## Search found 22 matches

- Sat Dec 24, 2011 4:00 pm UTC
- Forum: Mathematics
- Topic: Multiple Choice Problem
- Replies:
**9** - Views:
**1897**

### Re: Multiple Choice Problem

Wow whose bumping all those old threads !!!

- Fri Dec 23, 2011 5:27 pm UTC
- Forum: Mathematics
- Topic: Math Books
- Replies:
**378** - Views:
**249145**

### Re: Math Books

Hi everybody. I was wondering if someone had a good suggestion for a book on advanced number theory . Also I'm looking for a good book on intuitionism. I've tried Intuitionism , An Introduction by Heyting but I hate the Galileo " Discourses and Mathematical Demonstrations Relating to Two New Sc...

- Wed Dec 21, 2011 6:10 pm UTC
- Forum: Mathematics
- Topic: Odd factors of 2^n-1?
- Replies:
**5** - Views:
**2090**

### Re: Odd factors of 2^n-1?

It's pretty hard without modular arithmetic ... but once you know Euler's theorem and Euler's totient function the proof becomes pretty trivial ( 2 is always coprime to odd numbers so if n is an odd number : 2^{\phi(n)} \equiv 1 \ (mod \ n) which means that 2^{\phi(n)} - 1 is...

- Thu Dec 08, 2011 8:26 pm UTC
- Forum: Mathematics
- Topic: Convergence Tests For Series
- Replies:
**29** - Views:
**5878**

### Convergence Tests For Series

Hi everybody. I was just wondering if there is a theorem or logical reasoning why convergence tests for series will always be inconclusive for certain series ... Thanks for your help.

- Thu Dec 01, 2011 4:46 pm UTC
- Forum: Mathematics
- Topic: Requesting Inequalities and Tips to Solving Them
- Replies:
**9** - Views:
**2192**

### Re: Requesting Inequalities and Tips to Solving Them

If you want some really advanced notions of inequalities, I advise you to read "Handbook of Means and Their Inequalities" by Bullen. It's a bit bulky but very informative ...

- Thu Dec 01, 2011 3:17 pm UTC
- Forum: Mathematics
- Topic: can you crack it?
- Replies:
**13** - Views:
**8135**

### Re: can you crack it?

I thought it was an Ascii art or some phonetic lingo rather than a real cryptographic problem ... I tried ascii arting it and got something like an S or a 5 or an inverted Z but the other half was bullsh*t though ... so maybe it's just a crypto then

- Fri Nov 18, 2011 3:23 pm UTC
- Forum: Science
- Topic: Well, this could change things (neutrinos)
- Replies:
**289** - Views:
**40340**

### Re: Well, this could change things (neutrinos)

Hmmm I have a noob question: How do they measure the time of departure and time of arrival of these neutrinos ???

- Sat Nov 12, 2011 1:27 pm UTC
- Forum: Logic Puzzles
- Topic: The surprise exam paradox
- Replies:
**217** - Views:
**63101**

### Re: The surprise exam paradox

Still don't understand why this isn't classed simply as an inconsistent theory.

- Fri Sep 23, 2011 8:05 am UTC
- Forum: Science
- Topic: Well, this could change things (neutrinos)
- Replies:
**289** - Views:
**40340**

### Re: Well, this could change things

Thought it was from a school lab, but if it's from the CERN then there's a high chance it could be true. But I really hope that they made a mistake cos it could bring down 100 years of physics ....

- Sat Sep 17, 2011 7:11 pm UTC
- Forum: Mathematics
- Topic: Proof By Induction
- Replies:
**13** - Views:
**1880**

### Re: Proof By Induction

Thanks everybody for your posts and helping me clear this doubt. But I still think that I'll avoid using induction because I could be sacrificing real mathematical understanding for convenience. :D By the way the book was Discrete Mathematics by Rosen and the quote :"It is extremely important t...

- Thu Sep 15, 2011 6:27 pm UTC
- Forum: Mathematics
- Topic: Proof By Induction
- Replies:
**13** - Views:
**1880**

### Proof By Induction

Hi everybody. I've been reading a few books about mathematical reasoning and I came across an interesting statement in one of the books but I can't remember which one, which said something like "induction can only be used to prove a result obtained some other way but can't be used to discover n...

- Mon May 30, 2011 5:00 pm UTC
- Forum: Mathematics
- Topic: alternative mathematics
- Replies:
**128** - Views:
**13394**

### Re: alternative mathematics

kumarevo wrote:The existing angles of 180 degrees, if you specify items may be quadrilateral, pentagon...

task. prove ,to be a real number , result of division of two integers (a fraction)

With the commas it's clearer.

This is becoming more linguist and hieroglyphical than a mathematical

- Wed May 25, 2011 2:01 pm UTC
- Forum: Mathematics
- Topic: Cutting a polygon into triangles (Polygon triangulation)
- Replies:
**2** - Views:
**1817**

### Re: Cutting a polygon into triangles (Polygon triangulation

Is it what you meant Tirian? 2.png Let N n be the number of ways of triangularising a n-polygon. If I fix a side and draw a triangle to any vertex ( excluding the fixed side) , I always get two polygons on the left and on the right of my triangle whose sum of sides= n+1. Because the number of ways o...

- Wed May 25, 2011 10:12 am UTC
- Forum: Mathematics
- Topic: Cutting a polygon into triangles (Polygon triangulation)
- Replies:
**2** - Views:
**1817**

### Cutting a polygon into triangles (Polygon triangulation)

I was reading about Catalan numbers in a book and it said that the number of ways of cutting a n side convex polygon into triangles is the n-2 th Catalan number e.g for a pentagon there's 5 ways and for a hexagon there's 14 ways. http://upload.wikimedia.org/wikipedia/commons/3/36/Catalan_number_poly...

- Sun May 22, 2011 12:33 pm UTC
- Forum: Mathematics
- Topic: alternative mathematics
- Replies:
**128** - Views:
**13394**

### Re: alternative mathematics

Natural axiom: Natural along. Point is the beginning (end) longer natural. Natural along with 2 points. Natural along the base length. Natural longer connecting points. There is always the first point (A). MS.A-Natural along . Point . What does Natural along mean? Give us a clear and simple example...

- Thu May 19, 2011 8:50 am UTC
- Forum: Mathematics
- Topic: Solving PDE's
- Replies:
**9** - Views:
**1500**

### Re: Solving PDE's

Ok last question. If y = x− ct and z = x+ct and u(x,t)=v(y(x,t),z(x,t)) then using the Chain rule is the following eqn correct ?: \frac{\delta u}{\delta t}= \frac{\delta v}{\delta y}\frac{\delta y}{\delta t}+ \frac{\delta v}{\delta z}\frac{\delta z}{\delta t} And also I'm not too sure how to apply ...

- Wed May 18, 2011 5:31 pm UTC
- Forum: Mathematics
- Topic: Solving PDE's
- Replies:
**9** - Views:
**1500**

### Re: Solving PDE's

Ok last question. If y = x− ct and z = x+ct and u(x,t)=v(y(x,t),z(x,t)) then using the Chain rule is the following eqn correct ?: \frac{\partial u}{\partial t}= \frac{\partial v}{\partial y}\frac{\partial y}{\partial t}+ \frac{\partial v}{\partial z}\frac{\partial z}{\partial t} And also I'm not too...

- Tue May 17, 2011 8:23 pm UTC
- Forum: Mathematics
- Topic: Solving PDE's
- Replies:
**9** - Views:
**1500**

### Solving PDE's

Hi everybody. Just wondering if someone can help me out on some simple PDE's. Btw I'm just a math student and we're supposed to know how to solve some easy PDE's this semester but all the tutorials I've come across on the internet contain a lot of Physics and Engineering jargon. So I have to solve t...

- Mon May 02, 2011 12:24 pm UTC
- Forum: Mathematics
- Topic: Math Olympiad Problems
- Replies:
**8** - Views:
**1904**

### Re: Math Olympiad Problems

I did 3 by a long and rigourous method , by breaking up the digits into sequences For 7: 7\times10^{2n+2} , n\geq0 , where n represents the nth term For 1's: (\sum_{i=0}^{n}10^{n+1+i}) - 10^{n+1} = 10^{n+1}(\frac{10^{n+1}-10}{9}) For 2: 2\times10^{n+1} For 8's: (8\sum_{i=0}^{n}10...

- Fri Apr 22, 2011 10:32 am UTC
- Forum: Mathematics
- Topic: Tarski's World
- Replies:
**3** - Views:
**1622**

### Re: Tarski's World

Thanks a lot. Now it seems to make sense !!!

- Tue Apr 19, 2011 8:19 am UTC
- Forum: Mathematics
- Topic: Tarski's World
- Replies:
**3** - Views:
**1622**

### Tarski's World

Hi everybody. I'll be doing FOL next year so I'm reading a book on Tarski's World but I don't have the software. So if someone could please give me a brief description of what "Tarski's World" is all about and how it works , I'll be grateful

- Mon Apr 04, 2011 12:43 pm UTC
- Forum: Logic Puzzles
- Topic: The surprise exam paradox
- Replies:
**217** - Views:
**63101**

### Re: The surprise exam paradox

I think that the subtlety here is predicting that an exam will take place and predicting that an exam won't take place. Let's assume on Thursday evening the students predict that the exam will take place on Friday and stop they their reasoning there. On Friday morning they tell their professor "...