Math

cyclotomic_extension
Let x be a primitive 13th root of unity over Q. Let y be a primitive 7th root of unity over Q. What is the value of [Q(x,y):Q]? I know [Q:Q(x)]=12 and [Q:Q(y)]=6, but I don't think [Q(x,y):Q] = 72. What is the value of [Q(x,y):Q]? Is it the same with Gal(Q(x,y)/Q)? If not, what is value of Gal(Q(x,y)/Q)? Than... 27 Apr 2010 21:20

Webcams on Eyjafjallajökull
This site connects to three different webcams on the volcano: http://eldgos.mila.is/ At this moment one shows glowing hot ejecta and a plume of volcanic ash. Visibility changes from moment to moment so you might want to check the webcams daily. ... 27 Apr 2010 15:39

postscript Speed of Light derived from pure math #35; ATOM TOTALITY
Archimedes Plutonium wrote: (most snipped) Postscript: Chapter 18: "pi" and "e" and "i" explained; inverse fine structure constant, and proton to electron mass ratio, speed of light, all linked and explained. (snipped) So looking back at my posts on this topic, where I finally concluded: ... 26 Apr 2010 16:05

1 comment , 1 correction ( important !! )
i wrote : bobby wrote : Could somebody please tell me how to find the period of a taylor series ? What is the best way to compute that ? bobby ---- This is intresting. Since nobody wanted to reply or knows the answer , the master will help you ... 26 Apr 2010 14:56

Partial derivatives and an estimate
Hello dear community, please take a minute on this. Suppose we have a real valued function u(x1,...xn) such that, u(0)=0 du^k (0) / dxi^k = 0. k <= qi, i=1,..,n Can we conclude that u = o( x1^q1+1 ) + ... + o( xn^qn+1 ) ? Thanks ... 26 Apr 2010 14:56

Sum of independent random variables
Hi, Suppose we have Z = X + Y as non-negative real random variables, where X and Y are independent. Assume that we know the marginal pdfs for Z and Y, f_z(t) and f_y(t) respectively. I want to compute the marginal pdf for X, say f_x(t). Now I know f_z(t) = (f_x * f_y)(t), where * is the convolution operator, ... 26 Apr 2010 23:58

What is "modular"?
Whenever I look for a definition of modular (Forms, functions, curves) , I found very advanced definitions and terms. Is there a plain, intuitive, freshman level, definition of that concept? It's important for understand articles on the demonstration of Fermat Last Theorem, because all speak of Taniyama conjec... 28 Apr 2010 09:28

sci.math.moderated, informal version 2.1
[Crossposted with followups set to news.groups.proposals; change the followup if you wish your response to be seen elsewhere.] Top posted, in violation of my normal policy; the entire body of the original article is below. There has been informal discussion for the past week in news.groups.proposals about crea... 26 Apr 2010 09:09

Nowhere Continuous Functions
Hello, does there exist a nowhere continuous function f:R->R (where R denotes the set of real numbers), such that lim_{h->0} [f(x+h)-f(x-h)] = 0, for every x in R? Thank you very much for your attention. My Best Regards, Maury Barbato ... 27 Apr 2010 11:02

postscript Speed of Light derived from pure math #34; ATOM TOTALITY
Archimedes Plutonium wrote: (snipped) Postscript: Chapter 18: "pi" and "e" and "i" explained; inverse fine structure constant, and proton to electron mass ratio, speed of light, all linked and explained. Alright, I bounced around, back and forth several times now on deriving the speed of... 26 Apr 2010 01:33