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##### Activity
ksayid
@ksayid
hi
Joe Corneli
@holtzermann17
Hi @ksayid thanks for checking in!
johnpaulguzman
@johnpaulguzman

hi, just wanted to ask: is there a logical-ordered listing of the subjects in planetmath? The ordering modes that I've found in the site was order by subject index or alphabetically.

i'm looking for a list that enumerates all the prerequisite concepts before introducing a new one like:
01-mappings
02, 03-surjective map & injective map
04-bijective map
05-set of natural numbers
06-countable set

Joe Corneli
@holtzermann17
Hi @johnpaulguzman thanks for the note! That kind of listing doesn't exist yet but it would be great to develop! What we can make sooner is a simple "term index" that would just list the terms like "surjective map" and so forth (but without the ordering). We could then put them in order based on the way the pages reference each other. I had played around a while ago with making an analysis of the contents according to "depth", just by counting the number of articles that refer to each article. I don't think I have the data from that experiment anymore, but it would be easy to reconstruct. Anyway, "coming soon" - I hope!
johnpaulguzman
@johnpaulguzman
Thanks for the clarification @holtzermann17 .
Christian N. Hofmann
@ch180
hi
i need a proof of catalan's identity
Christian N. Hofmann
@ch180
found it by myself. bye
Joe Corneli
@holtzermann17
@ch180 - first link by googling "planetmath catalan's identity". Good luck!
Joe Corneli
@holtzermann17
Looks like Native MathML plugin is working now $\square$.
LudicSavant
@LudicSavant
Hello
50789
@50789
how to do request?
ajb97
@ajb97

Hi there,
I am looking for a faster algorithm for counting the number of data points that are close to a particular point in k-dimensional hyperspace? The current method of calculating all the distances to data points is too slow for my application to handle.

(If this should be posted elsewhere then please let me know)

Ben
@bhpayne
@holtzermann17 Is the data for planetphysics available somewhere?
Tarit Goswami
@t-gos7
Hi, I am new here, can I know what does it mean by well defined ?
ouening
@ouening
transfer function
Ben
@bhpayne
eachirei
@eachirei
Hello
Can anyone help me with an issue about Scott-continuity?
eachirei
@eachirei
This is what I'm trying to solve; if you could give me any hints I'd be grateful
Ben
@bhpayne
@eachirei -- probably not the best forum for questions like this; see math.stackoverflow. Also, posting homework questions and providing no context of what you've attempted is unlikely to trigger someone to explain the answer.
How to look up an article in PlanetMath? I am looking for the article "http://planetmath.org/APointAndACompactSetInAHausdorffSpaceHaveDisjointOpenNeighborhoods"
The link doesn't work; it takes me to the home page for PlanetMath rather than the article
AndyYoung27
@AndyYoung27
Hi there , nice to meet you all
Joe Corneli
@holtzermann17
@genenaden indeed, that page seems to be missing for some reason. At some point we might be able to track it down.
abhishekpdeshmukh
@abhishekpdeshmukh
how does this chat room work?
khanrajaat
@khanrajaat
Anyone here?
nunesgrf
@nunesgrf
Hi
Can you guys help me with a proof?
Nabeegh Ahmed
@Nabeegh-Ahmed
@nunesgrf yes??
ScientificX
@ScientificX
Hey guys
zugzwang-alt
@zugzwang-alt
hello, do you guys have links or popular resources for engineering math?
hopefully open, and free :)
Shinkenjoe
@Shinkenjoe
good day party people
Shinkenjoe
@Shinkenjoe
I'm proofing my way through tao mostly sloppily and im considerung posting my so-called proofs here
id this hinders chat from pulsating tell me and ill stop,, wont be much anyways
*if
Shinkenjoe
@Shinkenjoe
(e) Let X and Y be finite sets. Then Cartesian product X ×Y is finite and #(X × Y) = #(X) × #(Y).
i'll try with induction over #Y
For #Y = 0 the cartesian product is the empty set and the proposition is trivially true.
So We know #(X1×Y1) = #X1 ⋅ #Y1
We try to prove #(X2×Y2) = #X2 ⋅ #Y2 for #Y2 = #Y1++
Let's choose an arbitrary element a2 from Y2 then #(Y2 \ {a2}) = #Y1
X2×Y2 = X2×(Y2{a2}) ∪ X2×{a2}
as both sets are disjoint #(X2×Y2) = #(X2×(Y2{a2})) + #(X2 × {a2})
and #(X2×(Y2{a2})) = #(X1×Y1{a2})
j: X2 → X2 ×{a2} = j(x) = (x, a2) for x in X2 is a bijection
so #(X2×{a2}) = #X2
and #(X2×Y2) = #(X2×(Y2{a2})) + #(X2×{a2}) = #(X1×Y1) + #X1 =
= #X1⋅#Y1 + #X1 = #X1⋅#Y1++ = #X2⋅#Y2
Shinkenjoe
@Shinkenjoe
hmm
i think illl rater spam my stuff in some forum
equilibriumwell
@equilibriumwell
Im in calc 2 anyone think they can give me a hand?
Victor Porton
@vporton
I discovered algebraic general topology and a generalization of limit for arbitrary functions: https://mathematics21.org - congratulate me
Victor Porton
@vporton
will submit to PlanetMath
vastcosmos
@vastcosmos
is the sum of two normally distributed random variable X and Y alwways norma
is the sum of two normal variable always normal??
Rana Zubair
@zubair444
hello
can someone please explain to me what is inverse CDF function. It will be really appreciated, i could not get any clear understanding of it.