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3:00 PM
Wait, as for the case r=\sqrt{2} +\sqrt{3}. We can rearrange that polynomial and multiply both sides by r to get an identity.
 
ugh, yes.
 
Maybe it really is all algebraic numbers, then.
 
but how do you get rid of the constants -10 and 1?
 
And the false identification of measurement with 'telekinesis', so to speak. @secret
I'm not sure that's separate from what you said, though.
 
By writing x*10 as x+x+x+x+x+x+x+x+x+x.
 
3:04 PM
'Consciousness causes collapse' interpretations irritate the hell out of me.
 
This case becomes a hot topic recently as a news programme in HK just used a toy turtle to debunk animal telepathy as either delussion or scam

Well... measurement on one of the entangled states will always project it into some product state (as long it is not a bell measurement), thus establishing the nonlocal correlation (under many quantum interpretations), thus it does contain the "nonlocal" element which can be easily mistaken
 
Yeah. Nonlocal correlations are a thing, but nonlocal signaling isn't
 
@user107952 Ah, in that case, then you will take care of all the constants, and since every algebraic number is computable and uniquely identified by its minimal polynomial, then you have the identities, always
 
ehem, Mathematics chat guys :P
 
though I must admit that x+x+x+x+x+x+x+x+x+x is very clumpsy
@GFauxPas Maths chat is currently in a superposition of physics and maths, deal with it : )
 
3:06 PM
D:<
 
besides, there's a universal algebra discussion ongoing, so it is fine
 
How one interprets those correlations is a question worth asking. But one certainly doesn't have nonlocal signalling.
@GFauxPas Eh, see today's XKCD which I linked earlier in the transcript.
 
i was just joking
 
are magnets that hard to understand tho
 
3:08 PM
A bit, yes.
Or at least, they're not as basic as basic physics.
 
Acuriousmind and emilo pisanty in h bar can go forever on the intricates of each interpretation

But yeah, no communucation theorem said no, each party when they look at their own measurement outcomes, they just see random distributions, the correlation is only clear after they get together and compare the results
 
Wonder where gravity would fit on that graph.
 
@SteamyRoot Eh, I'd classify that under general relativity.
 
unless, it is quantum gravity, which should be well inside the danger zone beyond quantum mechanics
 
definitely
I think QFT would be on the danger boundary as well, but to the right of GR
Both require heavy lifting, but at least the math for GR is well-known and settled.
 
3:11 PM
Now, the only question is how many equations are needed to minimally generate the identities for particular algebraic numbers. My suspicion is that besides the commutative, associative, and distributive properties, you only need one identity, except for 0, where you need two.
 
I think one for each algebraic number is enough, since every algebraic number can be uniquely defined by its minimal polynomial
 
What about 0 itself?
 
It's just Maxwell's eqns though @Semiclassical , that's Physics II
so I guess not Physics I and I guess you need Calc III
 
and your way of writing it ensures all constants ca be eliminated

As for zero, I am not sure how to calculate its minimal polynomial...
 
It's not just Maxwell's eqns. It's also how materials give rise to magnetism.
 
3:13 PM
Well, for 0, it is just x.
 
Maxwell's equations don't tell you why certain materials are paramagnetic versus diamagnetic, for instance.
 
oh
 
And Maxwell's equations as done in first year physics typically don't talk about the magnetic H-field, and if you're doing permanent magnets that's essential.
 
I dont know about the magnetic H-field :(
so I guess I don't "get" magnets after all
thanks for ruining my day Semi
 
Basically, it's the magnetic field due to external free currents
 
3:15 PM
cf to currents running in a circuit?
 
sure, that'd be one.
 
The notion of quantum fields permeating all of spacetime is very very dangerously close to the concept of chakras and other esoteric energy related topics since they both have this "everywhere and everything as part of one thing" property

I am still learning QFT thus I am not confident in not mixing them up (except as always, no nonlocal signalling)
 
the magnetization field M, by contrast, is the field generated by the material in response to an external field.
And the magnetic field B is the combination of those two.
 
we just worked with B
 
@user107952 In that case, I think then 0 being apparently an exception is because x+0=x and x0=0 has nothing to do with the algebraicness of 0 (those two identities are part of the rings, and actually, under the ring axioms, x0=0 is a theorem)
 
3:17 PM
Yeah, that's typical.
 
similar to how 2 has $x+x=2x$
 
It's also reasonable if you're not doing materials, since there's no material to respond to.
hence there's no magnetization field and B=H up to a proportionality constant
 
ah
 
(similar story with dielectric response to electric fields, though this usually gets touched on in intro physics w/r/t capacitors)
(i.e. why inserting a dielectric medium into a capacitor increases its capacitance)
 
I think you still do need x*0=0. Because there is no subtraction or additive inverse in the signature, and you need those to derive x*0=0 from the ring axioms.
 
3:20 PM
intro physics typically excludes another bit as well. How does an electron respond to an applied magnetic field?
The intro physics answer would be to cite the Lorentz force, and that's certainly there.
 
@user107952 But you said you have negative elements, thus we should expect a variable (forgot the correct term in universal algebra) $x+(-x)=0$ (this is a ring axiom, the existence of additive inverse) that will give you the pathway to derive $x0=0$
 
But the electron also has an intrinsic dipole moment. this doesn't matter for constant magnetic fields, but it matters a lot for magnetic field gradients.
and this loops back to magnets, because one thing that gets drilled into people in intro physics is that the Lorentz force can never do work.
and yet I can use one magnet to push another along a table.
the point is that the magnetic field is not doing work by virtue of the charges of the constituents in the material, but rather by virtue of the collective magnetic moment
 
(and really, you only need one additive inverse to complete the proof of the theorem x0=0, which is why it is very very hard to divide by zero (my personal project of a year ago))
 
blah blah blah
 
@Secret Well, this is a pure universal algebra question, no existence statements allowed, only universally quantified equations. If there is a single identity that implies and is implied by both x+0=x and x*0=0 under the commutative, associative, and distributive properties, I would love to hear it.
 
3:27 PM
Let me just double check your structure, so you are actually not working with a ring because there is no - in the signature?
 
Yes, no subtraction or additive inverse.
 
Ah I see, in that case, yes, you will need x0=0 as a separate axiom. (And from the looks of it, you seemed to be working with a semiring)
Right, so in conclusion your structure will consists of the semiring axioms as the identities, plus one identity (the minimal polynomial of r, rearranged so that there are no constants and no - signs)
anything else should be theorems, including the fact that 2 generates the ideal of even numbers
 
This could make a nice undergraduate research project, my universal algebra and model theory questions.
I am only an undergraduate.
 
looks good. Model theory is also very cool as you seek structures that satisfy a set of logical statements under some formal language. That should train you more on seeking for identities in constructing structures
(I should also made a note on including minimal polynomials just in case I need to include algebraic numbers in any structures I am constructing that need them)
 
0
Q: Showing Abel Means of a Fourier Series Converge Uniformaly to $f$?

ZophikelIn the text "Fourier Analysis and Related Topics", i'm having trouble proving the following Theorem in $(3.5.5)$ utilizing Fourier Methods/Summability Methods. Also i'm not sure how to approach $(ii)$ with the use of Summability methods may I have some hints please ? $$\text{Theorem} \, (3.35)$$...

 
4:38 PM
@Secret Not sure if you know this already, but:
A puzzle: Write "$x$ is nonnegative" in the language $(0,1,+,\times)$ where the model is $\Bbb Z$
I'm not sure if that's the right way to say that
But you can write something like $\exists a:a^2=x$ for "$x$ is a square" and stuff
and if $>$ were in your language, you could do like $x+1>0$
But it's not
(Note that this is essentially equivalent to asking for a way to write "$x$ is greater than $y$" in this language)
 
.....
 
@AkivaWeinberger uh, why we cannot write $x+1 > 0$? That defines all nonegative x?
 
@Secret because your exercise is to express $>$ in the language
and because $>$ is not in your language
 
ah right
 
Ignore that
 
4:50 PM
I'm very curious as to what it says
 
btw, here's last night dream in pictures:
Algebraically speaking, the brown room complex on the far right should not exists, but it does because there's a string of f(x) that don't commute, hence making it unique somewhat
and my guess on the possible thing that inspired this dream might be this discussion:
23 hours ago, by Tobias Kildetoft
@shaihorowitz just take 1011011101111011111...
23 hours ago, by Akiva Weinberger
There is no spot omega.
 
@AkivaWeinberger Ooh, a puzzle!
 
5:17 PM
@Secret To be clear, you can use logical symbols like $\land,\lor,\lnot,\forall,\exists$
 
yup, that's part of the 1st order logic which is always included in a formal language
 
Hm, I think I might have a solution but I'm not sure I'm using only admissible things
Probably not, since I'm basically trying to do induction
 
You can't use sets or symbols like $\subseteq$ or $\in$, though
 
I'm not. I'm just posting it because I don't think that works, can I say "$n$ is positive if $n=1$ or if $n=m+1$ with $m$ positive" or is this kind of recursion not formalizable in this language?
 
I don't think it is
Or, rather,
that's technically true if you define "positive" to mean "integer", isn't it?
$n$ is an integer if it equals $1$ or is one more than an integer
So it doesn't look like it uniquely defines the notion of positive
Also I don't know how you'd write that in the language
 
5:34 PM
Indeed, good point
 
Oops!
 
Here comes Balarka killing mosquitos with cannons
 
lel
 
Oh. Wait, that was the intended solution? lol nvm
 
5:36 PM
I was thinking of squares and then it dawned on me
 
Dammit!
 
That's a very very kewl puzzle, man
 
Hopefully Secret didn't see that!
 
Nice on though, I knew the relevant theorem but didn't make the connection
 
I got a over 9000 ego boost right now
what am I going to do with the extra ego?
 
5:37 PM
You had me convinced you had seen the puzzle before, to be honest
 
I hadn't!
 
Sell it on the black market
 
What's the ego exchange rate now?
 
Send me some ego, I have self-hatred problems ;-; . My account is negative :(.
 
I think it would be very expensive if it were a tradeable good
 
5:39 PM
@Mann Well, I don't have a egopal account, but I can recommend you a good movie
 
What movie?
 
Oh shit, let me think up a soul-crushing self-diminishing movie real quick
 
@Secret are you here?
 
Busy entangling stuff in the h bar
 
it's fongbong today... just so you know
7 hours till the decision of my fate
 
5:47 PM
Hope for the best :)
 
@Justwinbaby thanks
 
Personally, I always "expect the worst."
But that's just me.
I don't like being disappointed.
 
@AkivaWeinberger Can I write the primes? I can write a specific class of them by a similar technique, but can I write all of them?
 
@BalarkaSen Uh, "For every pair of numbers that multiply to $x$, at least one of them equals $1$ or $-1$"
 
Ah, I was thinking too hard.
 
5:55 PM
"…and $x$ is positive (using your solution to the last thing)"
 
My life is a soul-crushing self-diminishing movie xD
 
Has Huy disappeared again?
 
This thing (which is being released daily in parts it looks like) is cool, for anyone interested
Premise: Humanity becomes immortal in the early 21st century (no deaths, no births). It's now the year 17,776.
 
wtf? Was that a virus?
 
Nobody knows
 
6:01 PM
24 mins ago, by Balarka Sen
I was thinking of squares and then it dawned on me
squares... having no idea so far
the positive and the negative numbers are quite symmetrical if you consider the squares
oh my god
 
Like, if you were modelling on $\Bbb R$, then $\exists a: a^2 = x$ would suffice.
 
shocked to see DogAteMy yet again
 
That's what I had in mind.
 
hi, Balarka'
 
Bingo @Leaky
 
6:02 PM
Hi @Ted
 
that's cool
 
Hi @TedShifrin
 
heya @Alessandro — any casualties? :P
 
really a cannon
 
Right? I was pleasantly surprised.
 
6:02 PM
@AkivaWeinberger is that the intended solution?
 
@AkivaW I have sent this problem to Soham
 
@LeakyNun What? I missed it
 
@AkivaWeinberger Balarka said Bingo so I suppose it's the same solution
@BalarkaSen is it the same?
 
yeah
 
Oh nice
 
6:03 PM
is it the intended solution? @AkivaWeinberger
 
Not yet @Ted, I'm working on it
 
Well, I know you try.
@Alessandro: That guy with the right-continuous question then wanted to know if your original right-continuous function on the closed set $A$ is monotone increasing, can one assert existence of a right-continuous monotone increasing extension to $\Bbb R$.
 
@LeakyNun you have give all your best, and your maths is good, I think you will be fine
 
@Secret lol thanks
 
@LeakyNun Yeah
 
6:06 PM
@AkivaWeinberger that's... crazy
 
There's a cool proof of that theorem via quaternions
 
half-integer quaternions I think
 
oh, 4 square theorem? yeah.
 
Yeah I forgot how that works
 
or whatever that is called
 
6:07 PM
Oh, the half-integer quaternions form a 24-cell lattice in 4D space I think
Fun fact (assuming I didn't miswrite it)
The 24-cell is the "extra" Platonic solid you get in 4D
 
Hi Professor.
 
@AkivaW I am reading that thing. I have no idea what's going on.
Is the red guy communicating with an alien or something?
 
I think they're actually called Hurwitz quaternions but don't quote me on that
 
@BalarkaSen It will make sense if you keep reading
 
6:09 PM
@TedShifrin I'd guess that the answer is yes since closed sets are rather nice, but I'm having troubles thinking of a right continuous function on the Cantor set
 
Yeah you don't actually know what's going on for most of the first chapter
 
What about the usual Cantor function, @Alessandro? Isn't it only one-sided continuous?
 
I guess the premise is technically a "spoiler" in some sense then idk
 
I've forgotten.
I see that DogAteMy is pretending not to be here by ignoring me :D
 
I think it is continuous but I'm not sure
 
6:11 PM
Yeah, it's continuous.
I'm being dopey.
 
Under what condition a totally disconnected space be zero dimensional?
 
pretends not to respond
 
@Mann What sort of dimension do you mean?
 
hi Tobias
 
They all agree for nice things I think @TobiasKildetoft
I forget what nice means here though
 
6:12 PM
@TedShifrin Hi
 
A nice space is one that rewards cooperation rather than exploiting it
 
The definition of zero-dimension here would be just - If there exists a basis for the topology consisting of clopen sets only.
 
So $\Bbb Q$ for example?
Are there any totally disconnected sets that aren't zero dimensional?
 
Just discovered this
 
I think "totally disconnected+$T_0$" is enough to get a basis of clopen sets
 
6:15 PM
That's what i am wondering kind of.
@AkivaWeinberger
 
I am on -48C now.
I have even less idea of what's going on
 
Oh crap which one is $T_0$
 
but this is trippy shit
 
No doubt
 
Oh, I misremembered, $T_0$+basis of clopen sets implies totally disconnected
 
6:18 PM
That was the one i just proved, i was checking if there is something in the inverse implication too.
 
Search for "totally disconnected+~zero dimensional" here
 
Also the end of that chapter, as well as like chapter 3 and a few others, are in the format of YouTube videos
 
A zero dimensional $T_0$ space is hausdorff and then further a zero dimensional hausdorff space is totally disconnected,
 
There's only a small chance you're gonna miss that but I just wanted to mention it in case you skip it by accident
 
@AkivaWeinberger That's Jon Bois, the funniest and most recent sportswriter you've read
 
6:19 PM
This is getting trippier every second
 
Big big fan of the Tim Tebow CFL chronicles
Strongly suggest it
 
I already love that site @AlessandroCodenotti <3
now
 
@MikeMiller Not a large crowd, to be honest
Sportswriters I've read
In fact I'm not even sure what a sportswriter is. Writes about games? Writes fiction in which sports is a major plot element? What?
Probably the second thing
 
I am a busy person tonight: splitting my attention between reading quantum papers, to checking my chemistry calculations and checking the maths chat
 
@Mann if you prefer paper over screen you should get a copy of "counterexamples in topology" for that kind of things
 
6:24 PM
@AkivaWeinberger any more puzzle in that language?
 
Nah
I mean I'm sure they exist
But none that I know of
 
@AlessandroCodenotti , thanks I will try that. Though i am really new to this. I need a lot of practice. :|
 
Huh. So it's about some weird sports with twisters in outerspace or what
 
I think it's provable you can't define $\Bbb R$ in $\Bbb C$ with just the language of fields
@BalarkaSen No the sports is on earth
I mean the images show maps of Nebraska and adjacent states
 
@AkivaWeinberger heh?
you mean $(0,1,+,\times)$?
 
6:26 PM
Yeah. But I might be wrong
 
interesting, let me think about it
 
@BalarkaSen But you saw the intro at the end of Chapter 1 was a YouTube video
 
That's suppose to be SB nation, right?
 
Ah, ok
 
Yeah @Justwinbaby
 
6:28 PM
I am listening to the "What is this" video now
Ok, I got it now
I have been skipping the earth-talks mostly :P
 
Seems like i found the property i was looking for but need to prove it.
"A locally compact Hausdorff space is zero-dimensional if and only if it is totally disconnected."
 
What does locally compact mean again?
 
Every point has a compact neighborhood
btw hai
 
R would be a simple example, that was the original question in the book.
 
Hi @Daminark
 
6:39 PM
@BalarkaSen The what?
 
@Daminark yeah, sometimes locally X means "every point has a nbhd which is X", sometimes it means " every points has a local basis of sets which are X"
 
@akivaweinberger the chapters where earth people talk to each other
 
as opposed to the spacepods
or satellites or whatever
 
Compact neighborhood i think.
 
6:41 PM
I mean I dunno if that's a good idea but whatever
 
Ah @Alessandro, makes sense
 
This is a real interesting space here though, o.o
https://topology.jdabbs.com/spaces?q=%20Totally%20Disconnected%20%2B~%20Zero%20Dimensional%20%2B%20%24T_6%24%20%2B%20Second%20Countable%20
 
"Cantor's Teepee is Cantor's Leaky Tent with the apex removed" lol those are some interesting names
 
There's a blog on it, I loved the starting picture. xD
https://blogs.scientificamerican.com/roots-of-unity/a-few-of-my-favorite-spaces-cantor-s-leaky-tent/
 
The starting picture isn't loading for me :(
 
@AlessandroCodenotti che?
 
it's a pity the blog post doesn't explain more precisely what are the big differences between the leaky tent and the leakier tent
 
These names are amazing omg :D
 
If you want another mind bending space to think about look up the hawaiian earring, its fundamental group specifically
 
@Semiclassical i hope you remember me, good news! my university admission test results has been announced. i probably can get into galatasaray uni. dep of maths.i am so happy. i wanted to share my feelings.
 

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