Mathematics - 2014-11-17 (page 2 of 6)

r9m

04:13

@skull turned pink ?! :-)

skullpatrol

@r9m until my team wins, yes >8(

0-10

Zach Saucier

What would a physical interpretation of $\int_{C} δ\hat F \cdot \hat n ds$ be where the density of the fluid at each point of the plane is given by a function δ? My guess is the mass because density * volume, but since it's varying I'm not sure

r9m

@skullpatrol o?~! which game(sports?) are we talking 'bout ? :)

skullpatrol

@r9m NFL

@r9m American Football

r9m

@skullpatrol oho !! playing bets ?! pink was the price ? or was it by decision ? :)

skullpatrol

04:24

@r9m pink is a girls' color, so until they win they are playing like girls

imo

r9m

@skullpatrol haha :D okay !!

skullpatrol

:D

Mike Miller

04:38

hi @Ted

Ted Shifrin

Aren't you ignoring me too, @Mike?

Kaj Hansen

No one listens to @Ted :P

Mike Miller

Of course not!

Ted Shifrin

@Mike, did you tell Jacob you liked his talk?

Mike Miller

Of course.

skullpatrol

04:44

Hi Professor @TedShifrin

Ted Shifrin

then I guess he figured out my "source" 😛

Hi pink @skull

Mike Miller

How many people at UCLA talk to you? I can't imagine it was very hard. :P

Ted Shifrin

The Tao appearance on Colbert was pretty stupid.

Mike Miller

Yeah.

His send-off joke was really, really funny though.

Ted Shifrin

He seemed incredibly ill at ease, too.

Mike Miller

04:47

It was a pointless interview. I don't understand why Colbert invites someone that he's not going to engage with.

Jasper Loy

Why are @MikeMiller and @ZachSaucier ignoring @PedroTamaroff as written?

Zach Saucier

we're not :P

Ted Shifrin

all humor and no content ...

skullpatrol

a tv personality he is not

Mike Miller

Ah well, just another attempt to engage the public about math that didn't do so hot.

Kaj Hansen

04:48

I always set my expectations low, and so I wasn't disappointed.

Ted Shifrin

Same reason you're ignoring me, @Jasper :)

Jasper Loy

6 weeks to the new year, I am very excited.

@TedShifrin I was a little upset about you yesterday, but I am fine now. =)

skullpatrol

Orly?

Ted Shifrin

That explains a lot, @Kaj.

Mike Miller

How kind

Jasper Loy

04:50

The past few months I have mostly switched from tea to coffee.

Kaj Hansen

Like positive course evaluations?

kidding

Mike Miller

ouch @Kaj...

Ted Shifrin

I have made several people upset with my bluntness recently, but in the end what I've said was truthful and honest and needed to be said. More reason to retire :)

Mike Miller

:(

Jasper Loy

I am now thinking of using Assimil to learn languages. But the books are quite expensive and they are undergoing a revision.

Ted Shifrin

04:54

You do expect little from courses, @Kaj. 😁

Kaj Hansen

So long as 35XX doesn't end up going the way of 24XX @TedShifrin

Mike Miller

what're those

Jasper Loy

I am very sad in my country. I should move to Antarctica and live alone.

Ted Shifrin

@Kaj, I created and then taught 2400 13 times, and the last 2 it was clear to me death was imminent.

Kaj Hansen

@MikeMiller, 24XX was a more theory-oriented first/second semester calc sequence at UGA that was taught out of Spivak. Ended up dying off since too few people were registering for it.

The Artist

04:55

@Committingtoachallenge Monash or University of Adelaide? Which one would you recommend...

Mike Miller

That's awful.

Ted Shifrin

@Jasper, your personal issues notwithstanding, the world is a very f*****- up place.

Jasper Loy

@TedShifrin Yes, it is. Sometimes, I wish I could rule the world. I will make it a much better place.

The Artist

@JasperLoy where are you from? :)

Ted Shifrin

It died at Berkeley and Rice over a decade ago, @Kaj

Jasper Loy

04:57

@TheArtist It is a secret, for secret reasons.

Mike Miller

@Ted The analysis course at SCU in my senior year had to be turned into an independent study because only 3 people signed up.

The Artist

@JasperLoy oh ok :)

Kaj Hansen

Do you think it has a lot to do with AP becoming more widespread @Ted? And thus more people skipping right into multivariable? I know that was the case for me.

Jasper Loy

@TedShifrin Rice is what I eat every day.

Ted Shifrin

Yes, BC Calc is an insidious disease, @Kaj. Plus people not wanting a challenge (why 3500 shrinks by 1/2).

user61230

05:00

(It gets worse. My high school taught Calc III.)

Mike Miller

The only reason SCU math students still learn some theory is because the diploma requires it.

Ted Shifrin

Math is a growing major, @Mike, but most places on the applied sides.

Jasper Loy

I think it is better not to learn calculus than to learn it too improperly first.

skullpatrol

whoever thought of this AB BC thing?

Ted Shifrin

i have students who took so-called calc III in high school. They don't learn much and they don't get college credit. Shrug.

Jasper Loy

05:02

Calculus is still part of the standard high school syllabus here, but it is only a little.

user61230

I mean, to be fair, when I compare how I was taught to what's strictly written on a syllabus here, it's much the same. It's just the way through which it was taught that doesn't sit well with me.

Ted Shifrin

@Jasper: Most people don't learn things until they see them a second time.

Zach Saucier

42 mins ago, by Zach Saucier

What would a physical interpretation of $\int_{C} δ\hat F \cdot \hat n ds$ be where the density of the fluid at each point of the plane is given by a function δ? My guess is the mass because density * volume, but since it's varying I'm not sure

Kaj Hansen

Eh, I learned enough calculus to get a 5 on the AP exam, but I don't feel like I've learned calculus.

Ted Shifrin

even college faculty mostly teach calc 3 badly. Lots of mathematicians don't understand it well.

Mike Miller

05:03

I don't know calculus, and they're having me teach it.

Karl Kronenfeld

@TedShifrin What are some signs of a poorly taught calc 3 course?

Ted Shifrin

if $F$ is velocity, the flux is rate of mass transport across the curve, @Zach.

user61230

What I'm looking for is a source to learn calculus from that starts from $\epsilon-\delta$ and works up from there.

user61230

And the sad thing is, I'm not finding it.

Ted Shifrin

I'll rant about it some other time, @Karl.

Karl Kronenfeld

05:05

:)

I am genuinely interested though

Jasper Loy

Is Merriam Webster the most popular dictionary in the US?

Ted Shifrin

Try Spivak plus my Multivariable math book, @Emrakul :)

Kaj Hansen

People don't use dictionaries anymore, tbh @JasperLoy

Karl Kronenfeld

dictionary is now strictly a programming term

user61230

@Ted Of course you'd want me to buy your book ;)

Ted Shifrin

05:07

don't buy. Libraries still exist.

user61230

...huh, I wonder if my library has it, then.

Jasper Loy

@KajHansen OK, I am obsessed with books, as you know.

Ted Shifrin

Second choice is Apostol Calculus vols 1 and 2 ...but for various reasons I prefer the first choice.

Zach Saucier

@JasperLoy I'd say it used to be

but Kaj is right, not many people use dictionaries anymore

Ted Shifrin

I still like American Heritage Dictionary ...

Zach Saucier

05:09

unless they're translating to a foreign language with a dictionary

Kaj Hansen

@TedShifrin, that's actually the dictionary I own

Ted Shifrin

ok, g'night, all.

Zach Saucier

@TedShifrin sleep well!

Kaj Hansen

We'll misbehave without you :D

Twink

@AlexanderGruber Thank you, you're doing a great job as a moderator, specially for banning me from the chat for 30 minutes for no reason.

Jasper Loy

05:10

Here comes @twink, lol.

2

@Twink How did you know it was him? It could be automatic.

Twink

it wasn't automatic

and he had previosly accepted that he deleted one of my comments

just because some people flagged it

Mike Miller

If enough people flag a comment, you're banned from chat for 30 minutes.

Jasper Loy

@Twink What did you say this time?

Zach Saucier

^^

Mike Miller

This is unrelated to whether or not a moderator deletes your comment, even.

Zach Saucier

05:12

longer for the second time

Twink

@JasperLoy I don't think I should repeat it

Jasper Loy

@Twink I have been banned from chat 5 times. It is not a big deal.

Twink

people is so sensitive these days

skullpatrol

hi pal

Twink

I guess they're on their days

hi pal @skullpatrol

Jasper Loy

05:13

I have also been arrested by the police before.

Twink

@JasperLoy why?

Jasper Loy

@Twink I did something wrong, but it is a secret.

Twink

come on, tell us

we'll keep the secret

Alexander Gruber

@Twink huh? I didn't ban you from chat.

Jasper Loy

Well, I shoplifted, but when I was very young. They let me off later on.

skullpatrol

05:15

huh? They took me to court :(

Twink

Every kid shoplifted at least once

Jasper Loy

Did you go to jail?

Twink

@skullpatrol why pal?

skullpatrol

@Twink shoplifting

Twink

are you sure?

skullpatrol

05:16

yes

Jasper Loy

However, what I am thinking of doing these days is not wrong, but I still could be arrested.

Twink

tell me the truth

Jasper Loy

Now that is a real secret.

Twink

what are you thinking of doing @JasperLoy?

Jasper Loy

@Twink No, killing someone is wrong.

skullpatrol

05:17

@Twink he is sure, the system does it, automatically for certain words

Twink

pal, I said that word before, and the mod just removed it

but I wasn't banned automatically

skullpatrol

so the system counts

Twink

the second time I wrote the word, the mod banned me

skullpatrol

second offense etc

Alexander Gruber

I'm right here, @Twink. you don't have to refer to me in the third person.

Twink

05:19

I wasn't banned automatically

and it was the third time

I'm sure someone banned me

a person, not the system

skullpatrol

gringo

Twink

well, @AlexanderGruber since you said you didn't banned me, I don't know who did it

Alexander Gruber

shrug could have been another mod, idk. That doesn't mean I won't suspend you in the future if you break rules.

Twink

that's why i refer to that person as the mod

skullpatrol

gringo

see^ I'm on your side pal

Mike Miller

05:20

@Twink when you're flagged by five users, you're banned for half an hour. I wouldn't quite call that the system but it's not a moderator either. when alex deleted your comment he said it had a number of flags.

Twink

there you go @AlexanderGruber, now you threaten me for no reason, good job.

Alexander Gruber

@Twink I'm just tellin you the facts, bud.

I am a lenient mod in this chat. most people don't realize I am one, because I don't do very much of it

Twink

considereing the fact that I already know that I will be banned if i break the rules

skullpatrol

@Twink nobody is threatening my pal

Mike Miller

i don't think i've ever seen a chat moderator actually do stuff here

Alexander Gruber

05:21

but that doesn't mean that I can ignore flags

Mike Miller

@AlexanderGruber does it show you who flags stuff?

Twink

you don't need to tell me that

Alexander Gruber

@MikeMiller it doesn't directly but i think i can find that if I dig around a little bit

Twink

when I said the word for the first time, 5 pepole flagged the comment, I know that because @AlexanderGruber said that, and I wasn't banned by the system, he just removed my comment

so I don't think I was banned by the system

skullpatrol

ok ok

Twink

05:23

someone banned me, and I'm not saying it was @AlexanderGruber

could have been another mod

skullpatrol

let it go pal

who cares

Twink

I do

skullpatrol

why?

Alexander Gruber

in any case, one thing you should know is that every mod from any SE site can moderate every chat

Twink

because I was banned for no reason

skullpatrol

05:24

so have I

Alexander Gruber

and they can also see every flagged comment, even if they are in another room

Twink

and I'm a drama queen

and you're not, pal

Alexander Gruber

so it's not just the math.se mods that do things in this room

Twink

that's the difference

skullpatrol

:D

Twink

05:25

I know that @AlexanderGruber, I was banned for 7 days once by a mod from an English chatroom

and I wasn't able to enter any chat

skullpatrol

i remember

Twink

you do?

skullpatrol

that was unfair

Twink

it was someone with a picture of a demon

skullpatrol

but they are mean in there

Twink

05:26

I don't even remember what was the reason why he banned me, but it was ridiculous

skullpatrol

they gang up on people

and then they laugh about it

Twink

where is Jasper?

is he online?

skullpatrol

I like when they try to gang up on me

I just use the ignore button on all of them

dunno

@Twink see ya later pal

Twink

@skullpatrol bye pal.

Kaj Hansen

05:52

....What is going on?

Jasper Loy

@KajHansen Drama, lol.

Kaj Hansen

How on earth does drama arise on a math chat? I guess I'll go back to my analysis...

2

Jasper Loy

@KajHansen What book are you using?

Kaj Hansen

@JasperLoy Rudin's PMA

Rafflesia arnoldii

06:40

Anyone wants to weigh in on this Real World Application of math? (At Home Improvement site):

5

Q: How do I calculate the length of a ladder I need to reach a certain height?

My roof-line is 24' from the ground. What length ladder should I purchase to ensure I can reach the this height safely? I'm guessing there is a "safe" angle (a) for a ladder, regardless of the height (h). So more generally what is an easy way to calculate the length of a ladder (l) to safely r...

ladder

Mike Miller

I firmly agree with the guy decrying the use of math here.

Twink

Does anyone know if this is true?: Let $H$ be a Hilbert space and $S, T$ be bounded operators on $H$. Then $\langle Tx, y \rangle = \langle Sx, y\rangle$ for all $x, y \in H$ implies $S=T$.

Mike Miller

06:56

yes; because then $\langle (S-T)x,y\rangle = 0$ for all $x,y$; now take $y = (S-T)x$ to see that $Sx=Tx$

Twink

@MikeMiller Thank you :D

cxseven

so the operators don't need to be bounded

Twink

@cxseven I guess not, and also $H$ doesn't need to be complete

cxseven

is there an everywhere differentiable function $f: \mathbb{R}^n \rightarrow \mathbb{R}^n$ such that its Jacobian determinant is never zero, but is positive at one point and negative at another?

Twink

It's just that that's what I'm working with

Anthony

07:13

@MikeMiller!

Mike Miller

hi Anthony

Anthony

How goes your research?

Or have you even started yet?

I know nothing of graduate students.

Mike Miller

It doesn't and no

I've only an idea about the field it'll be in

Anthony

I see.

Are you buds with Terence?

Mike Miller

Nope.

Anthony

07:18

Awh.

Mike Miller

eh

@cxseven I suspect the answer is yes. Play with the standard examples of everywhere differentiable functions that don't have a continuous derivative.

cxseven

Terence actually posted something about this and when he was asked for an example, didn't reply

63

Q: Does the inverse function theorem hold for everywhere differentiable maps?

(This question was posed to me by a colleague; I was unable to answer it, so am posing it here instead.) Let $f: {\bf R}^n \to {\bf R}^n$ be an everywhere differentiable map, and suppose that at each point $x_0 \in {\bf R}^n$, the derivative $Df(x_0)$ is nonsingular (i.e. has non-zero determinan...

ca.analysis-and-odes gn.general-topology

Mike Miller

not so surprising he isn't responding to comments on years-old posts :P

Anthony

07:34

Is there some kind of geometric reason why the Fourier transform isn't unitary?

Mike Miller

prolly

Anthony

Well from time to angular frequency. I realized there's the $2\pi$, but to renormalize I think you use $\frac{1}{\sqrt{2\pi}}$....

Mike Miller

I'm no help here

Anthony

Yeah it's alright. Hopefully someone will see.

robjohn

07:51

@Anthony what do you mean by unitary?

Anthony

I was just reading wikipedia, I'm actually a little confused at the moment.

Twink

you're the one.. you're the policeman?

robjohn

@Anthony does Wikipedia say this?

Anthony

It says that you need to split the $\sqrt{2\pi}$ to stay unitary

Twink

what is your job?

Anthony

07:53

Who are you talking to?

Twink

no, you are the one

Anthony

...

Twink

why are you so upset?

Anthony

I still don't know if you were talking to me.

robjohn

@Anthony That depends on how you define the Fourier Transform... If you define it as $$\int_{\mathbb{R}}f(x)\,e^{-2\pi ix\xi}\,\mathrm{d}x$$ then it is

Anthony

07:54

That integrand.

:P

Twink

do you know where i am?

Anthony

Ah. @robjohn So I mean to use angular frequency instead of frequency, so you get the factor of $2\pi$.

robjohn

@Anthony The inverse transform of that is $$\int_{\mathbb{R}}f(x)\,e^{2\pi ix\xi}\,\mathrm{d}x$$

Anthony

Indeed.

Twink

i am at work

►

Anthony

07:57

@robjohn Why are unitary operators isometries?

Oh nevermind, that's easy.

Twink

by definition

Anthony

That's so strange.

Adjoints are strange beasts.

Twink

Mike Miller

08:29

@Rafflesiaarnoldii I have my doubts that question you answered that I just commented on (re: closed forms of $\zeta$) was asked in good faith.

Twink

@MikeMiller can you please help me to understand something about integrals with respect to a complex measure?

Anthony Carapetis

09:07

anyone know why "continuous semigroups" are called semigroups and not monoids?

Jasper Loy

Aren't monoids different from semigroups?

The Artist

09:23

@JasperLoy @robjohn I need a lil bit of advice :) In my question : math.stackexchange.com/questions/1018672/…

Jasper Loy

@TheArtist I have forgotten all my math. I am only a banana.

The Artist

@robjohn please take a look at the commenter Alex.H on the accepted answer

@robjohn Is he correct or am I correct? Should I listen to him?

@JasperLoy It's not about math

I mean even new readers, if they don't understand the accepted answer they can all look down to see other perfect answers. He's talking like users answer questions to make it accepted. @robjohn Help center tells me Im right. Tell me if I'm wrong, I will accept a different answer :)

Jasper Loy

@TheArtist It is about math, lol.

The Artist

@JasperLoy It's about a user telling me about site rules :p

Anthony Carapetis

09:42

@JasperLoy: yes, a monoid is a semigroup with identity

and part of the definition of a "continuous semigroup" (really a kind of representation) specifically refers to identity

Integrator

09:53

Who is Rafflesia Arnoldii?

Integrator

10:08

@robjohn My comment was deleted from this answer (From meta) may I please get to know the reason.

Nick

11:15

I'm on a search for Emirps with added mirror properties! Can you find one?

7

Q: Sheldon Cooper Primes

On the $73^{\text{rd}}$ episode of the Big Bang Theory, Dr. Sheldon Cooper, an astrophysicist portrayed by Jim Parsons $(1973 - \stackrel{\text{hopefully}}{2073})$ revealed his favorite number to be the sexy prime $73$ Sheldon : "The best number is $73$. Why? $73$ is the $21^{\text{s...

prime-numbers recreational-mathematics

$73$ is the largest known one less than $100,000$

Hippalectryon

@PedroTamaroff Im my exercise sheet it's tagged as a mean one after all :)

Sawarnik

11:59

@Nick @Nick @Nick !

@Integrator What was your comment?

Rafflesia arnoldii

12:23

@MikeMiller I deleted the CW "answer", since there is another one posted now. The question looks odd, but the user has nontrivial activity on SO with reasonable contributions, so perhaps it's just that: an odd-looking amateur question.

dorothy

12:43

hi

I would like to add a bounty to math.stackexchange.com/questions/1023351/… but I don't see the "x hours left " thing at all

do I not have enough rep?

Nick

@Sawarnik yes, yes, yes?

Sawarnik

@Nick Hillo. Still here/

Nick

@Sawarnik A hello to you too. How are you today? ;D

Sawarnik

:D

@Nick Do you eat rice with hands too?

robjohn

@TheArtist You can accept whatever answer helped you the most.

Sawarnik

12:58

@Nick Great :D

Nick

@Sawarnik I try to avoid it but yes, generally at home.

Sawarnik

@Nick Avoid it where?

Nick

anywhere else I'd have to eat at, like at school, a friends house or at a restaurant.

i don't think eating rice and curd two to three times a day is good for one's metabolism. There are loads of other stuff I'd prefer as meals.

:18642165 That is stereotypical thinking of stereotypical thinking. Dang, now I'm doing it.

Sawarnik

@Nick I eat once during a heavy lunch .. rest of the times its roti.

skullpatrol

i suppose if your hands are perfectly clean

Sawarnik

13:02

@Nick Is roti eaten in Kerela?

skullpatrol

roti is eaten by hand

chop sticks are too small

Nick

@skullpatrol It's wet food, if you have rice, you have to add some curry/thoran and roll into a ball before you put it into your mouth.\

skullpatrol

icic

Nick

@Sawarnik I eat roti, I prefer naan or chappathi. For some reason I always end up eating parrotas and egg roast at a local diner.

Sawarnik

@Nick Aren't they too oily-type? I prefer plain simple rotis.

Nick

13:07

@skullpatrol My point was if you're indulging in such a practice, washing your hands properly becomes a subconscious sense.

Sawarnik

@Nick That's not a very great choice :/

Nick

@Sawarnik Yes, a bit. But I don't like those hard, dehydrated crunchy rottis.

@Sawarnik I know, I know, but it's once in a while.

Sawarnik

No, not dehydrated, fresh :D

@Nick Philae.

Nick

@Sawarnik Well, I love fresh warm rottis. Haven't had one in ages though.

Sawarnik

:O Y?

@Nick true.

robjohn

13:15

@Integrator You had deleted a number of comments and the comments remaining seemed to be off-topic so they were deleted. Your comment that was not deleted by you was not about the question but about a particular user's voting habits.

skullpatrol

Blog - Stack Exchange: Stack Overflow: Where We Hate Fun

Jeff Atwood on January 04, 2010

I noticed that the Stack Overflow question Strangest language feature has been closed and reopened several times now. The text of the question is brief:

What is in your opinion the most surprising, weird, strange or really “WTF” language feature you have encountered?

I agree this is not exactly an ideal question for Stack Overflow, per the FAQ:

Avoid asking questions that are subjective, argumentative, or require extended discussion. This is not a discussion board, this is a place for questions that can be answered! …

Interesting picture :-)

Integrator

13:44

@robjohn I knew that was going to happen!

@Sawarnik It was something about particular user's voting habit!

Sawarnik

@Integrator Which one can you tell? :D

Oh.

Integrator

@Sawarnik He/She has 5 up-votes

Sawarnik

@skullpatrol The photo is funny.

skullpatrol

yeppers

Sawarnik

^long word.

skullpatrol

13:50

could make a good avatar?

Sawarnik

Try.

skullpatrol

nah, not till my team wins

they're playing like girls

hence the pink

0-10

Sawarnik

Hmm.

Antonio Vargas

who upvotes this stuff?

UserX

4

Q: The Riemann Hypothesis not even wrong?

The ref Article updated. For the generalization of the RH we try to build two set which allow us to generate the zeros of the zeta functions and in the other hand to describe the perfect convergent series such that the LHS depends on $s$. The demonstration is too long $50$ pages, then we started...

elementary-number-theory cryptography riemann-zeta riemann-hypothesis

How did this get upvotes?

Famcy vocabulary&symbols mean upvotes?

Antonio Vargas

14:04

That's what I'm saying.

There's a deleted post by a user with a different name on the same topic, too.

Daniel Fischer

14:39

@AntonioVargas Thierno M. Sow creates a lot of sockpuppets, I think. Unfortunately, enough to have raised the score above the threshold for immediate 20k+ deletion again.

skullpatrol

14:52

how does the system allow that?

UserX

If my bounty question goes unanswered, will it be reasonable to ask MO in a similar manner to this question, mathoverflow.net/questions/186288/… ?

evinda

Hello!!! :-) Could you explain me the following sentence?

The p-adic numbers are complete with respect to the p-norm, ie every Cauchy sequence converges.

UserX

scribd.com/doc/233602815/Barnetts-Identity-Pdf1 hahaha read this

Antonio Vargas

15:10

@DanielFischer

Whoops, didn't mean to ping early.

Mike Miller

@DanielF I assume it's been flagged for moderators?

Antonio Vargas

Was just going to say, I don't think "invited article" is a real thing, either!

Daniel Fischer

@MikeMiller Don't know. I voted to delete (before it was re-upvoted to $-2$).

It's back at $-3$, any 20k-ers around?

skullpatrol

looks like there was an historic KO in Germany on Saturday night

Mike Miller

He's very... hostile, which is even worse than his 'questions' themselves, i think.

Guest

15:19

In general is every statement of the form $\forall x\forall y P(x,y)$ equivalent to the statement $\forall y\forall x P(x,y)$ ? That is, when using two universal quantifiers in a row, can we interchange their order without affecting the statement made?

Mike Miller

Yes, that's correct.

I'm rather sure that's an axiom in (standard) first order logic, but if not, it's at least provable from them.

niCk

Can anyone tell me the sequence which has the following generator ?
A(x) = 2 - x - 4x^2 + 8x^3 - 16x^4 + .....

Sorry to ask in such manner but I ve stuck for ages, I can't see the answer

UserX

@MikeMiller is GF(•) the same as Z/•Z?

Mike Miller

No. For every prime power $p^n$ there is a unique field of that order; for $n=1$ it's $\Bbb Z/p\Bbb Z$. But for, say, $p^2=9$, the latter thing is not a field (why?)

Jasper Loy

Why was my uninteresting sentence starred?

skullpatrol

15:35

ask on meta lol

Jasper Loy

I should ask on chat meta, lol.

skullpatrol

:D

Jasper Loy

Where is the chat meta?

skullpatrol

dunno

UserX

@MikeMiller it seems like a field to me. Finite fields only exist when the order is a prime power p^n. There is a $p$ for your case. I assume I'm dead wrong but why

Mike Miller

15:39

@UserX Well, what are the axioms of a field?

Jasper Loy

A field is green.

UserX

Ass comm dis id in

Does is fail one of them? I can't see it

The above are shortcuts I use for myself, I hope you understand them

skullpatrol

what about equality?

and closure

UserX

@skullpatrol addition identity axiom ensures equality

Oh multiplication too

Brb

Mike Miller

Check inverses again...

UserX

15:57

I must really suck at this because I'm not sure I'm checking the correct (candidate) field. Can you show me why it doesn't have an inverse?

Mike Miller

$3^2=0$. Good luck inverting that.

Pedro Tamaroff

@MikeMiller HARRO.

Transcript for

$Mathematics$ Mathematics