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00:00
Over my head
And as W|A shows , this can be expressed the sum of these 2 integrals is actually $\pi\ln\frac34-\Im\operatorname{Li}_2\frac{3i}4$ as Cleo showed.
(or using the inverse tangent integral as sos440 showed)
That's all.
I kill the first integral from one single shot if I introduce the variable $a$, as $\log(1+a x)$, and then differentiate with respect to $a$.
Okay, my POTD tomorrow will be the original question from which these 2 integrals come from.
I need some sleep now.
Ok
Good night @Chris'ssis
 
1 hour later…
Ram
Ram
01:16
Hi, any one in here?
I am @Ram
Ram
Ram
Hi, do you know any thing about Intersection pairing?
@Ram No, I don't know much math
Ram
Ram
hmmm
02:19
@FernandoMartin Jacobson is sneaky.
How do you find the area of a general quadrilateral, given only the side lengths of the quadrilaterals?
I would prefer if you used an example as well.
@TechMaster100 You don't.
Ram
Ram
@Mike, can you help in understanding Intersection Pairing?
I am trying to construct intersection pairing matrix (simple case S1 x S1).
at H1 x H1 to Z
@TechMaster100 It's a good question, but a quadrilateral is not determined by the length of its sides. Related.
02:35
@Ram I wish I could help! I don't know intersection pairings.
Ram
Ram
@Mike :-(
Can i ask for recommendation of books in math.stack exchange
or do i need to ask for it in wiki community
or something
Ram
Ram
02:51
@nerdy, you can ask under soft questions tag
at math.stackexchange
thanks!
@Ram, usually that's done on $4n$-dimensional manifolds so that the matrix will be symmetric. Do you know Poincaré duality so that you can understand it geometrically?
Hi @Mike
Hi @Ted
Ram
Ram
@TedShifrin, thanks for reply. I am trying to construct an example. I did it on S1 x S1.
But ok, lets take S1x S1 x S1 xS1 and H2 x H2.
Better, do $S^2\times S^2$ or $\Bbb CP^2$. So you know cup product?
Ram
Ram
02:57
So, this is exterior algebra generated by 4 elements, say p,q,r,s. So H2 will be generated by wedge sum of two elements (so 6). Now I am getting 6 x 6 matrix
No exterior algebra !
Hi @user127001
Ram
Ram
Yes, I know cup product.
Why are you doing exterior alg? You want the cohomology ring.
Ram
Ram
Yes, but for n torus, the cohomology ring is exterior algebra generated by n elements right?
You can represent cohomology by diff forms, which I adore, but no exterior algebra of vector spaces here.
Ram
Ram
03:00
I don't know diff forms :-(
Ah ... Do my two examples before tori.
@Ted I think we are completely skipping rings in our algebra class. Last class we spent it on interesting symmetries (kaleidoscopes, gyrations, etc.) and the class before that, game theory
Ram
Ram
I got [1, -1, 1, 1, -1, 1 ] in the reverse diagonal positions and wedge of p,q,r,s.
This sounds just as crazy as Conway, @user127001.
Ram
Ram
@TedShifrin, I am having difficult time with exterior algebra. So, trying to learn it :-) with hatcher...
03:02
@Ted during the game theory class, he bet a student $20 in a game of dots and boxes and he lost lol
Ram
Ram
But, I dont know what I have to do with p \wedge q \wedge r \wedge s in the matrix.
You should learn differential forms on manifolds , @Ram :) forget torus and do my examples, please.
Ram
Ram
Sure, let me start
@Ram: That's the generator of $H^4$.
Ram
Ram
yes, but H2 x H2 should be mapped into Z right?
03:05
In some ways, @user127001, rings are more fundamental than groups.
Yes.
Ram
Ram
but why I got H4 generator? Where I did the mistake?
That is the generator of the $\Bbb Z$.
Ram
Ram
So, it seems my calculation is alright?
Ah, lhfs.
Ha! I just noticed that I have a MetaStackExchange account and that one of my MSO answers was migrated there. I love the comments to the answer.
03:08
You need a 6x6 matrix for that torus. Hence the reason I told you to do the other ones.
Real on-topic comments.
@robjohn you have not changed your profile picture for how many years?
Hi @Pedro
@Pedro: The friend I had dinner with in ATL was suggesting we visit BA:)
@robjohn doesn't age ...
03:11
Wow
How did you decide on the color @robjohn
@tedshifrin well ill be waiting at Ezeiza =]
@user127001 it seemed a mean color.
I think red might look pretty mean
@user127001 but I don't think it is as nice for an avatar.
But I thought you wanted it to be mean for an avatar
Ram
Ram
03:15
@TedShifrin, okay I calculated Ring of CP2that is $mathbb Z[x]/x^3$. So, I have to start with H2 x H2 -> Z right
But your $x$ is in degree 2, @Ram, right?
Ram
Ram
yes. x is in degree 2
Do you understand what's going on geometrically?
Ram
Ram
Nope.
I couldnt find material to read more about it..
sigh. Too much fancy stuff and not enough understanding. The generator corresponds to a projective line in the projective plane. And a line intersects another line in ....
03:19
wow... I just got an upvote on an answer from 2011.
talk about digging up old questions
What are you waiting for, @Pedro? :D
Ram
Ram
@TedShifrin, Hatcher din't gave any geometric interpretation :-(. I dont know any better book to Hatcher. Can you suggest some thing for this?
Surely he does when he discusses Poincaré duality?
Ram
Ram
yes
Hi @Ted
Ram
Ram
03:29
he gives this as connection between cup and cap products
Griffiths and Harris discuss all this in chapter 0 of their algebraic geometry book.
Sadly, alg top books don't do a good job of providing insight. One needs professors for that :(
Really
Some of us do, you know, @user127001 :D
lol
Wow this Griffiths & Harris book costs $116.39
Anyone have much experience with Mathematica?
03:31
Yes, @Mike
Ram
Ram
OK, great I will find that. And I have another question,
Griffiths and Harris, despite dozens of errors, is superb.
Is it better than Hartshorne
Ram
Ram
f: P2#...#P2 (2n sums) to T2#......#T2(n sums). If I look at f_*(H^1) how does it look like? I mean can we say some thing about this with out any information on f?Lets take coefficients in Z2.
@Ted Does that mean you do or people do?
03:33
Far better. It's not slavishly algebraic. It is based on analysis, geometry, topology. It's a very different style/approach to the subject.
Ram
Ram
by looking at cup products this looks like trivial in this case.
Not trivial, @Ram, but easy, yes.
Yes @Mike :)
Ram
Ram
Me and Mike thought its trivial on H^1 isn't it?
Since in Orientable case we have, a_i cup a_i = 0, but in non orientable surface f_*(ai)^2 is zero iff ai is zero.
Huh, what are you doing now, @Ram?
Ram
Ram
I mean, I am talking about generators of both cases
at H^1
03:36
@Ted Dles it play nice with complex functions? I want to simplify a function I have involving the principle branch of sqrt.
It is not good about branches ... I've not tried that sort of thing.
Ram
Ram
and looking at cup product in H^2 (Sorry page expired)
Darn. I don't want to be too careful about this. But I need something to be.
Ok, bedtime for me. Tennis early am
Night, all.
Ram
Ram
Ok, good night.
03:41
Night
 
1 hour later…
04:49
what's an example of a distribution that is not a sum of dirac deltas weighted by normal functions?
05:25
@seaturtles what's a normal function
everyday, usual, familiar
and can you explain what you mean by weighting a dirac delta with a function? i don't know that notation/terminology.
$\sum_i f_i(x)\delta(x-a_i)$
right, but that reduces to a sum of dirac deltas weighted by complex numbers.
seems silly.
so $x\delta(x)=\sum c_i \delta(x-a_i)$ for complex numbers $c_i,a_i$?
erm
yes I suppose $f(x)\delta(x-a_i)=f(a_i)\delta(x-a_i)$
05:28
yop
so $f(x)+\sum c_i\delta(x-a_i)$ in that case
yeah that's the right question i think
that gives a "continuous part" and "discrete part" and this suggests the question if there's anything in between
the answer should be "yes", a couple months ago i'd be able to give an example on the spot
gimme a sec
@seaturtles the answer's definitely yes, but i can't find an example in my notes. (we should say $f$ is locally integrable to make the 'obvious' class of things work, but still be able to find stuff that's more general.)
@seaturtles oh, right. every measure gives you a distribution. convince yourself that there are more measures than $df + \sum c_i \delta(x-a_i)$
05:41
i don't have an example for that, either, but it's more "obviously true" to me
@seaturtles i just thought of an example, but it's gross
haha
my friend is such a heavy sleeper I just unlocked his cell phone with his finger
wish I knew how smartphones worked
06:34
wat
07:05
fingerprint authentication
ook
@Sawarnik
 
1 hour later…
08:32
@freeze Hi.
08:47
hi hi
almost 700 reputation ^^
and I just made 700 ^^
congrats :-)
over 9,000 hours later...
09:00
@skullpatrol ?
09:11
need feedback
http://math.stackexchange.com/questions/771119/prove-that-if-t-in-t-and-q-in-q-but-q-neq-0-then-qt-in-t
09:29
Should the question In a group of 26 people, is it possible for each person to shake hands with exactly 3 other people? be closed as a duplicate of Constructing Cubic Graphs of Even Order? The later is clearly more general. However, it uses somewhat different terminology.
you! -___- ^
@usukidoll All that I am saying is that when I see this: Prove that if $t \in T$ and $q \in Q$, but $q \neq 0$ then $qt \in T$ I have no idea what the question is about.
oh o_o
When I see: Is product of a transcendental number and a non-zero rational number again transcendental? I immediately know what the question is about.
strange.. I've written my questions like that for a while now... is it part of the reason why it's taking long for me to even get an answer sometimes?
09:33
Informative titles are recommended, see How can I ask a good question?. (I left you this link in a comment.)
yeah -- I'm reading it now *scrolls through****** -______-*
But as far as your question is correct I do not see based on what you claim this: As a result, $t \in T$, but $q \notin T$, so $qt \notin T$.
sorry.. I'm new to proof writing
practice makes perfect right ?
at least I"m not chucking the book out the window ... since the course was a roller coaster for me
What I'm trying to say is that although t is transcendental, q is a rational and by that prop... all rational numbers are algebraic which clearly breaks the definition of transcendental (numbers aren't algebraic period)
This claim, if I understand you correctly, says that: Product of a transcendental number $t$ and an algebraic number $q$ is an algebraic number $qt$.
yeah, but clearly we can't have that for t if it's transcedental
09:38
From the title of your question it seems that you are trying to prove that $qt$ is transcendental. But you end your proof claiming that $qt\notin t$.
blah ... q is rational... by the prop... it's algebraic... t is transcedental which means that it's not algebraic so we can't have $qt \in T$ because q isn't transcedental oh boy I should've put that instead of the massive symbol line
Try $q=2$, $t=\pi$.
I'm disproving that statement.. because if q is rational... and by that prop all rational numbers are algebraic, then clearly it doesn't belong in transcendual
The number $2\pi$ is not algebraic.
Which statement exactly do you want to disprove?
Or are you trying to prove it by contrapositive?
The main thing that bother me: You seem to be claiming that $t\in T$ $\land$ $q\in A$ $\implies$ $qt\in A$. This is not true.
Moreover I do not see at which place of your proof you are using $q\ne0$.
what the ! -_- $ t \in T$ that's transcendental It's NOT ALGEBRAIC! so that t shouldn't be in that A at all!
q is rational... by that prop all rational numbers are algebraic.. okkkkkk....... but is it going to be in T... no because anything in T is not algebraic.
09:47
That's true. We have $q\notin T$, which is the same as saying $q\in A$.
I agree with this.
I haven't switched anything..I'm not doing converse... contrapositive...or negation .. just straight out disproving the statement... I saw right through
but for other proofs like oh relations...functions...cardinality... I'm screwed like crazy
@MartinSleziak I found your name on Wikipedia :D
OO link!
Just the name, not an article :D Here, en.wikipedia.org/wiki/Tibor_%C5%A0al%C3%A1t
But if you are doing just direct proof, how come you end up with $qt\notin T$, when you are trying to show $qt\in T$?
09:49
I wanna disprove ^
So you want to disprove the statement in the title of your question?
yesssssssssssss
how the heck can we have q in T if the def of T says that the number isn't algebraic
q is rational.. and by that prop... all rational numbers are algebraic
Oh, I should have noticed this in your post: We are going to disprove this statement.
which is clearly a red flag
yeahhhhhhhhhhhhhh
But I do think that the statement is true.
09:50
no......
I'm trying to disprove this part $qt \in T$
because how the heck can q be in T when it's rational and by prop... it's algebraic.. T doesn't have algebraic numbers...period.
$ t \in T@$ I understand that clearly
But the claim does not say that q is in T.
$q \in Q$ which is rational
$t \in T$ transcendual
$ qt \in T $ so my q and t is supposed to be Transcendual
works for T, not for Q
Why do you claim that $qt\in T$ implies that both q and t are transcendental?
What about $1\cdot\pi \in T$?
that's just a pi
if I multiply right through
The product $1\cdot \pi$ is transcendental. But clearly, it is not true that both $1$ and $\pi$ are transcendental.
09:54
try q = 10 and t = $e$ >:)
That's the same thing. Both $e$ and $10e$ are transcendental.
o_____O! oh f....... wait if I take the product of q and t then the result will be transcendental.... and it would belong in T
so I was just doing this proof with letters and not coming up with let q = 3 and t = $e$
sigh this is what happens when self studying fails and the prof fails to teach clearly
S_S
what if I'm not allowed to take the product of q and t... what happens then?
I am not sure whether I was able to show you that you did not disprove the claim. But if you want to try to prove the claim, you could try proof by contradiction.
You could say: Let us assume that $q\in\mathbb Q$ and $qt\notin T$. What can we say about $t$ then?
09:58
I would still disprove it like the wind >:D because assuming that I can't take the product or assign values to q and t . wham
t is not transcendual
which means t is algebraic like that q being a rational number and being algebraic by that prop
If you manage to show that $q\in\mathbb Q$ and $qt\notin T$ implies that $t$ is algebraic, you get a contraction. And thus you get proof of the claim in the title of your question.
@user3123545 hi.
but what if I still want to straight up disprove the statement... unless I was thinking about it wrong slightly for $qt \in T$
But why do you want disprove a statement which is true?
because I have no solid guideline that's what.. I'm lost in proof writing land really along with the rest of the class, so I've been trying to reread again
10:01
I had a question today, showing a diagram sort of, showing something like this: http://www.regentsprep.org/Regents/math/algtrig/ATS2/normal67.gif

now there were 2 hints, 16% on left showed 185 and 16% on end showed 215 (assume the 16% on left is 84 cause 100-16. Now they wanted me to find the avg in this all, i only know that 68% is 30 (215 - 185). How can I know the avg?
wow guess I need more time to master this cheese whiz
It seems that we keep misunderstanding each other, so it is probably the best if I leave this for someone else.
damn I see the point now qt the product of q and t.. let q = 5 and t = $e$... so $5e \in t$ which means it does belong... I had no idea you can assign numerical values to these problems
sighhhhhhhhhhhh
Anyway, I have edited your title, at least to include the information what $T$ means. (I think it is cleare that way.)
skull I'm sad now :(
damn it's like there are so many ways to look at the claims and there is the thought of what if this and what if that this that this this that
10:05
Write down as much as you can...
ha ha very funny
I had no idea that I would be able to assign a number to q and t
In fact, after some practice the proofs from introductory courses should not be that difficult. You basically have to write down the definitions and things that you know. If the proof is not working, that you try contradiction or contrapositive. If it is claim about integers, you can try induction.
I just looked at it with just the letters played
it's only my first one :/
So it's basically mastering a few basic techniques. But you can achieve that only if you try enough exercises.
but at least I'm reading and trying :/
10:08
What textbook are you using?
Passage to Abstract Mathematics
it's really a meh book
I learn better with ROsens DIscrete Math book thing and other materials
@usukidoll So you have learned something new. In general it is useful to look for specific examples. For example, if I was trying to do some proof and if I had an idea: Now if I show that the product of two irrational numbers is again irrational, then I will be able to finish this proof. Maybe after few unsuccessful attempts I would notice that $\sqrt 2\cdot\sqrt 2=2$ is a counterexample to what I was trying to show. And I would realize that I have to try something else.
ok... so what about
prove that if $ t \in T $, then $ \frac{1}{t} \in T$. That should be easy.. since we have transcendental numbers that aren't algebraic... so if I let $t = e$, then $\frac{1}{e}$ and that would be in T?
Have you gone to a university library and looked at what is available @usukidoll?
It is good to look at specific example. But noticing that some claim is valid for one particular example is not the same as a proof of that claim.
To prove it, you should show that it is true for any $t\in T$, not only for $t=e$.
Maybe this would help: Can you show that $t\in A$ $\implies$ $\frac1t\in A$?
(Or maybe you have even learned theorem saying this.)
Of course, we assume $t\ne0$.
10:14
T being algebraic implies that $\frac{1}{t}$ is algebraic
Well.
Now if you want to show for $t\ne 0$, $t\in T$ that the inverse $\frac1t$ is transcendental.
You could say: If $\frac1t$ were not transcendental, then it would be algebraic.
ooooh by definition 2.7.8 A number s is an algebraic number when there exists some $p \in Z[x]$ such that $p(s) =0$. Let us denote the set $A = [x \in C $: x is algebraic]$
But if $s=\frac1t$ is algebraic, then $1/s=1/(1/t)=t$ is .... ?
Off topic: You are doing Exercise 2.7.13 from that book, right?
HOW DID YOU KNOW THAT D: PSYCHIC POWERS? ^
if we have $ t \in A$ then there exists a polynomial $p \in Z[x]$ of the form that long string of polynomial stuff
10:18
@usukidoll He must be having that book, or some pdf.
lol he must own the book...I can't find the pdf XD
No, I do not have any psychic powers. If you do not mind, I will add the information to you post. (In general it is a good practice, that a question should contain the source. In particular, if you keep referring in your post to things like Proposition 2.7.9.
and this is why I prefer differential equations over this ROFL
uh huh
damn this sucks with a show off professor. no one is passing really everyone failed the 2 midterms
lol everyone will fail the final
and just give mercy grades of C to make us feel better.. . -__--
I don't wanna learn like this! I swear my uni has less quality control than my community college
my entire calc iv was like that. everyone failing the homework, midterms, and final, yet everyone got C's. So yeah you can do whatever like not show up for class and you can pass.. super sarcasm
I prefer to post links in chat like this: Have you solved problems in your sleep? at MathOverflow.
10:22
@MartinSleziak How do you do it?
@Sawarnik Have a look here to see the source.
@MartinSleziak Oh! Nice.
For each chat message you have arrow icon on the left, where you can click on reply to this message, or permalink or on history.
If you choose history, you will see the source code of the message. (And of all revisions, if it was edited.)
Yes, I see.
You can find much more about various ways how to format links in markdown help. But most of that is about post - AFAIK only this version works in comments and in chat.
10:39
:( I wish I had a better professor who taught the most important course in the universe
 
2 hours later…
12:15
What course again
0
Q: Does a dot or period (.) get italicized or capitalized?

Awal GargWhen we italicize text with the dot (.) or period symbol, does it actually change the (.). So, is . different from . Can anyone tell which of them is italicized? And same way for capitalization. . different from . Does it matters? P.S. I am not sure if I should ask this here, ...

2 hours later...
this is important for math people
says who
12:17
, ,
12:31
@AwalGarg I think no.
. normal . italicized
@AwalGarg serious business
@robjohn are you here? I need your help...
@skullpatrol Indeed, in font families with square dots, the italic font has a slanted square dot
@ccorn I am of the opinion that a point has no size.
12:38
@skullpatrol What's your opinion about periods?
same, they are full stops
did someone ping me?
5 mins ago, by Karl Kronenfeld
@AwalGarg serious business
@Sawarnik what do you think is no?
@skullpatrol yeah, i see that now.
@skullpatrol I'd rather go with Einstein. If a dot can stop something, it must have size, otherwise it would be a singularity.
2
12:40
@AwalGarg That . gets italicized and ...
@Sawarnik oh.
@Hawk HELLO!
@Sawarnik helo helo!
@Sawarnik actually, it gets. zoom in like 200% and you will see
@AwalGarg orly. let me check.
12:42
@ccorn I only like a few of his quotes and that is not one of them.
@skullpatrol If I was wrong, one was enough?
@skullpatrol Agreed, but still suited for application to italicised dots :-)
oh yes, a colon also applies to that question, isn't it?
yes, and a semicolon
12:45
@skullpatrol no, i think.
Certainly a colon gets italicized.
@Sawarnik did u see the difference?
@KarlKronenfeld but its made of two periods
@AwalGarg wait, i m bit overloaded now, so sometime later..
@AwalGarg yes, I really like your idea
but they are aligned
:
:
12:47
@KarlKronenfeld i think, it would be easier to see the effect in a colon because the hinge point of slanting the character is farther away from one of the dots
@skullpatrol yeah, thats what I mean
@AwalGarg yep
But, I wonder, do the individual dots also tilt...
@AwalGarg: While we are at it: Does a space character get italicised? IMHO spaces are not rendered as glyphs...
@ccorn It specifically does not matter...
ok wait, it does...
@skullpatrol two dots are always aligned, aren't they?
12:50
@Hawk vertically
@AwalGarg If nothing else, it gives us the measure of the angle at which the dot would tilt.
if the character after the space is not italicized, then it would matter
@skullpatrol does the direction actually matter?
@KarlKronenfeld i knew it would be mathematical.
@AwalGarg You are thinking of the space character as a white box I suppose?
12:51
@ccorn yeah... umm, you make a point
it might be a horizontal line
@Hawk on a page, yes
ok, underscore _ applies to the question as well
@skullpatrol how? they are afterall two dots, you can always join 2 dots with a straight line...
that as well is a horizontal line
12:52
Next detail: In serifed italic fonts, are the serifs slanted?
_ ___
i_i (i am trying to italicize _)
3 mins ago, by Karl Kronenfeld
@AwalGarg If nothing else, it gives us the measure of the angle at which the dot would tilt.
actually, a dot should be an ideal circle...
but, we don't come across ideal things
@AwalGarg Actually, a dot should ideally blend in with the surrounding text...
12:54
@ccorn why?
17 mins ago, by skullpatrol
@ccorn I am of the opinion that a point has no size.
s/blend/fit/
@skullpatrol everything is made of points, so, everything is of no size?
@skullpatrol you are contradicting your own point now
btw, anyone here knowing PHP?
12:57
no
@AwalGarg no
@skullpatrol explain
@AwalGarg Fortunately not. I am versed in Perl however.
@AwalGarg we can pretend, as long as you don't post a wall of code
I also know some perl
@KarlKronenfeld @ccorn do you happen to know about - Object of class mysqli_result could not be converted to string
12:59
@AwalGarg dunno, but SQL results should probably be arrays

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