images that would make your posts easily identifiable. No?

>>9075444
>Using an image or a set of images that would make your posts easily identifiable. No?
I guess the only thing is whether it's 'all posts' or 'some posts', if it's 'some posts' then posting hibike would make you an avatarposter

>which is a practice I can't stand myself
Why are you lying? You are an attention whore and the last part of your post confirms it.

>>9075434
>I'm only going to point these out because I object to your labelling me as an avatarfag
Your objection doesn't change the truth. Avatarfags (subhumans) such as yourself have no such power over this world.
>>9075438
>what is an avatarposter then?
You should make a "subreddit" and ask there instead. It's what all Canadian vermin should do.

>>9075466
>You should make a "subreddit" and ask there instead.
can you show me how, maybe set one up for me? i'm not familiar with the site

> It's what all Canadian vermin should do.
why the anti-canadianism?

>>9075468
>can you show me how
I wouldn't know. Your ilk should have a good """physical intuition"" for this.
>i'm not familiar with the site
Is that so?
>why the anti-canadianism?
I despise vermin.

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>>9075453
>>9075457
>>9075466
>tfw I was an avatarfag all along
B-but... how? I bet you wouldn't have known all those posts were made by the same girl (male) without me pointing it out. And that in general, not just ITT. I wasn't even using Hibike Euphonium reaction images predominantly when that guy started to spam the thread in a hissy fit a few weeks ago, and I bet his tantrum is the only reason why you even ended up painting me as a Hibikeposter.

>>9075489
>I bet you wouldn't have known all those posts were made by the same girl (male) without me pointing it out.
sure, but that goes for anyone posting with images who doesn't post the same themed image in every single post

>and I bet his tantrum is the only reason why you even ended up painting me as a Hibikeposter.
i just said there was someone posting hibike pictures, nothing to do with someone's tantrum

>I bet you wouldn't have known all those posts were made by the same girl (male) without me pointing it out.
If you aren't lying and they are truly your posts, I guessed more than half of the ones with images correctly without you pointing it out. And this isn't limited to the current thread. You should stick to text or at least learn to properly use your images.
>I bet his tantrum is the only reason why you even ended up painting me as a Hibikeposter
"hibikeposter" is just a name people can use to specify the vermin they are referring to. I personally don't distinguish the creature who is called "hibikeposter" from other kinds of avatarfags. They're all the same to me.

>>9075497
Oh, you weren't here when it happened? That's when the idea of an individual Hibikeposter existing became a thing as far as I know, when someone got triggered that I said I had already closed a certain academic chapter in my life in a post with a smug Reina, after which he proceeded to spam the the next couple /mg/s with Kumikos.

>>9075518
>That's when the idea of an individual Hibikeposter existing
Every single avatarfag might as well be the same "person" (if that word is even applicable here).

>>9075517
>I guessed more than half of the ones with images correctly without you pointing it out.
Ok. So assuming you're not full of shit: what tipped you off? (Whatever it is, it's unintentional, and I'm only asking so I can better mask my identity in the future.)

>>9075434
From that list of posts I wouldn't have assumed they were all the same poster. Don't see the problem here, honestly.

>>9075518
>Oh, you weren't here when it happened?
I was but I guess I didn't read the posts that closely

>That's when the idea of an individual Hibikeposter existing became a thing as far as I know
I just assume images being re-used in a general are probably being posted by the same person

>>9075524
>what tipped you off?
I don't really know, I can just tell when I see your posts with images.
>it's unintentional
Which is precisely why it will be hard for you to hide.

>>9070010
Heres a problem Ive ran into for my hobby.

I have a square. I dont know the dimensions of the square though.
In the square I have a point. I know the distance from each corner of the square to the point.
What I want to solve for is the position of the point.

Ive tried a few things but Im not able to cancel out L. I can find the point in terms of L from two adjacent corners. I feel as though L should cancel out since there should only be 1 possible position of the point given the 4 inner triangles.

How would you guys approach this? Been stuck for a day.

>>9075547
>What I want to solve for is the position of the point.
Meaning?

>>9075560
Trying to solve for the coordinates. In terms of (x,y).

I know that all 4 distances are needed for it to be solveable, so I tried to trilaterate for the 4 triangles, but I dont see how to get it to cancel out.

>>9075566
What coordinates mr. redditposter?

>>9075434
Only a complete redditor would link to every single post of his.

How do I keep myself motivated lads
Doing undergrad, forced to select shitty prerequisite courses. One of them is a REALLY shitty 1st year course, I had literally spent 3 hours making excel charts today. I am really start to question what am I doing there.

>>9075602
Realize that it's only a year or two of bs until nothing but math, in the mean time you can audit math classes or read textbooks so you can be ahead of the game

>>9075547
>>9075566
I still don't for the life of me get what "solving for the position of the point" is supposed to mean. Position of the point relative to what? "In terms of (x,y)" doesn't tell me anything. Where is the origin of this coordinates system? What are x and y supposed to represent? Where does your square lie in that plane? Do you know the coordinates of any of its vertices? Do you have any information that would allow you to deduce the coordinates of its vertices (at least as a function of the side length of the square)?
How can anyone give you tips when your problem is ill-posed?

>>9075575
At this point I cant tell if you are meming me. Not sure what you are confused about..
But I realized that the reason its solveable is not because the 4 distances from the corner are known, but because I know that its a square. I really didnt want to deal with trig but I guess I have to triangulate instead of trilaterate.
>>9075614
Its not ill-posted. You can make up any coordinates you want. If you are going to trilaterate its best to pick a corner to be the origin but you can do what ever you want. Since you dont know that you cant help me. Looking up trilaterate would probably help you understand what the question is about. I figured out what I needed to know though.

>>9075620
>meming me
Redditors aren't welcome here.

>>9075622
Ive never posted on reddit a day in my life. But sometimes I look at how useful this board is compared to reddit and I think twice about that.

>>9075620
>You can make up any coordinates you want.
No, you can't. Depending on the coordinate system you choose, your problem may or may not be solvable. If the coordinate system is centred at one of the vertices of the square with axes along its sides, you only need to know the distance to that vertex to calculate the coordinates of your point, for example. More general positions of the square can render your problem intractable.

>>9075627
>compared to reddit
So you are admitting to being a redditor. Glad we established that.

>>9075620
>Looking up trilaterate would probably help you understand what the question is about.
>posts in a math thread
>thinks people don't know what trilateration is
Once again: what is "solving for the position of the point" supposed to mean?

>>9075628
Its solveable from any coordinate system you choose.
>>9075642
I cant explain to you what a coordinate is.

>>9075644
You don't need to explain to me what a coordinate is. I seriously doubt you even know.
>Its solveable from any coordinate system you choose.
What exactly is supposed to be solvable from any coordinate system you choose? You still haven't actually stated your problem. The position of your point? Finding the side of the square (doubtful, as you don't even need a coordinate system for that)?

>>9075648
From any euclidean coordinate system you choose you can solve for position. I really dont feel like explaining to you how a coordinate system is arbitrary.

>>9075642
>Once again: what is "solving for the position of the point" supposed to mean?
is /mg/ a thread for high schoolers now?

>>9075663
>euclidean coordinate system
oh so its euclidean now?
I think you could benefit from thinking about what question you wanted to ask

>>9075669
>euclidean
I dont know if it needs to be. But I know its solveable if it is. The question is straight forward. You just dont know how to answer it. Its more embarrassing listening to you ask what the position of a point means then anything else.

>>9075644
>>9075663
>Its solveable from any coordinate system you choose.
Oh really?
"Let [math] \big\{ (x_1,y_1), (x_2,y_2), (x_3, y_3), (x_4, y_4) \big\} [/math] be the unknown coordinates of a square in the euclidean plane and let [math] P = (x,y) [/math] be a point in its interior at distances [math] d_1,\ d_2,\ d_3,\ d_4 [/math] from the vertices [math] (x_1,y_1),\ (x_2,y_2),\ (x_3, y_3),\ \text{and}\ (x_4, y_4) [/math], respectively.
What are the point's coordinates?"

If you prove that the above problem is solvable I will chop off my dick and send it to you in a box along with 100 billion dollars.

>>9075678
Its literally called triangulation. You have to know an angle, in this case 90 degrees.

>>9075665
It's definitely not a thread for ill-posed problems and stupid questions. Shouldn't be, at least. Yet here we are, with an idiot who doesn't even know what problem it is that he wants to solve.

>>9075686
>doesnt know what "solving for the position of the point"
>calls others idiots
The irony

>>9075685
I know what trilateration means much better than you will in a million years if all you did all day every day was study what a trilateration is.
You want to find the position of your point relative to what?

>>9075688
If you're not the guy who posted the "problem", I hope you're baiting.

>>9075686
>with an idiot who doesn't even know what problem it is that he wants to solve.
You must be talking about yourself, everyone else understands what the problem is

>>9075694
>everyone else understands what the problem is
Yeah? Explain it to me then.

>>9075696
What part of it do you not understand?

>>9075691
>trilateration
I see you don't know what that is if you think its triangulation.
> point relative
I don't understand how you cannot seem to grasp that you can choose your origin to be anywhere and the problem is solveable
>>9075694
He understands it. He couldn't figure out how to solve it so he is pretending to not get it. I used to do this when I was younger and couldn't admit I didn't know something.

>>9075698
>you can choose your origin to be anywhere and the problem is solveable
Prove it. 100 billion USD await you if you succeed.

>>9075697
Let's say, all of it. Explain what the problem entails.

>>9075701
You have a triangle with 3 sides and the location of 2 vertices known. Are you really going to bet 100 billion on whether or not the third vertex can be found.

>>9075708
>You have a triangle with 3 sides and the location of 2 vertices known.
Except you don't know the location of any of its vertices. All you know is the length of two of its sides.

>>9075711
Its a square of dimension L. Try not to overcomplicate it mate.

>>9075673
im not the guy you were arguing with
have you tried using high school trig

>>9075712
The dimension, L, is unknown, remember? That's why you were trying to get rid of it from whatever calculations you were attempting to do.
I'm not complicating anything here. The only thing I'm doing is pointing out is that you have no clue what problem it is that you want to solve, and say stupid shit like "it's solvable for any coordinate system".

>>9075714
when I asked the question I was trying to avoid trig because I thought it was unneeded. Ive realized that was a mistake on my part because a rhombus could be created from those distances as well creating multiple solutions. The fact that its a square so there are 90 degree angles was the info I was missing.
>>9075717
Please stop embarrassing yourself.

>>9075702
>Let's say, all of it. Explain what the problem entails.
If you don't understand any of it then there's a much bigger issue at play here.

>>9075720
You're the only one embarrassing himself, brainlet.

>>9075717
>The only thing I'm doing is pointing out is that you have no clue what problem it is that you want to solve
speak for yourself

>>9075721
>>9075726
Your (you)s are to be found here: >>9075693

>>9075728
The cure to your mathematical ignorance/confusion can be found here:
>middle/high school math classes

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>>9075731

>>9075737
I sincerely hope someone posting in a math general who can't understand an elementary geometry set-up is just pretending to be retarded, my 13 year old problem probably understands it better than you (pretend to)

>>9075754
13 year old brother*

p.s. someone make a new thread

>>9075754
>>9075757
Fuck off, shit-for-brains.

>>9075754
Prove this >>9075678 is solvable. It's elementary, right, brainlet?