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02:00
@AlexanderGruber yes classic
@user her vocal range is better than I expected
user143442
i'm in the second song now
user143442
I like it
user143442
of course, she's a very good singer
user143442
she can sing live
i'm definitely liking the other tracks better than break free, which is the song i'd heard by her most often
@anon: you might appreciate this. i'm finding it pretty readable. maybe it's all stuff you know though
@AlexanderGruber: how do you like the coup
user143442
I'm also liking Zero 7, their sounds remind me of D.A.N.C.E. by Justice
user143442
I'm listening to a song with no singing
user143442
Seeing Things
02:11
@MikeMiller DONT TRUST THE POLICE NO JUSTICE NO PEACE
reasonable answer
they're great
insanely clever
@user the girl singing with them is Sia btw
when I was in college I had to institute a strict ban on the pageant of the bizarre during parties because it makes me cry when i'm drinking
user143442
in which song
02:19
@MikeMiller I asked a question on MO. I have no idea how hard it is, though I'd honestly be surprised if its tractable. mathoverflow.net/questions/222903/…
the pageant of the bizarre @user
user143442
oh that's the one i'm listening to right now
and You're My Flame and probably a couple others
user143442
what a coincidence
user143442
i love sia
02:20
@PVAL: Are there no homology S3s where it's known that there's only a couple tight contact structures?
@MikeMiller I don't know. There's ones with finite amounts, but these are often computed in a way where I don't know how to get the Legendrian surgery diagrams for them.
I can ask Ko about this next week if you want.
@MikeMiller I've tried understanding the things people have said about ones that are SFS's , but maybe there is more known if I allow people to do whatever they want to with the boundary.
That would be nice.
If anyone would know..
I don't think Bob knows of an example, though I don't think I've asked this directly to him.
I don't know if he thinks about Stein fillings but good odds he can produce homology spheres with a small number of say symplectically fillable contact structures.
02:26
Are there ways of computing the classical invariants of knots in these structures?
I wouldn't know.
@PVAL: Something I was thinking vaguely about yesterday. Gromov has a theorem that every almost symplectic structure (nondegenerate 2-form) on an open manifold is homotopic to a symplectic one. Are there any good ways of telling if something has an almost symplectic structure?
user174558
Hi @mike I hope you got my email about my new email.
I did.
user143442
@AlexanderGruber I already finished the tracklist, thank you, it's very good music, I'll add it to my favorites list
user143442
@Jasper I didn't get your email
user174558
02:33
Hi @Mahnax I hope you got my email about my new email.
@Jasper Hi Jasper! Yes, I received it.
user143442
I feel excluded :(
@MikeMiller Not that I know of. Immersions into codim-0 manifolds which are symplectic, J-holomorphically embedded submanifolds for tame ACS, and Stein manifolds are really the only ways of constructing symplectic structures I know about.
Figures.
(In particular it would be nice to know which punctured compact 4-folds admit a symplectic structure.)
eg I wonder if $\#^3 \Bbb{CP}^2 \setminus \{pt\}$ does.
What is the genus of the sum of the generators for $H_2$?
02:41
No idea. Is there an obstruction there even for noncompact mfds?
Well probably if it were convex at infinity at least
@user great, glad to hear it
Oh I'm not expecting it to be good near infty.
theres probably things you can do if you assume something like "weakly convex at infinity".
good god
how much algebraic topology do i have to take before i have any idea what the words that you are saying even are
02:43
Well it isn't algebraic topology.
...so, not very much then
OK good I'm on track
One other Q: are there known examples of M and exotic M (compact) that both support symplectic structures?
closed?
02:43
yah
I know plenty of compact not closed examples
Yeah but those are pretty much just noncompact, so that's cheating.
Have a pretty simple linear algebra question if anyone is willing.
Not sure where to begin.
Not really... they are Stein fillings of their boundary.
@Mahnax ok so
02:45
Any way theres examples here arxiv.org/pdf/1402.0801v3.pdf
I'm sure there's older examples.
can you simplify (AB^{-1})^{-1}
Here's one on $\Bbb{CP}^2 \# 5\overline{\Bbb{CP}^2}$.
@AlexanderGruber $(BA^{-1})$
ok so what's $(BA^{-1})(AB^2)$
I have a mild hope that one can tame smooth manifolds in 4-dim by thinking about symplectic structures, like maybe that there's only fin. many symplectizable ones.
02:47
?
@AlexanderGruber No idea. I've never encountered that sort of operation with matrices before.
well blow-up the plane n times
theres infinitely many of them
I mean on a given topological manifold.
@Mahnax Multiplication?
Forget that these are matrices. That isn't important.
I don't suppose you can just say that $(BA^{-1})(AB^{2})=I_{n}B^{3}$?
02:49
You sure can
Well, that's nifty.
so what's X then?
@MikeMiller Symplectic structures help distinguish smooth structures though.
@AlexanderGruber $B^{-3}A^{-1}$?
02:52
@PVAL: But infinitely many of them? The standard constructions I know of infly many exotic structures are like Fintushel-Stern knot surgery which doesn't involve the symplectic structure.
Other way around?
$A^{-1}B^{-3}$?
$\begin{eqnarray*}X^{-1}A&=&B^3\\X^{-1}&=&B^{3}A^{-1}\\X&=&(B^{3}A^{-1})^{-1}\\X&=&‌​\cdots ? \end{eqnarray*}$
@PVAL: I'm being silly. Dolgachev surfaces are all homeomorphic Kahler manifolds, none of which are diffeo.
Sigh.
$X=AB^{-3}$
@MikeMiller Most invariants for smooth structures are based around Kahler/symplectic/Stein geometry.
02:56
got em
Thanks very much for your help!
No problem
user174558
No problem, LOL.
I don't know ways to tell apart smooth structures that don't ultimately come down to instantons or monopoles.
@MikeMiller Dolgachev gave a series of talks here. They were unintelligible.
02:57
But this is probably just a corollary of my training.
lol
I felt the same when Okounkov came here.
user174558
When is Miller coming to my town?
i thank you guys for that matrix discussion, as it motivated me to work out how to make mathjax work in this chat
@MikeMiller Someone named Yasha gave a talk here about a week ago that I enjoyed, though I'm unsure if many other people did
test: $\int (\liminf f_n) \leq \liminf \int f_n$
oh sweetness
Emmy talked here a while back and was a good speaker. I didn't get much out of it, though, because I didn't know much contact geometry then.
What did he talk about?
03:03
Everything.
Flexibility
Rigidity.
You name it
Classic Yasha
It was like he'd describe a problem that was very interesting that I could understand. Then he'd describe how to do it in some " easy" case (which I wouldn't understand). Then he'd describe how one should try to solve the open case.
He did that about 8 times
I guess he probably just listed a bunch of things he'd like to know.
basically
@MikeMiller For instance he talked about what conditions on $r_i$ and $s_i$ you need for a symplectic embedding $D^2_{r_1}\times \dots \times D^2_{r_n} \to D^2_{s_1} \times \dots \times D^2_{s_n}$. The total volume is one obvious condition, Gromov famously gave another, but given those two what else can you do?
(r_i,s_i denote radii of the disks)
Did he give any other exs?
03:13
I think he said that "stably" these are the only ones.
I.e. if you product on both sides by a bunch of big enough disks with the same volume it eventually always embeds
Interesting
He stated that a Legendrian knot on S^3 which bounds a Legendrian disk on the complement of the 4-ball always has tb 1. Therefore adjunction shows you can never have such a Legendrian disk on the outside of the 4-ball.
That was probably what I got out of the talk.
He mumbled about h-cobordism and the hairy ball theorem as well.
Big fan of those.
His example of a flexible result was h-cobordism and a rigidity result was the hairy ball theorem. I think the audience probably thought those results differed a lot more in difficulty then he did.
my words became jumbled
They are pretty good examples though.
03:24
I'm sure he said something about the nearby Lagrangian conjecture, though I don't remember what.
user174558
I finally got the Teacher Badge on this site.
user143442
@Jasper congrats
user174558
But most of my answers have 0 votes.
user143442
I'm gonna vote for all your answers
user174558
@user How are you feeling these days?
user143442
03:31
Good, why?
user174558
You seem very troubled.
user143442
why do you say so?
user174558
From the way you behaved.
user174558
If you have a problem, you can talk to me about it.
user143442
I don't have any problem
user174558
03:38
Then good. My job is done.
user174558
Yes, indeed.
user147690
05:41
@Ashwin How you doing buddy?
06:36
0
Q: Am I not ready for a math textbook if I have to resort to solutions early in problem solving?

crocketI started studying "Introduction to Mathematical Logic, Sixth Edition" by Elliot Mendelson. I tried to not read solutions as long as possible, but most exercises were awfully difficult to me, and the content itself was not easily digestible. When I tried to solve exercises in the chapter about m...

07:22
Can anyone recommend some other textbooks that can replace "Introduction to Mathematical Logic, 2nd edition" by Elliot Mendelson for me? It's too difficult for a math beginner.
user174558
@crocket Michael O'Leary: Mathematical Logic and Set Theory
1) what's the difference between phase space and parameter space
2) Is there a term for "a family of phase spaces"?
hi.. anyone know about matrix norms? math.stackexchange.com/questions/1517103/…
@Jasper ok
user174558
@crocket Mendelson is a good book, but it covers NBG set theory instead of ZFC which is the norm.
07:28
@Jasper Did you read Mendelson?
user174558
@crocket Parts of it.
Is it suitable for a person who knows some highschool math and read "how to prove it, 2nd edition" by velleman?
That's basically my background.
user174558
I think you would lack the background needed for Mendelson, maybe even O'Leary, maybe.
ah
ok
Tell me about the background
user174558
If you only know some high school math, why do you want formal logic?
07:30
I want to do ordinal logic which is handy in AIs.
user174558
Usually, people study lots of courses first like calculus before reading formal logic.
Mathematical logic is handy for AIs.
user174558
Formal logic is a third year course for math undergrads.
Is calculus a prerequisite for logic?
user174558
No, it is true that there are no prerequisites for logic, other than "mathematical maturity".
07:32
I'm a lone wolf living in a cave who studies alone.
user174558
I do not know about AI, but the O'Leary book is very elementary and you can try it.
user174558
But it is a little expensive, about 100 USD.
I could sort of understand what the author wanted to say about multi-valued logic, but the exercises on it are too difficult at my level.
But, it took an hour to read a page on multi-valued logic. It was that difficult.
user174558
Many exercises are difficult in a math book!
user174558
Well, I understand your difficulties since you are not a math undergrad.
07:34
The exercises can only be solved by very advanced ones.
Some exercises can be solved by me, but most are difficult.
user174558
@crocket I think you can go to wiley.com, see the first chapter of what I recommended, and see if it suits you.
@Jasper Well-said! Wait to see my book! :-)
user174558
@Chris'ssistheartist Hi! I have not met Laura Ramsey, LOL.
@Jasper :-)))))
@Jasper It's still not too late for doing that!
:D
@Jasper Did you refer to "A First Course in Mathematical Logic and Set Theory 1st Edition" by Michael O. Leary 2015?
07:36
so annoying that there aren't many dynamical system guys on chat lately, cause I have a stockpile of dynamical system related conceptual questions that need help on and there's isn't many people with the backgroudn that can help
user174558
@crocket Yes, I did.
A first course? Does it mean it's for me?
user174558
@crocket Titles in math books mean nothing.
user174558
@crocket Download the pdf file there, it has the first chapter.
@Jasper How do you know about the book?
user174558
07:43
@crocket Well, I found it online and read the first chapter like you did, that is all. And also looked at google preview and the contents page.
I can't find pdf
Where is it?
user174558
@crocket Click on "read an exerpt" on the Wiley page.
user174558
@crocket I am going out now, good luck.
user147690
@crocket For the record, taking an hour per page in a mathematics textbook, on content you have never seen before is quite normal
07:48
@AlexClark Do you think "Introduction to Mathematical Logic, 6th edition" by Mendelson is not suitable for me?
user147690
@crocket I don't know, I haven't read it, and I only skimmed the chat above
user147690
I am just saying not to be disheartened by moving through it very slowly
Is it totally normal to be unable to solve most exercises?
user147690
No, but mathematics it not at all like reading a book
user147690
You have to really think and keep trying
user147690
07:49
Try not to look at the solutions
I couldn't move a bit for half an hour with an exercise.
user147690
It'll become a necessary crutch very quickly
It is better to try than to think.
"Mathematics is not a spectator sport".
user147690
@crocket Sometimes I am stuck for two hours on an exercise
07:50
Sometimes I am stuck for days on difficult homework problems.
user147690
@crocket Sometimes a difficult homework has 3 questions and take me 3 weeks
user147690
Amen to that @9814072356
Perhaps, you should move on after trying for days or weeks.
If you are not going to build your career on top of only those problems.
user147690
@crocket Nah I always get it, and when I see something similar I can work it out very quickly in comparison
07:51
You look like an advanced student.
user147690
Not really
I study math alone at home.
As @AlexClark said. Often the best things in mathematics are hard won, and this requires persistence and effort (sometimes frustrating, but stick through it and you'll get it in the end)
user147690
Well take it from me, there are only 6 people left in pure math by final year at my university, and all of them have the same work ethic as I am talking about above
Rarely are things super easy, the more advanced you get
user147690
07:54
I mean, there is no reason why you should give up after 30 minutes, there is no law saying to give up, it means you are out of motivation, and you have to remember why you are studying what you are @crocket, which I imagine is something to do with working better on your problems relating to AI?
But, I feel that some books are unnecesasrily difficult for beginners.
user147690
Well unfortunately, often there isn't a nice book for beginners, I couldn't find one for hopf-algebras
Still, "Introduction to Mathematical Logic, Sixth edition" by Mendelson is too difficult for an entry.
user147690
I'll have a look, one sec
@crocket, it all sort of depends on how you define 'beginner'
07:56
I got a feeling that it makes concepts unneccesarily difficult.
user147690
Yes indeed, a beginner of the subject who hasn't got mathematical maturity will suffer
user147690
A beginner of the subject with mathematical maturity might find it easy
I know some highschool math and read "how to prove it, 2nd ed" by velleman. That's it
I have a bit of maturity
For example, Enderton's and I think Mendelson's that you mentioned, is targeted to late undergraduate maths students. Which is considered 'beginner', I think, with no prior exposure to the material
user147690
Well I would recommend to any human being to atleast read a few chapters of rudin's principles of mathematical analysis
07:58
<3 Rudin's
I'm like a freshman in a university.
user147690
Is that first year?
user147690
Freshman-> sophomore-> junior->senior?
(I have no idea, I'm not American)
oh, cool
sophomore goes in there somewhere?
user147690
07:59
Ahh forgot that one
Speaking of, I'm actually starting a seminar using Enderton's next term
freshman ! thats new term for me
(set theory) Debating between Jech's and Enderton's though, @AlexClark, have you used either of those?
user147690
We have no courses on logic :\ @9814072356
"A First Course in Mathematical Logic and Set Theory" by Michael O. Leary seems adequate for my level.
08:01
His set theory book, not formal logic, I think
user147690
No set theory or formal logic at my university
Jech's might go a bit fast, but Enderton's might be a bit slow. Hmm, something to think about
user147690
Wait wow, we will have one next year for the first time in years uq.edu.au/study/course.html?course_code=MATH3306
Ohh, that's a shame. We don't have an undergraduate course in that either, and the graduate one hasn't run for many years
its good to wake up the morning and learn new terms
08:02
interesting
user147690
@crocket Where are you in Mendelson?
user147690
The first chapter looks very standard first semester first year
"1.5 Independence: Many-Valued Logics" <-- This is difficult
I understood the chapter intuitively, but I couldn't solve the exercises there.
I do not have rigorous understanding yet
user147690
@crocket Well are you writing down stuff while you do the chapter?
user147690
08:05
@crocket Or just reading?
I write down solutions to exercises.
But, I just read content.
user147690
Well there is the first problem :p. You should be verifying things that are written on paper
I verify things in my mind.
user147690
Yeah that isn't enough
user147690
Otherwise everything seems good, and you forget it all immediately
user147690
08:07
It doesn't just seep into your brain
@AlexClark Exercises help me overcome illusion of competence, though.
The author sprinkles exercises everywhere to help with that.
user147690
You can't do the exercises without looking at the solutions
If verifying some claims about many-valued logic takes too much computation, I wouldn't do it
I'd rather hire a computer for that
It's not amenable to human computation.
My guess is that trying to solve exercises helps understand concepts even if I can't solve them.
user147690
Struggling does definitely help you understand what is going on, that's why some mathematicians hate computational 'proofs', since they lose all the intermediate information that is gained in actually doing the proof
I can't solve every exercise in the book because it'll take 4-5 years to read the book by solving every exercise I can.
Probably more than 4 years
I don't want to spend that much time on a book
From time to time, I could go back and solve some exercises.
user147690
08:13
Huh, there are ~370 pages, how much time do you have each day to dedicate to it?
2 hours a day
not more than that
user147690
You think doing every exercise you couldn't finish it within 3,000 hours of work?
user147690
That's 62 weeks of the recommended work frequency at university(doing 4 subjects), which is about 4 semesters of study
"A First Course in Mathematical Logic and Set Theory"
I study every day.
user147690
I think most people here do
08:21
@AlexanderGruber prolog is also needed as a mathematician
Now, I think the book I was reading is not really an introduction.
1
Q: Can you recommend a replacement for "Introduction to Mathematical Logic, Sixth Edition" by Mendelson for a neophyte?

crocketI started studying "Introduction to Mathematical Logic, Sixth Edition" by Elliot Mendelson. I tried to not read solutions as long as possible, but most exercises were awfully difficult to me, and the content itself was not easily digestible. When I tried to solve exercises in the chapter about m...

 
1 hour later…
09:30
People in Tex room are always really great!
09:55
@Chris'ssistheartist why do you say that?
@robjohn They are friendly, always answer back to you nicely and are really helpful. There is a positive attitudine in there you can easily perceive.
i see that this chatroom is the most helpful in se netwok
as it remains so (excluded trolls exhibitionists and haters)
how often do dynamical system background users visit this chat, because I have some chaos theory related questions but so far the users I have seen on chat are from an algebra background?
and ofcourse (moderators coming fom other planets just to apply their megalonania in a chatroom they r not elected moderator in)
10:23
Is there exist something more general than category theory?
10:46
https://en.wikipedia.org/wiki/Space_(mathematics)
what is the highest mathematical structure in the hierarchy that has a name?
More generally, what is the mathematical 'thing' that has category theory and multiset as special cases?
11:13
@Secret I am not sure I see any useful "thing" with that property
so the general consensus is that anything that is a generalisation of cateogry theory is expected to be not very useful?
@Secret depends on what you mean by generalization
something like "the inner product is a generalisation of the dot product of vectors in R^n"
"n dimensions is a generalisation of 3 dimensions", "an ideal is a generalisation of integers"

something along the lines of this...
I don't know if there's a term to describe this kind of generalisation but in mathematical education more abstract mathematical concepts are often introduce this way with motivational examples before giving definitions
such as how in most courses that taught about hilbert space it first start with vector spaces and inner products in $R^n$, $C^n$ etc. before the definitions are stated
@Secret You have seriously had courses on Hilbert spaces that did not presume knowing vector spaces?
nope
the hilbert space topic in our uni proceed in the usual way
however some uni taught hilbert spaces and other advanced topics like this:
http://www.math.lsa.umich.edu/~kesmith/infinite.pdf
they give some motivational exmaples in some spaces we encountered before as a stepping stone to the abstract definitions and axioms
that's the type of generslisation I am trying to ask
11:29
so put it in another way if there are lecture notes that is structured like the above link, but the topic is <the thing I want to ask what it is if there is one> and it uses concepts and theorems in category theory as motivational examples, then what would this <> be?
@Secret I can't think of anything like that. The usual "next step" after categories are some of the more specialized things in category theory like monads or $2$-categories and above. But these do not really have categories as a special case.
@Secret i dont know wheras u v pinged me or not but thats way over my head sorry
@Agawa001 O I was orignally trying to ask you about dynamical system users but right after the ping is sent, I realised you have left the chat thus I want to take back the ping later by deleting that message "which really only consist of the words (insert at symbol)Agawa001"

It seems the ping was still being sent , sorry for the confusion
@TobiasKildetoft I see, so category theory is pretty much the highest in the hierarchy of mathematical structure (in terms of generality) that mathematics community has a name for it?
@Secret Well, the highest that I can think of. There might be "higher" stuff that I am not aware of
11:37
(technically, semicategories are one such thing, they just don't seem to ever be studied)
@Secret Not sure what you mean by "highest in the hierarchy of mathematical structures". A category basically has no structure at all.
If you want something which has lesser structure, consider sets.
I thought the mophism arrows have given some kind of "structure" due to how it relates two mathematical objects together?
Morphisms have no structure.
In a general category, I mean.
i see
A category is just a set of objects such that for each pair of objects there is an associated proper class (plus a few desirable axioms). There's literally no structure assumed on a category.
The morphisms are just the elements of that proper class.
12:26
Hey is there a specific name for the torus embedded in $\mathbb{R}^3$
As opposed to the flat torus
there are several ways to embed a torus in R^3
if you mean the standard one, just say "standard embedding of the torus in R^3" :P
The standard one indeed
If you have any idea of how to solve the Helmoltz equation on it too that would be appreciated!
I am not familiar with the Helmoltz equation, sorry.
Laplace equation + a constant
Well $+ k y(x)$
I hardly know anything about differential equations, so I am not the right person to ask :)
12:31
I asked on stack exchange but so far not much luck :p
There's a known solution for toroidal coordinates but they don't seem to be directly related to the torus metric
Huy
Huy
@Slereah: Try MO?
Maybe
The overflows are a bit of a bother really
No automatic way to transfer questions
12:54
hi.. anyone know anything about matrix norms? math.stackexchange.com/questions/1517103/…
it would be great if someone could help

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