# Maths Uni ChatWatch

#1301
(Original post by SimonM)
What do you mean by "count"?
A bijection between a set and the integers.
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9 years ago
#1302
(Original post by Simplicity)
A bijection between a set A and the integers.
I don't like that definition of count to be honest, and I'm certain that around does know that
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9 years ago
#1303
Yknow the cool thing is I'm doing a maths degree but I'm essentially here to do Physics.

edit; yup did countability today so we were all up to scratch. Want some of our countability example sheet questions Simplicity?
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#1304
(Original post by SimonM)
I don't like that definition of count to be honest, and I'm certain that around does know that
You got a better definition? I actually find its a really elegant definition and all of it is based on a really good proof by induction. Which, I would post but yeah Totally Tom would get annoyed.

(Original post by My Alt)
Yknow the cool thing is I'm doing a maths degree but I'm essentially here to do Physics.

edit; yup did countability today so we were all up to scratch. Want some of our countability example sheet questions Simplicity?
That isn't cool. Physics isn't cool. Maths is cool.

Countability isn't interesting, did you do uncountability yet i.e. Cantors diagonal argument.

P.S. Nice sig. Trolling a pedo using Pokemon.
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9 years ago
#1305
(Original post by Simplicity)
That isn't cool. Physics isn't cool. Maths is cool.

Countability isn't interesting, did you do uncountability yet i.e. Cantors diagonal argument.

P.S. Nice sig. Trolling a pedo using Pokemon.
i - Physics is cool, you just don't know it yet
ii - Countability is far more interesting than uncountability, considering we really know **** all about uncountable sets. Have seen cantors diagonal argument, have also seen the non-existance of a bijection from a set to it's power set, both very cool. Just as an aside looks cool
ii - Yeah thanks, always thought it was a cool thing to do, never tried it myself, though.
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9 years ago
#1306
(Original post by Simplicity)
You got a better definition? I actually find its a really elegant definition and all of it is based on a really good proof by induction. Which, I would post but yeah Totally Tom would get annoyed.
When I think of counting I think of how much of stuff I've got (in some vaguely discrete sense (as opposed to measure)). In which case, I think ordinals a more "natural" thing.

Also, I think when people talk about "countability" as a subject, they often lump together the idea of "deciding" if things are countable or not
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#1307
(Original post by My Alt)
i - Physics is cool, you just don't know it yet
ii - Countability is far more interesting than uncountability, considering we really know **** all about uncountable sets. Have seen cantors diagonal argument, have also seen the non-existance of a bijection from a set to it's power set, both very cool. Just as an aside looks cool
ii - Yeah thanks, always thought it was a cool thing to do, never tried it myself, though.
QM is kind of cool. I might do that next year.

Actually, I think that is wrong, actually uncountable sets are more general than countable sets. Well, its not really a diagonal argument for powersets, more like defining a subset that can't be hit and showing that it must exist.

(Original post by SimonM)
When I think of counting I think of how much of stuff I've got (in some vaguely discrete sense (as opposed to measure)). In which case, I think ordinals a more "natural" thing.

Also, I think when people talk about "countability" as a subject, they often lump together the idea of "deciding" if things are countable or not
But, that isn't counting, thats cardinality.

Well, I don't know what you are trying to say. Well, if something is describable in finite terms and you form a set from all the describable stuff then it would be countable. Its pretty trivial stuff.

Well, finding whats equipotent and maybe stuff like CH is pretty annoying.
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9 years ago
#1308
(Original post by Simplicity)
QM is kind of cool. I might do that next year.

Actually, I think that is wrong, actually uncountable sets are more general than countable sets. Well, its not really a diagonal argument for powersets, more like defining a subset that can't be hit and showing that it must exist.
I never said the diagonal argument and the power set argument were the same thing
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9 years ago
#1309
Got to miss yet another lecture today to go doctors Tonsilitis sucks!
And i'm in pain and getting no sleep due to not breathing properly. Might get a special circumstances form so I don't lose marks for not handing in my calc work. Not the best of weeks =(
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9 years ago
#1310
(Original post by Simplicity)
But, that isn't counting, thats cardinality.
That would be cardinals rather than ordinals
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9 years ago
#1311
(Original post by Simplicity)
I will watch that someday, but I can't find it online.

there's a website called animefreak.com and it has the full version of the first series and the Brotherhood version as it comes out i have to wait a whole week for the each episode to come out
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#1312
(Original post by SimonM)
That would be cardinals rather than ordinals
Sounds interesting. When I have the time I might actually read the book I got on set theory as it has a chapter on ordinal arithmetic.
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9 years ago
#1313
(Original post by Simplicity)
You don't do infinite sets. All you get is horrible number theory.
I get none of this, Durham hasn't even done set theory, which I reckon would upset you if you were here. Just Belgian-style Calculus, Analysis, Linear Algebra and Problems.
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9 years ago
#1314
(Original post by assmaster)
I get none of this, Durham hasn't even done set theory, which I reckon would upset you if you were here. Just Belgian-style Calculus, Analysis, Linear Algebra and Problems.
Next term in probability you will...
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9 years ago
#1315
(Original post by Simplicity)
QM is kind of cool. I might do that next year.
Yes, yes, yes, QM is made of awesomesauce. Hopefully I will be specialising in that sort of thing .

(Original post by My Alt)
Yknow the cool thing is I'm doing a maths degree but I'm essentially here to do Physics.
Win . Physics taught from a mathematical perspective is awesome.
9 years ago
#1316
(Original post by Simba)
Win . Physics taught from a mathematical perspective is awesome.
I couldn't agree more. I can laugh at other Physicists for being rubbish at maths, tell pure mathematicians that they are boring and be able to back that opinion up because I've done (will have done) the courses!

Who wrote Welcome Back Grae on the board today? I want to give them a rather large hug.
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9 years ago
#1317
(Original post by My Alt)
I couldn't agree more. I can laugh at other Physicists for being rubbish at maths, tell pure mathematicians that they are boring and be able to back that opinion up because I've done (will have done) the courses!

Who wrote Welcome Back Grae on the board today? I want to give them a rather large hug.
You can't back up your opinion because you've done the courses. You can merely say "I think it's boring" which tells you nothing about the people. A man should not be judged by the courses he takes at university. (Except Media Studies)

I believe that was Glutamic Acid, writing "WELCOME BACK GREAL"
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9 years ago
#1318
Yes, it was a slight at pure mathematicians. Glad you bit

That was Glut, cool

edit: yes the "exclaimation mark" was particularly badly done
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9 years ago
#1319
Me and my friends conversation went like this
him: "who's grael?"
me: "Thats not an l, it's an exclamation mark"
him: "Oh right... who's grae?"
*facepalm*
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#1320
(Original post by assmaster)
I get none of this, Durham hasn't even done set theory, which I reckon would upset you if you were here. Just Belgian-style Calculus, Analysis, Linear Algebra and Problems.
No wonder Durham has such a high rate of people getting firsts.

(Original post by Hopping Mad Kangaroo)
Next term in probability you will...
That isn't set theory. Yes set theory notation is used and all that stuff, but I doubt you will do stuff like cantors diagnonal argument in probability. Well, unless Durham has a totally different probability course to the one I'm currently suffering from. I can't wait intill next year and few months as then I wouldn't have to do a piece of stats in my life, I hope.

(Original post by Simba)
Yes, yes, yes, QM is made of awesomesauce. Hopefully I will be specialising in that sort of thing.
Well, QM is only interesting to me as I heard that it has some deep connections with number theory particulary the distribution of primes.

(Original post by My Alt)
I couldn't agree more. I can laugh at other Physicists for being rubbish at maths, tell pure mathematicians that they are boring and be able to back that opinion up because I've done (will have done) the courses!

(Original post by SimonM)
You can't back up your opinion because you've done the courses. You can merely say "I think it's boring" which tells you nothing about the people. A man should not be judged by the courses he takes at university. (Except Media Studies)
I don't know about that. If the person in question hasen't taken Maths or maybe Physics then you can conclude that the person in question is an idiot.

(Original post by My Alt)
Yes, it was a slight at pure mathematicians. Glad you bit
Looks like someone can't cut it at real maths.
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