Mathematics - 2013-01-31 (page 3 of 4)

Tobias

15:00

@WouterZeldenthuis it has been too long since I learned about differentiable manifolds

Charlie

@skullpatrol no. remember what I said? If you go, I go too :)

skullpatrol

@Charlie This suspension was a comedy just like the movie Blazing saddles

Not a blaze of glory at all.

@Argon wazzup?

Argon

@skullpatrol Not much! Nice avatar, by the way!

@skullpatrol Haha I love that moive

skullpatrol

@Argon Thanks, and the movie was a classic too :-D

robjohn

@skullpatrol what comments were flagged?

skullpatrol

15:14

@robjohn Only 1 Sir.

robjohn

I didn't see anything deleted, nor anything worth flagging

I must have missed something somewhere

skullpatrol

The moderator approved the flag.

robjohn

@skullpatrol Do you know what was flagged?

Wouter Zeldenthuis

is $\gamma(t)=t^3$ a parametrization of $\mathbb{R}$?

skullpatrol

@robjohn Yes, I wrote it Sir.

Mad Scientist

15:21

@robjohn You can check on the chat user profile under "show all flags" if you know the user

skullpatrol

3 hours ago, by BenjaLim

@skullpatrol what do you do for a living?

It all started here (removed) is the beginning of the suspension.

user19161

Oh come on we are still talking about this?

user19161

What happened @skull?

robjohn

@MadScientist Yeah. Looking at what is listed there, I don't see anything worth banning skullpatroll

user19161

@amwhy I did not understand the proof Babak gave. Every line feels wrong.

Wouter Zeldenthuis

15:34

ah, the derivative is not 1-1. ok

skullpatrol

@JasonBourne I wrote one comment that got flagged and approved by a moderator.

user19161

@skullpatrol What did you write?

skullpatrol

@JasonBourne If I write it again it'll be life!

amWhy

which proof?

skullpatrol

@JasonBourne TPTB are watching, no?

user19161

15:36

@skullpatrol Oh well, never mind. A suspension is not a big deal. Even going to jail is not a big deal. That happens to many good people in this world.

user19161

@amWhy The one about the identity of the subgroup being that of the group.

amWhy

@JasonBourne I'll recheck it...

Garbage Collector

@JasonBourne: I have an animation for you i.sstatic.net/yx84R.gif

Charlie

You guys make a storm in a cup of water....

skullpatrol

Hi @GarbageCollector wazzup?

Garbage Collector

15:38

@skullpatrol Nothing. :-)

Charlie

@GarbageCollector HELLO!!!

user19161

@GarbageCollector Haha, thanks! By the way, was that girl in the photo you?

Garbage Collector

@Charlie Hi baby!

amWhy

@JasonBourne It's been deleted...

Garbage Collector

@JasonBourne oh my ghost!

user19161

15:39

@amWhy Yeah, because we can't assume that the identity of the group is in the subgroup from the start.

user19161

But maybe it is just his English.

user19161

@GarbageCollector So you won't answer that question? Well, that is alright. It is your secret!

Garbage Collector

@JasonBourne :-)

user19161

@GarbageCollector I think the answer to that question is yes. =)

Garbage Collector

@JasonBourne: :-)

@JasonBourne: You are interested in?

Novice

15:43

I have some very easy questions which are stupid for main.

user19161

@GarbageCollector What do you mean?

Garbage Collector

@JasonBourne I mean for any element of domain there is only one ... :-)

@JasonBourne: Gong Xi Fa Cai!

user19161

@GarbageCollector I have no idea what you are referring to now...

user19161

@GarbageCollector Haha, not yet...

robjohn

@Novice Although there is no level requirement for questions on main, some feel that if a question is too elementary, they need to downvote it. However, you can always ask here.

Novice

15:47

@robjohn Thank you.

Garbage Collector

Intermezzo: Today I got a message from my friend in facebook. It is a sad story. facebook.com/…

2

Novice

The question is: "Find the last digit in the expansion of $2^{12n} - 6^{4n}$". I tried $n = 0$ and it comes out to be $0$. But for the formalized approach, I know that it boils to showing that $2^{8n} - 3^{4n} \equiv 0 \pmod{10}$. Am I correct?

skullpatrol

@GarbageCollector That is not sad, but extremely disturbing...

Novice

Wait a sec.

Garbage Collector

@skullpatrol OK. Thanks for rephrasing.

David Toth

15:54

In algebraic topology, when attaching a cell to the skeleton, does an attachment map need be continuous?

skullpatrol

@GarbageCollector ...why would anyone do that?

Orange Harvester

@Novice Expand $2^{12}$ and $6^4$ and you shall get your answer.

robjohn

@Novice: $2^{12}=4096$ and $6^4=1296$ so $\bmod{10}$, both are equal. Raising them to the same power, they will still be equal.

Charlie

@skullpatrol ooooooh that is .... Disgusting.....Jesus Christ.....

Novice

Ah, yes.

Garbage Collector

15:56

@skullpatrol she might have mental problem.

robjohn

@Novice The same can be said for the last two digits.

skullpatrol

@Charlie I could not watch more than 5 seconds :'(

Novice

Thanks both for not pursuing the path "I Will Not Answer Questions If I Don't Get My Rep".

Garbage Collector

Who marked it with a star?

Charlie

@skullpatrol neither did I.... Horror....

skullpatrol

15:58

@GarbageCollector Not might but $\Huge\text{IS SICK}$

Garbage Collector

@skullpatrol Thank you for rephrasing again.

Novice

I have another question.

Never mind, figured it out.

skullpatrol

@GarbageCollector What chance does a child like that have of living?

Charlie

@skullpatrol that should get flagged...

skullpatrol

@Charlie You can flag reality all you want, but it won't change it, no?

Garbage Collector

16:03

@skullpatrol The baby probably will get disabled mentally and physically.

Charlie

@skullpatrol no

skullpatrol

@GarbageCollector Can you contact your friend who sent that?

Mistu4u

Hi everybody, Is it okay to ask a question on general approach to solve a specific type of problems if I can't get a good note on it online? Any ideas or advices?

Garbage Collector

@skullpatrol No. But I think it is searchable by the public.

skullpatrol

@GarbageCollector Please try and help.

Garbage Collector

16:06

@skullpatrol OK. I am searching...

skullpatrol

Thanks...

...for trying.

robjohn

@Mistu4u you can ask it here if you can't pose a good question on main.

Mistu4u

@robjohn, "main"??

robjohn

@Mistu4u the main Q&A forum

Mistu4u

Okkay. Thanks @robjohn.

skullpatrol

16:14

Nice formatting Sir :)

user19161

@robjohn Though I always believe that chat should be reserved for 1+1=2 and extended discussion. =)

robjohn

@Mistu4u If it is a good question for main, people here can help you with the wording for main

user19161

Yeah, once it gets to main, a million people will edit it.

skullpatrol

Not if the people in chat help word it correctly :)

robjohn

@JasonBourne yes, I am not saying that we take the place of main, but we can help with the simpler or longer discussions here. We can also help in figuring out how to ask a question on main

skullpatrol

16:17

Well said Sir.

user19161

Strictly speaking, we don't know the number of good oranges. There could be 150 bad oranges in the box. We can only give the estimated number of good oranges. — akkkk 10 mins ago

user19161

What does this mean? Can someone explain?

Garbage Collector

@skullpatrol: I cannot locate the persecutor.

skullpatrol

@GarbageCollector I feel better now that you tried, thanks again.

@JasonBourne Why don't you ask akkkk?

robjohn

@GarbageCollector you mean the person flagging comments?

Garbage Collector

16:22

@robjohn No. But the woman tortured the baby in the given video link above.

skullpatrol

Prepare yourself Sir $\Huge\text{:'''(}$

>8(

Garbage Collector

@skullpatrol Prepare for what?

robjohn

@GarbageCollector I didn't watch it yet

Novice

I am very stupid. How to factor $4a^2 + 9b^2 - 8a - 12b + 12ab$?

Garbage Collector

@robjohn Confirmed.

user19161

16:29

@Novice Regroup the terms first.

Novice

I see. $4a^2 - 8a + 12ab - 12b + 9b^2$

user19161

Not this way.

user19161

$4a^2+12ab+9b^2-8a-12b$

Novice

$4a^2 - 8a + 9ab + 3ab - 12b + 9b^2$

user19161

$(2a+3b)^2-4(2a+3b)$

Novice

16:31

Ah, got it

$(2a + 3b - 4)(2a + 3b)$

Thanks.

user19161

QED.

Garbage Collector

@JasonBourne Quantum Electro Dynamic.

user19161

Hello @reg why are you here?

RegDwighт

Is this a new meme?

Then this new meme sucks.

I can tell you.

user19161

I see you are here to see the video.

RegDwighт

16:36

I am here to bash physicists. Or was it physicians?

Wevs. They are our rivals.

skullpatrol

@Charlie are you OK?

Charlie

@GarbageCollector : D

@skullpatrol why you ask? I'm finee...

skullpatrol

@Charlie I'm still a bit shaky...

...that video caught me off guard :'(

Charlie

@skullpatrol that ... No one does anything... As a woman it bothers me a lot....

skullpatrol

$\Huge\text{Never let your guard down}$

robjohn

16:41

@skullpatrol what? I was buttering my toast... thwap

skullpatrol

@Charlie As a human being it bothers me a lot...

...what chance does the kid have of living?

David Wheeler

Physicists think pure math is unreal, therefore irrelevant. Mathematicians think physics is real, therefore, irrelevant.

skullpatrol

What do you think is what counts!

badp

Engineers don't give a fuck either way. Linearize all the things!

David Wheeler

i try very hard not to think. i may need those brain cells later.

Orange Harvester

16:45

@DavidWheeler That's not the problem, the problem is the device physics engineers performing numerical simulations squeezed in the middle. :P

David Wheeler

just do everything to O(n)

....according to my calculations that thing will hit the earth...plus or minus 3 AU....

2

Orange Harvester

:P

David Wheeler

here is how i factor polynomials: linear polynomials-ask a high-school kid to do it. quadratic polynomials: quadratic fromula (just add water). cubic polynomials: rational root test, then give up. all others: wolfram|alpha.

4

Orange Harvester

what does "fixing the proof of Rudin 2.43" mean? (it is not related to fixing the error)

David Wheeler

i was reading about perturbation theory yesterday...the gist i got from it was: well, if it's more than first-order, we just draw pictures.

context?

Orange Harvester

16:53

Show that the Cantor set is uncountable – either by fixing the proof of Rudin 2.43, or by using another (e.g. diagonal) argument.

user19161

Ladies and gentlemen I have 300 answers now...

David Wheeler

perhaps "adapting"?

Orange Harvester

`Hmm, yes that seems to be the thing. I thought may be it was some idiom I was not familiar with.

Today is David Wheeler's free star day.

robjohn

@JasonBourne Congrats

Orange Harvester

@JasonBourne good, now you can retire. :P

user19161

16:56

@OrangeHarvester Yes!

user19161

Sometimes, the way to carry on is to give up.

David Wheeler

what do the green check-marks mean?

user19161

Acceptance.

user19161

Gives asker 2 points and answer 15 points.

David Wheeler

oh. so that's why my rep is going up. must. make. more. mistakes.

i know how to get banned on this site...just ask a question about infinite sets, and bash everyone who answers. i could so do that.

especially asaf. he's so easy to upset.

i should call this posting technique "forcing". oh, the irony.

user19161

17:01

I think different people are upset by different things.

user19161

It's determined a lot by our life experiences.

David Wheeler

i kno rite? for example, you could call me ugly and i wouldn't care. but call me unkewl, them fightin wurds.

RegDwighт

David Wheeler is totally uncuil. He only uses google.

David Wheeler

zomg! untroo! i use bing too.

RegDwighт

Oh, and that makes you cool, how?

Orange Harvester

17:04

@RegDwighт Duckduckgo makes you cool?

David Wheeler

the ad promised it would.

RegDwighт

@OrangeHarvester Duckduckgo makes you exactly nothing except a Duckduckgo user.

@skullpatrol what? Bing? Sure thing I saw it.

Orange Harvester

@RegDwighт seems correct.

David Wheeler

zomg! reg haz a tau in his handle. 10-4 big buddy.

RegDwighт

That is not a tau. You're becoming uncooler by the minute.

David Wheeler

17:06

upside-down perp sign? even more rad.

RegDwighт

That is a Т.

David Wheeler

why so srs?

RegDwighт

You can copy it into a Wikipedia search box.

Sorry, I meant the Bing search box.

Except the former will actually work.

skullpatrol

@RegDwighт Are you Canadian, is that why you chose a beaver for a gravatar?

RegDwighт

@DavidWheeler I am getting paid several bundles of sponduli per very few units of time to be just that, serious.

@skullpatrol first of all, that's an American Beaver.

No really, he is.

Second of all, I used to be an owl. And a viscacha.

David Wheeler

17:09

wikipedia (which is, after all surely as reputable and reliable as the OED, or brittanica) says its cyrillic or some such

RegDwighт

See, Wikipedia is always right.

QED

David Wheeler

quasi-erudition done!

skullpatrol

Charlie

@RegDwighт that's a nice beaver

David Wheeler

now excuse me while i google sponduli

RegDwighт

17:10

Good luck with that.

skullpatrol

@Charlie Don't you like my viscasha?

David Wheeler

apparently a reference to Conker's Bad Fur Day

Charlie

@skullpatrol yes!

RegDwighт

Meanwhile Jasper right there will tell you that I used to be RegDwight, RegDwight Ѭſ道, RegDwight βßВ8, RegDwight ΒВB, RegDwight АΑA, and ЯegDwight, but people kept complaining they couldn't ping me.

David Wheeler

sounds like something out of the sopranos tho, tbh

skullpatrol

17:14

@Charlie I really need to see something cute right now.

RegDwighт

@DavidWheeler you know what, Conker does use the word exactly once, after fighting Sloprano.

skullpatrol

Hi @BrianM.Scott how are you?

RegDwighт

►

Charlie

@skullpatrol awn behind this skull beats a warm heart

Brian M. Scott

@skullpatrol Frustrated. I despise what’s been done to the main Question page.

skullpatrol

17:16

Only when I let my guard down :P @Charlie
@BrianM.Scott What are they doing?

David Wheeler

oh noes! what terrible things have come to pass?

RegDwighт

El Pas, New Mexico?

Novice

Good day, @BrianM.Scott. It's been a while.

Brian M. Scott

@skullpatrol Posting to it every time someone posts or edits an answer (or possibly even a comment $-$ I’m not sure about that).

RegDwighт

Um. It's not always been that way on Maths?

skullpatrol

17:17

@BrianM.Scott That is a lot of change.

RegDwighт

It's always been that way on every other SE site ever.

Brian M. Scott

@RegDwighт No. A question has always appeared on the main Questions page once, when it was first posted.

RegDwighт

@BrianM.Scott and never bumped to it again? You sure?

That would require a change to the engine just for this one site.

Brian M. Scott

@RegDwighт I don’t know about never, but certainly not every time someone posts an answer.

RegDwighт

How did you get to know that someone did post an answer, then?

badp

17:19

@BrianM.Scott That has never been the case since Stack Overflow launched as a standalone site in 2009

Brian M. Scott

@RegDwighт Update the Question page and check the number of posted answers.

badp

Maybe you're thinking of Math Overflow or other SE-alike engines?

RegDwighт

Yeah I'm scratching my head in disbelief as well.

badp

although I'm fairly certain MO bumps as well

Brian M. Scott

@badp It has been the case as long as I’ve been answering questions on MSE, which is over a year and a half.

badp

17:20

At any rate @BrianM.Scott if you just want a list of questions as they're asked without bumping, you can consider using RSS

RegDwighт

@BrianM.Scott how did you know that the number had changed? You kept tabs on every question ever?

badp

@BrianM.Scott I am fairly certain you are either mistaken or you weren't using the default sort order

Brian M. Scott

@RegDwighт I can tell whether it’s $0$ or not, which is usually the most I care about.

badp

Maybe you were using http://math.stackexchange.com/questions?sort=newest ?

RegDwighт

@badp Yeah, was just going to point out that. He's probably looking at some other tab.

skullpatrol

17:21

@BrianM.Scott Have you heard this?

Novice

I recall myself learning how to multiply two three-digit numbers in the fifth grade. Who in the world does diophantine equations with five variables when one doesn't know how numbers work?!

RegDwighт

That cookie that remembers your preference sure is a source of a helluvalot of confusion.

Brian wouldn't be the first.

Brian M. Scott

@badp Thank you: your comment about default sort order made me check, and sure enough, I must inadvertently have set it to active instead of newest. Sanity is now restored.

badp

(and never click on the "new questions" autoupdating thing)

RegDwighт

Well, another day saved by badp!

I must be off for a Spieleabend anyway.

badp

17:22

Days saved by badp: 0,001

skullpatrol

Days ruined ?

RegDwighт

Days badp has been hated to death by ЯegDwight: 1.

Ouvert et haut !

badp

@skullpatrol 0,002×10³

Novice

Days I have been ignored on this chat: ∞

skullpatrol

Congrats.

badp

17:23

although we moderators usually use the milliHitler as the unit of reference for this kind of query ;)

Charlie

@Novice don't cry,, Parth

Brian M. Scott

@Novice Sorry about that: I got involved in the other business and forgot to respond.

Novice

@Charlie OK, ∞ - 1. But that's still ∞.

Ugh -- I do not cry for attention.

badp

@Novice That's a number theory I wasn't previously aware of :P

Brian M. Scott

@badp Works fine with surreal numbers.

skullpatrol

17:25

@Novice Come on palio, show us what you got.

savick01

Hello there. Is it true, that for $c\in mathbb{C}$ and its minimal polynomial $f\in \mathbb{Q}[x]$, all the roots of $f$ have the same module? It seems that my lecturer used it in his proof, but I don't think it's true...

Novice

@badp It doesn't matter if you remove a star from the Universe.

badp

@Novice It creates quite a lot of turmoil actually in that portion of Universe, actually

skullpatrol

actually?

badp

actually

David Wheeler

17:27

i've never been able to actually remove any stars, i wouldn't know

Novice

@badp Yes, it gets the mathematicians crazy after that idea.

badp

For example, at some point in the next few thousand years, Betelgeuse should remove itself from the list of stars (afaik) and shine almost-sun-level light for a week straight

David Wheeler

@savick01 what do you mean by "the same module"?

Brian M. Scott

@Novice: You should change your last name to Galen. :-)

badp

If live on this planet will still be a thing, that'll bring distress to quite a lot of chickens, who will be driven mad by the lack of sleep and cross the street. Bringing finally the definitive answer to this ages-old question:

Why did the chicken cross the street? Betelgeuse exploded.

savick01

17:28

@DavidWheeler for $a+bi$ the module is $\sqrt{a^2+b^2}$, where $a,b$ are real

Novice

@BrianM.Scott Wow. You remember names!

David Wheeler

oh modulus!

savick01

Oh, sorry:D

Brian M. Scott

@Novice Sometimes. But yes, I did remember yours.

skullpatrol

Hi @Argon welcome back!

Argon

17:30

@skullpatrol 'ello!

user19161

The trick to answering ambiguous questions is to take care of all possibilities in a self-contained answer.

badp

"Hi, what xy do?"

skullpatrol

The trick to answering ambiguous questions is to answer the question you think should have been asked QED

user19161

That might get you downvoted very quickly.

badp

@JasonBourne I sure hope it does!

Brian M. Scott

17:33

@skullpatrol I hadn’t; I’ve almost never looked at the blog.

badp

I say ambiguous questions should be commented upon until they're no longer ambiguous

skullpatrol

@BrianM.Scott I can't believe how fast they talk!

Brian M. Scott

@skullpatrol I didn’t actually listen: I just read the transcript.

savick01

@badp I think that's much better than writing a useless answer or writing a few times more than necessary

Charlie

@skullpatrol true

skullpatrol

17:35

@Charlie Thanks :)

Brian M. Scott

@badp I’m willing to close them eventually if the OP doesn’t respond at all to comments.

badp

@BrianM.Scott Sounds healthy :)

Charlie

@skullpatrol ;)

skullpatrol

@Charlie ;-D

savick01

Guys, any idea about my question about roots of a minimal polynomial?

user19161

17:38

I think I know why someone wasn't happy with my proof yesterday that $a!b!$ divides $(a+b)!$.

user19161

I used A implies B to prove B from A. But they thought that I needed B to prove A so that it was circular.

user19161

I thought about it and it is not truly circular. However, there is some pseudocircularity there.

savick01

pseudocircularity :D

user19161

That is because when I used A although B wasn't needed to prove it, B is an intermediate result that arose naturally in the canonical proof of A.

user19161

So I have edited my answer accordingly to remove that pseudocircularity.

skullpatrol

17:41

Is an ellipse "pseudocircular?"

user19161

You know the above meta-analysis is even more complicated than the proof itself.

user19161

That is why logicians can go nuts, like Godel.

Novice

Unable to find math.stackexchange.com?

skullpatrol

wth^

badp

loads for me

Brian M. Scott

17:43

@skullpatrol Nah, it’s circular: you just have to look at it from the right angle.

skullpatrol

true dat^

@BrianM.Scott A circle is not psuedoelliptical if you look at it from the right angle?

Brian M. Scott

I just noticed: we’re almost in sight of $10000$ problems tagged (homework)! (We’re at $9800$.)

badp

pseudocircle

Brian M. Scott

@skullpatrol No, it’s elliptical. Clearly, then, elliptical = circular!

@badp Potato.

badp

@BrianM.Scott Pseudosphere.

Novice

17:47

@BrianM.Scott That's a lot of homework though.

Charlie

@badp it's a true potato!

Brian M. Scott

@Novice ’Tis indeed. Especially since I’m sure that we’ve seen quite a bit of homework that wasn’t tagged as such.

skullpatrol

@Charlie Define "true?"

badp

It's certainly not photoshopped

skullpatrol

Would that make it "psuedo?"

Brian M. Scott

17:49

@skullpatrol Not false. Not, for instance, the false-potato that grew on Hades in David Weber’s Honor Harrington novels.

Charlie

@skullpatrol that approximates what many can observe, real,

skullpatrol

hmmm...

Brian M. Scott

@Charlie Maybe it’s a faithful potato.

skullpatrol

faith?

sounds...soo belief based, no?

Brian M. Scott

@skullpatrol One meaning of true is faithful, loyal.

user19161

17:53

I shall repeat my favourite words on faith, from myself.

skullpatrol

@BrianM.Scott or so you would like to believe...

user19161

Faith is not truth. Evidence is not proof. Evidence leads to faith. Proof leads to truth.

Argon

What is truth without faith?

skullpatrol

...proper justification leads to a properly justified true belief. QED.

user19161

Religion is about evidence and faith. Mathematics is about proof and truth.

Brian M. Scott

17:56

@skullpatrol That’s actually the oldest meaning of the word, which is from Proto-Germanic $^*\text{trewwj-}$ 'having or characterized by good faith'.

user19161

The existence of deities may not be provable, but neither is it disprovable. One then chooses to believe in them or not based on selecting evidence for or against.

user19161

Therefore, religion is not rubbish, contrary to the flawed logic of pseudo-intellectuals.

Transcript for

$Mathematics$ Mathematics