## Search found 156 matches

- Mon Nov 18, 2013 6:24 pm UTC
- Forum: Mathematics
- Topic: Polynomial roots in a generic field
- Replies:
**2** - Views:
**1110**

### Re: Polynomial roots in a generic field

Followup, having found a formula in the book then searched online.....This seems to be Vieta's formulas, with the ring extensions. ( http://en.wikipedia.org/wiki/Vieta%27s_formulas So...the formula definitely holds, is the result back in the original integral domain/field though? Pretty sure...

- Mon Nov 18, 2013 6:08 pm UTC
- Forum: Mathematics
- Topic: Polynomial roots in a generic field
- Replies:
**2** - Views:
**1110**

### Polynomial roots in a generic field

So, in the course of a semi-unrelated problem, the following question came up. In the real numbers, polynomials factor into linear terms and irreducable quadratics, who's roots are complex congugates in the complex numbers. This means that if you take the complex numbers as algebraic complete field ...

- Mon Nov 18, 2013 6:20 am UTC
- Forum: Mathematics
- Topic: Cantor set problem from Pugh
- Replies:
**8** - Views:
**2518**

### Re: Cantor set problem from Pugh

Neat discussion, thanks for the thoughts! Of course, we're not even touching cantor sets in my class until next semester...silly professor doesn't use the textbook at all.

- Wed Nov 13, 2013 7:30 pm UTC
- Forum: Mathematics
- Topic: Cantor set problem from Pugh
- Replies:
**8** - Views:
**2518**

### Cantor set problem from Pugh

So I'm taking my first graduate level Analysis course, and the textbook has a three star problem in it: One that the author doesn't know the answer to. The book is Real Mathematical Analysis, by Charles Pugh. I thought I'd pose the problem here to see if anyone either knows the answer or would like ...

- Mon Oct 21, 2013 12:32 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1280: "Mystery News"
- Replies:
**42** - Views:
**11213**

### Re: 1280: "Mystery News"

Oh, and my quick fix to this problem is to mute my volume.

- Mon Oct 21, 2013 5:41 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1280: "Mystery News"
- Replies:
**42** - Views:
**11213**

### Re: 1280: "Mystery News"

BlitzGirl wrote:Or it might be a large computer-ish object known as your television. Try that.

What is this strange magic you speak of?

- Thu Oct 17, 2013 3:38 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1278: "Giraffes"
- Replies:
**67** - Views:
**21357**

### Re: 1278: "Giraffes"

My hobby: Enumerating Randall's hobbies.

(Not actually going to enumerate them, I'm lazy and have a linear algebra midterm I should be working on!)

(Not actually going to enumerate them, I'm lazy and have a linear algebra midterm I should be working on!)

- Thu Oct 17, 2013 2:14 am UTC
- Forum: Mathematics
- Topic: Order of magnitude of mathematical knowledge?
- Replies:
**3** - Views:
**2153**

### Order of magnitude of mathematical knowledge?

So, I was chatting with my fellow (first year) graduate students today and the question came up of "What percent of mathematical knowledge would one possess at the average new Ph.D of mathematics?" Obviously this is a question of order of magnitude, and it's somewhere pretty danged low. .0...

- Tue Oct 08, 2013 4:43 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1274: Open Letter
- Replies:
**162** - Views:
**39638**

### Re: 1274: Open Letter

Just ask Shadowfacts, duh!

- Fri Oct 04, 2013 3:26 pm UTC
- Forum: Mathematics
- Topic: Fields of characteristic 2?
- Replies:
**7** - Views:
**7468**

### Re: Fields of characteristic 2?

It does, quite a bit! Although I really need to bone down on my factor groups and ring ideals (We're doing factor groups now in Herstein's classic book, probably won't get to ring ideals until next semester at this pace)

- Fri Oct 04, 2013 4:08 am UTC
- Forum: Mathematics
- Topic: Fields of characteristic 2?
- Replies:
**7** - Views:
**7468**

### Fields of characteristic 2?

So, I'm a first semester grad student in mathematics, and in the course of my linear algebra class the professor messed up in the notes by not including the restriction that a bunch of the theorems for a vector space V over an arbitrary field F only held if the characteristic of the field is not 2. ...

- Thu Oct 03, 2013 5:25 am UTC
- Forum: Mathematics
- Topic: Linear functionals in an infinite dimension vector space
- Replies:
**11** - Views:
**3002**

### Re: Linear functionals in an infinite dimension vector space

An infinite-dimensional vector space doesn’t even necessarily have a basis…unless you assume the axiom of choice. Yeah, we've gone over that in class, that that's one of the many "Equivalents of the axiom of choices". Amusingly, when I turned in my homework I enumerated my bases for ease ...

- Wed Oct 02, 2013 12:42 am UTC
- Forum: School
- Topic: Plea from a first year Mathematics TA.
- Replies:
**8** - Views:
**5083**

### Plea from a first year Mathematics TA.

/rant on Dear prospective students preparing to enter a math class, Please read the prerequisites listed in the course catalog. These aren't there just to make you spend more money or more time. Contrary to popular opinion, mathematics actually does build upon itself. Among other things, this means ...

- Mon Sep 30, 2013 2:38 am UTC
- Forum: School
- Topic: PhD salary
- Replies:
**14** - Views:
**11372**

### Re: PhD salary

Florida state school here, math department, $20000+ tuition.

- Sun Sep 22, 2013 3:00 am UTC
- Forum: Mathematics
- Topic: Linear functionals in an infinite dimension vector space
- Replies:
**11** - Views:
**3002**

### Linear functionals in an infinite dimension vector space

So, I'm working on a problem in Halmos's Finite Dimensional Vector spaces book to show that there's an isomorphism between (V/M)' and M^0 (functionals on the quotient space and the annihilators space). As part of my proof of the one to one and onto correspondence, I used the fact that functionals ar...

- Fri Sep 20, 2013 8:43 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1267: "Mess"
- Replies:
**110** - Views:
**21074**

### Re: 1267: "Mess"

So, I'd just like to point out some basic things here in an attempt to restore sanity: Argument by repeated assertion usually means there's no actual argument/debate going on, just people talking AT each other. Arguing with someone you deem to be an idiot on the internet (Whether or not they actuall...

- Wed Sep 18, 2013 12:57 am UTC
- Forum: Mathematics
- Topic: examples of linear/multilnear functionals?
- Replies:
**3** - Views:
**1492**

### Re: examples of linear/multilnear functionals?

Got it now, thanks!

- Wed Sep 18, 2013 12:31 am UTC
- Forum: Mathematics
- Topic: examples of linear/multilnear functionals?
- Replies:
**3** - Views:
**1492**

### examples of linear/multilnear functionals?

So I'm taking my first graduate level class in Linear Algebra, and we've just covered introduced linear functionals/multilinear functionals/dual spaces. I feel like I understand the abstraction level, that we're learning it at.....the problem is, I'm not able to see concrete examples. So, going to s...

- Wed Sep 11, 2013 1:44 am UTC
- Forum: Mathematics
- Topic: Normal way to show Q(cube root of 2) is a subfield of R?
- Replies:
**7** - Views:
**4034**

### Re: Normal way to show Q(cube root of 2) is a subfield of R?

Thank you all for the replies, I'm (mostly) following where this goes....sadly, I kind of hazed over my polynomial ring ideals part of my undergrad abstract algebra class. Hopefully the grad level 1 will get me up to speed on this. (I was just kind of puzzled to find this problem in my _linear_ alge...

- Tue Sep 10, 2013 10:02 am UTC
- Forum: Mathematics
- Topic: Normal way to show Q(cube root of 2) is a subfield of R?
- Replies:
**7** - Views:
**4034**

### Normal way to show Q(cube root of 2) is a subfield of R?

So, I just had an assignment in my first graduate level class to show that the set consisting of a+b*(cube root of 2)+c*(cube root of 4), where a,b, and c are rational numbers is a subfield of R. The way I showed the only nontrivial part (Multiplicative inverses was) I mapped the multiplication of t...

- Tue Sep 10, 2013 9:53 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1262: "Unquote"
- Replies:
**100** - Views:
**19803**

### Re: 1262: "Unquote"

And yet, sadly, noone in my Spanish class in college had seen Rocky.

- Fri Sep 06, 2013 11:19 pm UTC
- Forum: Mathematics
- Topic: Partitioning a group by cosets-axiom of choice?
- Replies:
**2** - Views:
**1518**

### Partitioning a group by cosets-axiom of choice?

So, we were proving Lagrange's theorem in class today (about the order of a subgroup dividing the order of a group). In proving the step that the union of all left cosets of H partitions G, the professor wanted to limit it to finite groups for fear of invoking the axiom of choice. I am 99% confident...

- Fri Aug 30, 2013 10:23 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1258: First
- Replies:
**72** - Views:
**21760**

### Re: 1258: First

1258th!

(couldn't resist)

(couldn't resist)

- Fri Aug 30, 2013 7:03 pm UTC
- Forum: Mathematics
- Topic: Any usefulness of this metric?
- Replies:
**6** - Views:
**4328**

### Re: Any usefulness of this metric?

Nicias wrote:Sure. If you have a metric space where you want to preserve the topology but you want to make it bounded in diameter this could be useful since any two points always have d*(x,y)<1.

True, and neat. Thanks! (So glad to finally have made it into grad school. @whee!)

- Fri Aug 30, 2013 6:48 pm UTC
- Forum: Mathematics
- Topic: LaTeX advice?
- Replies:
**37** - Views:
**9589**

### Re: Latec advice?

Err, yes. Windows 8

- Fri Aug 30, 2013 6:48 pm UTC
- Forum: Mathematics
- Topic: Any usefulness of this metric?
- Replies:
**6** - Views:
**4328**

### Any usefulness of this metric?

So, I'm encountering metric spaces for the first time and my professor posed this homework question (Which I've solved btw, no help needed there): Let (E,d) be a metric space. Define a new d* function such that d*(x,y)=d(x,y)/(1+d(x,y)). Show that d* is also a metric on E. Other than an interesting ...

- Fri Aug 30, 2013 6:44 pm UTC
- Forum: Mathematics
- Topic: LaTeX advice?
- Replies:
**37** - Views:
**9589**

### LaTeX advice?

So, I've just started grad school, and I've never used any form of software for LaTeX...any advice on which I should use/where I can go to learn how to type up my math homework/papers?

- Mon Aug 12, 2013 6:24 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1250: "Old Accounts"
- Replies:
**54** - Views:
**50562**

### Re: 1250: "Old Accounts"

Post by TimeLurker

I'd be careful which online community you leave. I’ve heard of places where, if they suspect you might be leaving, they tie you up in their basement and force you too stay.

There are places you have to pay extra for that service!

- Fri Jun 28, 2013 7:04 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1231: "Habitable Zone"
- Replies:
**51** - Views:
**13701**

### Re: 1231: "Habitable Zone"

PiZZaMartijn wrote:Sounds like you need a edgeless safety cube

The earth actually has 4 24 hour days per day.....

- Fri Jun 28, 2013 6:50 pm UTC
- Forum: Mathematics
- Topic: Clever High School Math Problems
- Replies:
**31** - Views:
**13814**

### Re: Clever High School Math Problems

My favorite problem was posed to me after 5th grade as part of an entrance exam to an advanced math program Find a 10 digit number such that the first digit tells how many 0s there are in the number, the second digit tells how many 1s there are in the number, the third how many 2's, all the way up t...

- Tue May 28, 2013 5:33 am UTC
- Forum: Mathematics
- Topic: Origin of e as group identity?
- Replies:
**7** - Views:
**2543**

### Re: Origin of e as group identity?

Yeah, due to confusions and changing on requirements on me from my first to last years of finally getting my bachelor's degree, I ended up needing to get 2 semesters of a language in in spring/summer, and the only way I could guarantee that down here was to take Spanish. Le sigh. Hell, I'd have pref...

- Mon May 27, 2013 9:11 pm UTC
- Forum: Mathematics
- Topic: Origin of e as group identity?
- Replies:
**7** - Views:
**2543**

### Re: Origin of e as group identity?

Thanks...I knew there was a reason I wanted to take german, as opposed to the Spanish I found myself being made to take for scheduling reasons....

- Mon May 27, 2013 3:50 pm UTC
- Forum: Mathematics
- Topic: Origin of e as group identity?
- Replies:
**7** - Views:
**2543**

### Origin of e as group identity?

Out of idle curiosity for any history of math buffs, anyone know (or have a reasonable sounding theory) on the traditional use of the lower case e for the identity element of a group? (re)taking a modern algebra class now and it's been bugging me for no apparent reason.

- Sun Apr 21, 2013 5:17 pm UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1201: "Integration by parts"
- Replies:
**81** - Views:
**25617**

### Re: 1201: "Integration by parts"

So, I'm a bit confused at all the comments about it not being easy to teach people what, generally, they should use/identify for this technique. When I teach it, especially for beginning calculus problems, there are pretty much exactly two cases you'll use it. In both cases, its freaking obvious wha...

- Fri Mar 29, 2013 6:58 am UTC
- Forum: Individual XKCD Comic Threads
- Topic: 1192: "Humming"
- Replies:
**53** - Views:
**10980**

### Re: 1192: "Humming"

I just came here to say....you guys rock. We have the best geeks of all kinds gathered in one place, and this and Time and factoring graham's number+1 is what we do....

Cancer can wait!

Cancer can wait!

- Wed Mar 27, 2013 10:56 pm UTC
- Forum: Mathematics
- Topic: Speed limit for series convergance/divergence?
- Replies:
**4** - Views:
**1309**

### Re: Speed limit for series convergance/divergence?

No, Rudin has some good exercises that contribute to an argument that no such sequence exists http://math.stackexchange.com/questions/20378/which-series-converges-the-most-slowly Thanks for the link, followed it and the followups....not fully up to some of the theorems mentioned in the mathoverflow...

- Wed Mar 27, 2013 5:49 pm UTC
- Forum: Mathematics
- Topic: Speed limit for series convergance/divergence?
- Replies:
**4** - Views:
**1309**

### Speed limit for series convergance/divergence?

So, in the math lab we were talking about the idea of using the comparison tests as a "speed limit" for how fast a sequence needs to go to 0 in order for its series to converge. IE 1/x diverges, goes too slow. 1/(xlnx) goes a bit faster to 0, but is still too slow. 1/e^x is fast enough for...

- Tue Mar 26, 2013 2:48 am UTC
- Forum: School
- Topic: Awesome Teacher Quotes
- Replies:
**1764** - Views:
**394306**

### Re: Awesome Teacher Quotes

My Spanish teacher, on giving an explanation on the proper uses of one two different words for "to know"

"Conoces the Muffin Man?"

"Conoces the Muffin Man?"

- Fri Mar 22, 2013 7:22 pm UTC
- Forum: Mathematics
- Topic: (Semi homework) Recursive polynomial functions
- Replies:
**5** - Views:
**2091**

### (Semi homework) Recursive polynomial functions

So, I have a homework problem that we worked out how to solve, but it required one thing that's been asserted to be true, but I'm not sure why. The asserted fact is: If a function f(n) fits the form f(n+1)=f(n)+p(n), where p(n) is a known polynomial of degree k, then f(n) itself is a polynomial of d...

- Tue Mar 12, 2013 8:05 am UTC
- Forum: Mathematics
- Topic: Direction to study for Lambert W function?
- Replies:
**8** - Views:
**3859**

### Re: Direction to study for Lambert W function?

Ahh, I see. Thanks....the book I was reading from didn't make it clear that that was the origin of the W function and that it was the inverse of xe^x. So I was just staring at this odd piecewise defined function with power series/log series and was like "What is this?"