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My Alt
ILU2 :h:

caps


:h:

caps (lolwut)
refref
Did you ever finish that book? (the green one by george E.Andrews)

No, but to be honest I still don't like the proof on the page 7 but understand it. One day I will finish the book.

My Alt
I dunno I try to understand combinatorics by picturing it.

"Choosing" is very easy to picture

I find if there is extra information like if you choose this you have to choose this, then yeah I can't seem to follow the reasoning.

Even then choosing doesn't give out any information and is linked to the bionmial coefficients which the proofs I don't fully understand.
Reply 2122
Simplicity
No, but to be honest I still don't like the proof on the page 7 but understand it. One day I will finish the book.


I find if there is extra information like if you choose this you have to choose this, then yeah I can't seem to follow the reasoning.

Even then choosing doesn't give out any information and is linked to the bionmial coefficients which the proofs I don't fully understand.


It's a bit of a crazy proof. I'm only doing 3 subjects at A2 at the moment (essentially 2, FM + physics) so I might as well do some reading...

analysis or number theory? which to start first?
Simplicity
Nah, that is inefficient. The best bet is learning the theory and if you can't do that picturing or better skecthing it. That way you don't need to do the calculations.

You mean the integration. Which, one but looking at it in one minute.
a, i, ln(coshx)+c
ii. let u=sinx-cosx, then the result drops out.
iii. This is hard if you don't know a trick. But, you need the top to look like the bottom so, just add 3 and takeaway 3(obviously have to have same denominator).
iv. That actually looks tricky, I would say break up. I would break it up into complex numbers, but you probably haven't seen that technique. You can then just integrate around a real part or a complex part.

b. i. let u=lnx and dv=1 dx.
ii. let u=4-x^2
(in both case check for sigularities. )


Exactly what I was after <3

For iii though, how does doing that trick help?
can you cancel the top bit then and have 3/denominator and intagrate that.

wouldnt iv be partial fractions?
and both b have singulariates, what to do then?
refref
It's a bit of a crazy proof. I'm only doing 3 subjects at A2 at the moment (essentially 2, FM + physics) so I might as well do some reading...

analysis or number theory? which to start first?

I have done so many proofs that the proof doesn't look crazy anymore. Hmm, to be fair if you can yourself a copy of Halmos Naive Set Theory or maybe even better Rotman A first course in Abstract Algebra you should read it.

I would say naive set theory or maybe algebra like group theory.

P.S. If you download a djvu player I can show you how to get books for free. :p:
ste0731
Exactly what I was after <3

For iii though, how does doing that trick help?
can you cancel the top bit then and have 3/denominator and intagrate that.

wouldnt iv be partial fractions?
and both b have singulariates, what to do then?

Yes, the bit cancels down to 1, then you have to integrate the
-3/denominator.

So you get x -3 \integrate 1/blah.

Take the limit and see what happens?

Note, if their is a singularity between the limits you would have to break them down.

For iv, yes but the problem with that is that x^2+1 is complex, so you need to integrate around a real or imaginary part. I will post a thread in maths section about that now.
Reply 2126
Simplicity
No, but to be honest I still don't like the proof on the page 7 but understand it. One day I will finish the book.


I find if there is extra information like if you choose this you have to choose this, then yeah I can't seem to follow the reasoning.

Even then choosing doesn't give out any information and is linked to the bionmial coefficients which the proofs I don't fully understand.


Hmmm, I couldn't get the proofs without some sort of "picture" though. Like

(nr)+(nr+1)=(n+1r+1)\binom{n}{r}+\binom{n}{r+1}=\binom{n+1}{r+1}

Take a group of n people + 1, choose r+1 from it. You can take r+1 from a group of n and not choose the +1 or you can take r from the group of n and choose the +1. Or ginger as our lecturer called him iirc. Very easy argument to understand.

Elsy the caps was so that ILU would be in capitals.
.matt
+1 for the hating of Number Theory. I've never even attempted to study it, but I still hate it...not entirely sure why. Same goes with Combinatorics. :hmmm:

What's wrong with Combinatorics? It's pretty and I completely disagree with those people saying that you can't visualize it... I can't visualize algebra but combinatorics? Pictures are usually one of my first steps to trying to solve a combinatorics problem...

By the end of the year I will have done more modules in combinatorics than in algebra.
My Alt
Hmmm, I couldn't get the proofs without some sort of "picture" though. Like

(nr)+(nr+1)=(n+1r+1)\binom{n}{r}+\binom{n}{r+1}=\binom{n+1}{r+1}

Take a group of n people + 1, choose r+1 from it. You can take r+1 from a group of n and not choose the +1 or you can take r from the group of n and choose the +1. Or ginger as our lecturer called him iirc. Very easy argument to understand.

Elsy the caps was so that ILU would be in capitals.

What the hell, that isn't a picture. Thats just wordss....

But, like in grad in vector calculus I have one picture to understand it. No messing around with this and that and choose this from this e.t.c.

IrrationalNumber
What's wrong with Combinatorics? It's pretty and I completely disagree with those people saying that you can't visualize it... I can't visualize algebra but combinatorics? Pictures are usually one of my first steps to trying to solve a combinatorics problem...

By the end of the year I will have done more modules in combinatorics than in algebra.

I consider combinatorics to be a mathematics of the trivial i.e. counting. But, yeah you wont see anyone in bourbaki group doing that. I would think algebra is the most trivial to visualize.

Save your soul.

P.S. Algebra in particular vector calculus and lie algebra can actually done using a visual notation, sadly I have to wait intill next year intill I study tensors so don't really want to learn the notation now and lie algebra in about three years.
Reply 2129
Simplicity
What the hell, that isn't a picture. Thats just wordss....


Not in my head its not :smile:
My Alt
Not in my head its not :smile:

Okay, its a movie not a picture.

Anyway, reasoning from pictures that just stupid. Hence, why combinatorics isn't a real branch of mathematics. Because, real mathematics i.e. the bourbaki ways say you shouldn't reason from pictures hence having no pictures in their books.
Reply 2131
Simplicity
Okay, its a movie not a picture.

Anyway, reasoning from pictures that just stupid. Hence, why combinatorics isn't a real branch of mathematics. Because, real mathematics i.e. the bourbaki ways say you shouldn't reason from pictures hence having no pictures in their books.


Real mathematics isn't what Bourbaki says.
SimonM
Real mathematics isn't what Bourbaki says.

Yeah, it what Grothendieck says it is. Anyway, he would never draw a picture or reason from pictures.
SimonM
Real mathematics isn't what Bourbaki says.

Yeah, it what Grothendieck says it is. Anyway, he would never draw a picture or reason from pictures.
Reply 2134
Simplicity
Yeah, it what Grothendieck says it is. Anyway, he would never draw a picture or reason from pictures.


No it isn't
Reply 2135
IrrationalNumber
What's wrong with Combinatorics? It's pretty and I completely disagree with those people saying that you can't visualize it... I can't visualize algebra but combinatorics? Pictures are usually one of my first steps to trying to solve a combinatorics problem...

By the end of the year I will have done more modules in combinatorics than in algebra.


I'm not entirely sure actually, I just seem to have an irrational aversion to discrete maths. It probably didn't help that I did go to the first Combinatorics lecture, but was sat on the floor in some hot sweaty lecture theatre looking at bloody powerpoint slides...

Looking at the lecture notes (the enumerative combinatorics ones on Mathstuff) the course does actually look pretty fun :o: I guess I can just hoard the notes from the courses I've not taken for a rainy day!
SimonM
No it isn't

Yes it is.

Adding more, abstraction should be the goal in mathematics. But, combinatorics is not abstract, hence stupid.
Reply 2137
Simplicity
Yes it is.

Adding more, abstraction should be the goal in mathematics. But, combinatorics is not abstract, hence stupid.


I'm not going to bother arguing this. You're wrong
Reply 2138
amen

maths can be whatever I want it to be :h:
My Alt
amen

maths can be whatever I want it to be :h:

Well, no.

P.S. Certainly, crank maths comes to mind.

In other news, hope I will never appear in this site http://www.crank.net/maths.html

Apparently pi is 3.125. http://www.youtube.com/watch?v=7T0d7o8X2-E&feature=player_embedded#

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