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Power set Cardinality

Name: Anonymous 2006-05-25 14:37

Did you guys know there isn't a surjection from a set to its Power set. ZING.

Name: Anonymous 2006-05-25 15:43

cool!

for your next assignment prove that if f is L^2 and its fourier transform F is L^1 then f equals integral of F(t)e^ixt dm(t) over R almost everywhere.

Name: Anonymous 2006-05-25 15:57

Pope Sixtus V limited the number of cardinals to 70 (six cardinal bishops, 50 cardinal priests, 14 cardinal deacons). In 1975, Pope Paul VI created the age limit on electors and raised the limit to 120 cardinal electors. But the numerical limitations have been frequently disregarded in order to make the College of Cardinals a more representative body.

Name: Anonymous 2006-05-25 18:52

>>2

gb2/measure theory/

Name: Anonymous 2006-05-26 3:03

This topic needs more tits.

Name: Anonymous 2006-05-26 12:19


>>3
lol

Name: Anonymous 2006-05-26 17:57

>>1
it's a basic theorem of abstract set theory...
"2^x>x whenever x is a cardinal number"...
if you find a surjection from a set to it's power set, that would imply that the cardinal of the set (say x) is greater then or equal to the cardinal or it's power set (which is 2^x).... that contradicts the theorem and hence leads to the failiure of set theory...

Name: Anonymous 2006-05-26 18:05

>>7
yes i know. i am just informing other people.

Name: Anonymous 2006-05-26 18:17

>>7

prove |2^x|>|x| where 2^x is the power set of x.

Name: Anonymous 2006-05-26 18:40

x = 1

 LHS  2^1 = 2
 RHS  1 = 1
 2 > 1

assume true for x = k > 1
x = x + 1

 LHS  2^(x+1) = 2(2^x)
 RHS  x + 1
 2^x > x
 2(2^x) > 2x
 2^(x+1) > x + x
 2^(x+1) > x + 1  since x > 1

INDUCED

Name: Anonymous 2006-05-26 18:52

>>10

That proof only works for the case of finite sets and their power sets.

What if the set if infinite. Say the natural numbers N. Show |2^N|>|N|

Name: Anonymous 2006-05-26 19:00

well then they're equal, silly!

Name: Anonymous 2006-05-26 19:13

>>12

i hope you are joking.>>12

Name: Nereid 2006-05-28 3:09

You can make a one-to-one mapping between N and P(N). (P means power set btw)

Name: Anonymous 2006-05-28 11:40

>>14

No you can't you fucking noob.

Name: Anonymous 2006-05-28 14:31 (sage)

>>15
Oh yeah!? PROVE YOUR AXIOMS, ASSHAT!!

Name: Anonymous 2006-05-28 20:23

>>16

What will you give me if I did? Here is a hint for you. Suppose there is a surjection f from a set X to its power set P(X), now look at the set
S={x in X such that x is not in f(x)}

good luck retard.

Name: Anonymous 2006-05-29 9:47

>>16
"Oh yeah!? PROVE YOUR AXIOMS, ASSHAT!!"

You can't prove an axiom you tard, that's WHY they're called axioms. And this is not an axiom, it is most certainly proveable.

Learn your fucking maths.

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