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3:00 PM
isn't psij going to also be pretty close to psii ?
 
To see that you have to form the tensor product of the irreps for the states and the operatir
no
that will normally differ strongly, much stronger than the energy
 
okay
 
You get for example "new nodal planes"
 
but psii and psij are eigenvalues of H0hat
 
eigenfunctions!
 
3:01 PM
oh yeah
sorry
 
but yes of H_0
so for that we can classify them by their symmetry
 
not of H1, and so far you have not said anything about H1
in order to get that <psii|H1|psij>
 
and thanks to the tables we can classify the operators as well
 
like
 
we have all the rotations (angular moments, momentum, and polynomials
 
3:02 PM
the group acts on H1 like this representation ?
 
Does maybe someone of you have an idea about my question:
0
Q: The vector $s$ spans the solution space

Mary StarFor a field $K$ and $1<n\in \mathbb{N}$ let $A\in K^{(n-1)\times n}$ aa matrix with rank $n-1$. For a row vector $z\in K^{1\times n}$ let $\left (\frac{A}{z}\right )\in K^{n\times n}$ be the matrix that we get if we add as the $n$-th row of the matrix $A$ the vector $z$. To show that there is a...

?
 
using those we can see for all important physical operators how the group
well the magnetic field is basically a rotation by symmetry
while the electric field is a translation
by symmetry
for example if UV light shines on your skin
 
angular momentum rather than momentum you mean ?
 
then the color molecules in your skin will adopt most likely a wavefunctiion with one more nodel plane
@mercio angular momentum for magnetic field
 
yes
 
3:05 PM
@mercio and momentum for electric field
 
I can't say yes again
the chat thinks i am spamming
 
thats why we say "dipole" transition. :-)
for electric fields, and thats why dipoles are important as well
 
so H1 is pretty much angular momentum operator ?
 
yes (for a magnetic perurbation)
 
yeah
 
3:07 PM
So it means some classes of symmetry breaking molecules are especially susceptible for magnetic response.
(the ones where Rotz is in E^2)
((and not the ones where Roz is in a T))
 
but if it's in a T isn't it very suscepible to symmetry breaking
 
yes exactly!
 
so the molecule will distort
 
But for some reason its the by far rarer cases.
But still for a T case we don't know by symmetry alone what will happen.
 
and if it's an E² what happens ?
 
3:11 PM
I mean what symmetry braking, level splitting exactly will take place.,
It is "paramagnetic".
at least after distortion
by symmetry.
 
the molecule itself will be moved by the magnetic field but it won't distort ?
 
And these E cases are ring shaped molecules
@mercio No no
 
aw
the electrons can make turns in those rings then ?
 
The molecule is bound to distort
 
won't the ring align with the magnetic field ?
 
3:13 PM
@mercio they do
funnily
Especially in the Bohmian mechanics picture
These molecules stustain ring currents in the magnetic field.
@mercio Well yes, but thats complicated and something different.
 
aw :(
 
The electrons in the first instance react much faster than the nuclei
 
ah
 
thats the reason we can use the nuclear positions
as parameters in the Hamiltonian
Its in the first instance physically disconnected effects
But from our joint study we saw that they are related by symmetry principles.
So normally you look at the "rigid" molecule. Then you think about what happens in some field eg.
Considering nuclear rearrangements or distortions is a different thing.
 
okay
 
3:19 PM
To make the connection we did is the new thing so to say.
 
and you were interested in the angular momentum because you put things in a magnetic field
 
Although people observed that the phenomena are related, there are even terms for it.
@mercio Yes. Part of my research is magnetic response of molecules.
 
I see so it's good news that you could identify that Rotz had to be a special irrep when things split
 
Its perfect! Its actually a great day for me, and all because of your efforts!!
 
:s
 
3:22 PM
i need to wirte that up soon. And my plan is to submitt to Science .
And I will need your help for that
 
:o
there will be one half of the paper written in chemistry language
the other half written in maths language
 
Thats great!
 
x)
 
I am afraid that most of the technical parts will end in the supplementary anyway.
Thats the drawback with that kind of journal.
Maybe before I also have to do something else now. I just give you a link to the concept we actually understand now its called "anti-aromaticity" and I think now its more basic than aromaticity and that its the first time it is really understood now.
This is from the "gold book" of defintions of chemical terms: goldbook.iupac.org/html/A/AT06987.html
Here you can read in the very short the phenomenological definition of anti-aromaticity.
 
i'm not sure I'm understanding much of it lol
 
3:29 PM
And you might get some idea how these properties which appear at first sight unrelated seem to have a deeper relation by symmetry.
 
yes
 
" and display tendency to alternation of bond lengths and fluxional behavior (see fluxional molecules) both in solution and in the solid. Antiaromatic molecules possess negative (or very low positive) values of resonance energy and a small energy gap between their highest occupied and lowest unoccupied molecular orbitals. In antiaromatic molecules, an external magnetic field induces a paramagnetic electron current."
thats the part were we come into play. Tendency to distortion is that Jahn-Teller stuff, the energy gap you might get as well and the paramagnetic current is exactly the type of magnetic repsonse we were talking about all along
 
I probably have to take a break
 
Me too, actually until tomorrow! Thank you very very much. I hope you are interested to continue that a bit!
 
rushes to his QM book
 
3:32 PM
:-)
Cheers to all
 
4:06 PM
[Random]
Let associator $(,,) : M \mapsto M$
Let Classes: RRR,RRL,RLR,RLL be e.g. LLL -> x0=0,x1=x,xq
(1,x,y)
RRR: =id RRL: =id RLR: =1. RLL: =1.
(x,1,y)
 
@rschwieb scheena dog
 
$RRR: =.1. RRL: =.1. RLR: =(.1.)^{\leftarrow} RLL: =(.1.)^{\leftarrow} $
(x,y,1)
$RRR: =(.1)^{\leftarrow} RRL: =(.1)^{\leftarrow} RLR: =id RLL: =id$
sure, associators will capture everything in a nonassociative magma, but the different kinds of maps of "multiplication by 1" is making things very confusing. I guess I need more robust identities
It is said that any associator behaviour can be determined by the forms
(a,b,(c,d,e)), (a,(b,c,d),e), ((a,b,c),d,e)
I think this will be easier if we are working with nonassociative rings, because in those, associators have a nice form of (a,b,c)=(ab)c-a(bc)
 
4:24 PM
@LeakyNun Come again?
 
@rschwieb good day
 
haha
hi
 
schönen Tag
 
that was sufficiently far from languages I know to not be recognizable to em
guten tag
 
Bavarian
 
4:25 PM
Lately I've been adding to the Properties pages
namely, "If you want to learn about X, go read these books/articles"
 
nice
 
I figure that gives a lot of bang for the effort spent: ringtheory.herokuapp.com/properties/property/19
There are a lot of screwy ring types and it would help a lot to have a list of surveys on the one you're interested in
@LeakyNun What have you been keeping busy with?
 
not much
 
o wait, maybe I can do it this way...
Take the set {w,x,y,z,1}. Then:
(w,1,(x,y,z))
RRR: =.1. RRL: =.1. RLR: ='1' RLL: ='1'
where ' is the preimage of .
and $.1.$ means for any $x,y\in M$ $.1. : xy \mapsto x1y$
 
Whenever we are selecting r objects out of n objects, we can do this n * (n-1) * ... * (n-r+1) ways if ordering matters.... I understand that each time our choice decrements by one hence we have one less choice for each item, my question is why does this go down to (n-r+1) ?
 
4:40 PM
Because:
1,2,3,4,5,...,r
n-0,n-1,n-2,n-3,...,n-(r-1)
 
restart, this is no different
 
Ah thanks.... Now I see 0 1 .... (r-1) is r items....
 
(1,x,y)
RRR: =id RRL: =id RLR: =1. RLL: =1.
(x,1,y)
RRR: =.1. RRL: =.1. RLR: ='1' RLL: ='1'
(x,y,1)
RRR: ='1 RRL: ='1 RLR: =id RLL: =id
(0,x,y)=id
(x,0,y)=x.
(x,y,0)='y'
 
5:02 PM
(0,q,x)
RXR: =0''q'1. RXL: =id
(q,0,x)
RXR: =q. RXL: = inconsistent
(0,x,q)=id
(q,x,0)='x'
(x,0,q)
RXR: ='0''q.1 RXL: x.
(x,q,0)
RXR: ='q' RXL: =inconsistent
In conclusion, the associators of any division by zero magmas are:
(a,b,c): (ab)c -> a(bc)
If 1 is right handed
(1,x,y)=id (x,1,y)=.1. (x,y,1)='1
If 1 is left handed
(1,x,y)=1. (x,1,y)='1' (x,y,1)=id
If 0 is right handed
(0,x,y)=id
(x,0,y)=x.
(x,y,0)='y'
(0,x,q)=id
(q,x,0)='x'
If 0,q are of the same sidedness
(0,q,x)=0''q'1. (q,x,0)=q.
(x,0,q)='q'
If 0,q are of the different sidedness
Only the trivial magma exists
 
By any chance, is there anyone speaks Turkish, here?
 
Now that the rules are established, it is time to check how bad is the nonassociativity of division by zero magmas:
First to recap the various types of nonassociativity, expressed with associators:
Associative: (x,y,z)=id
Jacobi: ((x,y,z),(y,z,x),(z,x,y))=id
Jordan: (x,y,xx)=id
Lebiniz: ?
Power associative: (x^n,x^m,x^p)=id for any n,m,p in integers
Alternative: (x,x,y)=id,(y,x,x)=id
Flexible: (x,y,x)=id
Elastic: (x,y,x)=id and (x,y,xx)=id and x(xx)y = (xx)(xy)
 
5:33 PM
Thus, division by zero magmas are:
Inflexible, non alternative, not jordan, not jacobi, may be power associative
and there you have it: Division by zero magma is the most f888ed up possible of a magma of which only power associativity holds
Therefore, one must abandon zero being an absorber otherwise you end up with magmas that are only power associative
Doing so and you have division by zero ringnoids, where zero is only an additive identity. As we shall see later, these guys have richer properties than their magma counterparts. More later
Theorem: Given any division by zero magma $M_D$ where $0^2\neq 0$. Then it is maximally nonassociative (i.e. All possible associators terms will not be the identity map)
Proof: Exercise
 
5:53 PM
Summary:
$M_D=(M,\cdot) = \langle M,0,1,q,\cdot,[,],(,,)\rangle$
 
chat has been taken over
 
escapes into Rambles to prevent being roasted
 
And this is why we don't delete our questions the second somebody answers them, folks... math.stackexchange.com/questions/2899809/…
The fact that the question got an immediate downvote for some reason probably didn't help, they must have felt stupid that the question had a "simple" answer and deleted the question
 
they aren't getting any backlash for it though
 
6:09 PM
if anybody wants to vote undelete on that question that would be cool, the question is actually kind of interesting
at least I think it is
 
the answer looks wrong to me though
$\tan 1$ is actually very close to $\pi/2$
 
it is yeah
that's what I'm ranting about, I think the asker saw the answer and thought "oops" and deleted the question before anyone could point out the mistake
 
maybe he ran away with the wrong answer and he will get a bad grade on his homework
aah
yeah that would be a bad move from the asker
I can't downvote a deleted answer :c
mfw the more time I spend on an answer the less people read it
@JackM he posted the question again
 
6:51 PM
Hello @MikeMiller, could you perhaps help me understand a comment you wrote on triangulating real projective space? (here)
 
I can try
 
Why do we need to antipodal map to take simplices to different simplices? I am struggling hard to get the idea of triangulating real projective space..
 
7:07 PM
Because you want to obtain a cell structure on $\Bbb P^n$ from the one you have on the sphere, so it needs to play well with the quotient
 
I thought it was Jack M = Jack M Lee = John M Lee in this chat, lol.
 
I'll try to ask differently. Suppose I want to specify the number of n-simplices and face maps for each n for such a triangulation. How do I approach?
 
7:41 PM
@LeakyNun you are a language rocket!
 
@Rudi_Birnbaum scheena dog is die unige Phrase ich kenn :P
 
@LeakyNun "Dees iis dees oanzige Gsàtzl wo-r-i woas"
 
wow
 
@LeakyNun Thats the original one ;-) my mother tongue
@LeakyNun you insert a consonant in between two vowels in word-border: "wo-r-i "
 
I see
 
7:45 PM
old "ei" gets "oa" in Bavarian "new ei" stays
like in swiss german new "ei" keeps "i" old ei stays
 
country roads
take me home
to the place
I belong
 
:-)
@LeakyNun Do you have also some specific "home dialect"?
 
Best mathematical equations you think are?
 
@Rudi_Birnbaum somebody else asked you this, I think, but I'm curious as well: what's your icon showing?
looks like some domain coloring in the complex plane, but it's not obvious what function it'd be
 
@Rudi_Birnbaum well I just speak standard Cantonese
 
7:48 PM
$\zeta$ function, but modified
 
okay...
 
@Rudi_Birnbaum i knew it
 
cut at y=0
and the halfs rotated by +- 45°
 
huh, neat
 
so that it gives something like an inverted zeta function, with the trivial zeros on y ...
 
7:50 PM
the things we see are the nontrivial zeros, right ?
 
hot jemand schwiizerdütsch gset?
 
@ÍgjøgnumMeg hoj, ja i
 
jo deeennnn!
Zeeeeas du alls paletti?
hahah na hey everyone
 
@ÍgjøgnumMeg Jo pascht schon!
 
7:54 PM
gad dusse am radla gsi
 
@ÍgjøgnumMeg am velo?
 
@ÍgjøgnumMeg hoe heb je bavarian geleerd?
 
Anyone a take on if there is a road from perfectoid spaces to RH?
 
@Leaky des isch nid boarisch!
lol
 
dutch i guess
 
7:58 PM
@Rudi absolutely no idea, hope this helps
;)
 
@Leaky und heißt es nicht "hoe heeft je" ?
 
nee, je hebt, hij heeft
 
@Leaky are you somewhere in DE?
 
@Leaky ah okey :)
 
8:00 PM
hoe gaat het ?
 
@Rudi_Birnbaum ik ben nog in Hong Kong... gewesen
 
I'm 2 hrs away from DE
 
@LeakyNun is dutch there common?
 
@LeakyNun Are you there?
 
@Rudi_Birnbaum not at all
 
8:01 PM
@geocalc33 So there are some possibilities ...
 
@Abcd yes
 
@LeakyNun :-)
 
@mercio ik heb probeerd met ieman in nederlands praten... nee ik begrapte niets
 
@Rudi_Birnbaum what do you mean?
 
So where are your Nethergerman abilities from, also varoious girl friends ...?
 
8:02 PM
@LeakyNun How to find the largest value of a 3rd order determinant whose elements are 0 or 1.
 
lol
 
@geocalc33 2h from Germany can be virtually the whole EU (incl. GB )
 
i said "goedemorgen" or something in a supermarket once and then she said how much I had to pay in dutch
 
that's awesome
 
I couldn't understand a thing
 
8:03 PM
@Abcd what is a 3rd order determinant?
@mercio probably not the best idea.. :P
also where is Ted
 
@mercio you know that Norwegian scetch about Danish?
 
I have heard that danish was a very peculiar language
 
@Rudi Kamelåså?
 
Jaaa!!!
@mercio youtube.com/watch?v=s-mOy8VUEBk enjoy all who dont know
 
@LeakyNun This^
 
8:04 PM
it's a finite problem :P
 
Sprekenzi deutsch?
 
@LeakyNun ?
 
@Rudi hob denkt i bin der oanzige wo des video kennt :D
haha
 
@ÍgjøgnumMeg :) I hob a boor freind z skandinavien ..
 
translation: I have a good friend in scandanavia
 
8:06 PM
@Abcd I don't know how to solve it apart from trying the 512 matrices one by one
which a compute can solve in seconds
 
@geocalc33 no : I have a few friends in S.
 
:) oh.
i tried
 
boor = "paar"
 
@Rudi i hob döt a freundin ket.. natürlich..
hahah
 
@ÍgjøgnumMeg :-))
 
8:08 PM
sorry
 
@ÍgjøgnumMeg sauguads Boarisch btw!
(evtl. substitute "denkt" by "gmoand")
 
hahaha in vlbg set ma "denkt" ;)
 
J'ai manque gfauxpas
 
alemannen hoid
 
@geocalc33 gfauxpas m'a manque
 
8:10 PM
hoi
 
@geocalc33 urban dictionary ..
 
@LeakyNun always criticizing me
go do math for 10 hrs
Sorry!!!
 
i have lots of respect for him he seems to be excellent in maths (and languages)
 
and a jolly good fellow!
for hes a ...
There is still no news from Mochizuki/Scholze-Stix. Wonder whats going on there ...
Summer is almost over. They promised that it will come up in the summer ...
 
8:17 PM
@LeakyNun Why do we get same results by expanding along any row or column of determinants?
 
@Abcd it is 2
and the matrix is $\begin{pmatrix}1&1&0\\0&1&1\\1&0&1\end{pmatrix}$
 
@LeakyNun I wont get computer in my exam.
 
@Abcd I don't know of a simple explanation
 
1 min ago, by Abcd
@LeakyNun Why do we get same results by expanding along any row or column of determinants?
Does anyone else know the answer to this^^^?
@LeakyNun While learning determinants are we just supposed to "accept" many of their properties and stuff?
 
yes
because the proofs are harder than the computations
 
8:19 PM
Oh, thats so "un-mathy" of determinants.
 
proving det(AB)=det(A)det(B) requires group theory or linear algebra
indeed
 
Okay, thanks for telling me that otherwise I would have been worried about proofs all the time!
 
@Abcd The determinant is an anti-symmetrized product
 
(Dont know what that means as of now)
 
@Rudi_Birnbaum that's the linear algebra path :P
@Abcd I mean, determinant is kinda a special case
 
8:22 PM
@LeakyNun yeah but simple ...
 
@LeakyNun Special case of?
 
@Abcd of proofs being important in maths
even first year university courses (like the one in my university) that prove everything don't prove that det(AB) = det(A) det(B)
 
Okay.
@LeakyNun Isn't calculus much better than Algebra??
 
depends on what you mean by better
 
better = interesting
 
8:25 PM
then that is quite subjective
 
@Abcd calculus is the Walt Disney version of Analysis which is a branch of maths.
 
I find it much easier than Algebra (high school)
like 10 times easier!
 
@Abcd What again is high school algebra?
 
@Rudi_Birnbaum Complex Numbers, THeory of Equations, Progressions and Series, Permutations and Combinatins, Binomial theorem, Determinants, Matruces, Probability , Inequalities involving Means
 
@Abcd Thats a lot, but you'll find most of it in Analysis except matrices and probability.
 
8:29 PM
Oh
 
probability woule anyway be part of "Stochastics" and matrices of "Linear Algebra"
 
@Abcd what about the hard integration questions?
 
@LeakyNun They are fun at least, you can keep trying them as long as you want. Hard algebra questions suck blood! You dont even know what to try.
 
Well a good command of double summation might do was well.
 
8:51 PM
definition of smooth surface
 
9:13 PM
@Abcd Of course not
The expand-by-row-or-column definition of the determinant is good for computation but horrible for understanding
or for theoretical proofs
The best way to show it is to find a different definition of the determinant, and show that that definition equals what you get when you expand by any row
 
@LeakyNun sorry I mistranslated your french. I thought you said "Gfaux pas doesn't miss you." Anyway I'm sorry and you are a great mathematician. My mistake.
 
9:30 PM
The construction of the sentences that involve "missing" is really strange in French.
 
0
Q: Dummit and Foote Universal Property of Tensor Products

user193319Here is the theorem giving me trouble: Here is theorem 6, which is invoked in the proof of theorem 6: Here is the proof of theorem 8: Here is the sentence giving me trouble so far: "Since $\varphi$ is an $R$-module homomorphism, the generators of the subgroup $H$ in equation (3) all ...

 
definition of smooth surface?
 
10:06 PM
@LeakyNun Odd. I proved that in every linear algebra course I've ever taught. It's very straightforward using elementary matrices (and doing $A$ singular as a separate case).
 
Hi @TedShifrin, can I ask you what time is it there?
 
@Ted Extending that rank matrices exercise to the case of symmetric matrices is also nice.
 
 
1 hour later…
11:21 PM
prove tha tthe $x^2+y^2=1$ is a smooth surface globally parametrized by the $φ(r,θ)=(cosθ,sinθ,logr)$
i dont have a definition of a smooth surface...
do i just say that $φ$ is smooth hence the surface
and how do i prove that indeed this parametrization gives me a cylinder
 
@ManolisLyviakis I believe--and correct me if I'm wrong, anyone--that a surface is smooth if it is the image of a smooth function, so yes, $\varphi$ being smooth works. As for showing that it gives a cylinder, try showing that every point $(\cos \theta, \sin \theta, \textrm{log }r)$ satisfies the equation, and conversely, that for every point (x,y,z) that satisfies the equation, you can find $r$ and $\theta$ such that $(x,y,z) = (\cos \theta, \sin \theta, \textrm{log }r)$.
 
11:38 PM
yes only think i can think of too
thanks
 
No problem. :)
 
problem is
suppose a point(x,y,z) of the set $C:x^2+y^2=1$
i need to prove that it belongs to the image of $φ$
 
Yes, that is the real hard part. Particularly, showing that x and y are indeed the cosine and sine of some angle
 
ye and i dont know what the role of logx is
 
I'll have to think on that for a bit
log r is there because r is always nonnegative, but the cylinder goes to both positive and negative infinity, so you need a function that goes from nonnegative numbers to all real numbers--which log does
 
11:43 PM
i think i found it
if point is in the cylinder
 
Do tell!
 
on*\
then its projection to x and y axis
will do ?
 
I was thinking, if a point (x,y,z) is on the cylinder, then x and y are the legs of a right triangle with 1 as the hypotenuse.
 
From that you can recover the angle.
I guess that's similar to how you're going about it, so that should work I guess
A more algebraic way to see it is just to let $\theta = \cos^{-1} x$ (with possible adjustment based on the signs of x and y), and then because $x = \cos \theta$, from $x^2 + y^2 = 1$ you immediately have that $y = \sin \theta$.
 
11:50 PM
yeah
i think i figured it out
 
Awesome!
 
a point in cylinder needs t2 angles
to be defined
 
Indeed. Or an angle and a height.
 
the angle on how high it is for x axis and the angle that makes with the y axis
 
I agree
 
11:52 PM
then i just write down the x,y in terms of those 2 angles
 

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