furrbear: (Geode Bear)
[personal profile] furrbear
∀ε>0 ∃δ>0 ∋ 0<|x-a|<δ⇒|ƒ(x)-L|<ε


Answer: Karl Weierstrass' Formal Definition of a Limit:

Let f be a real-valued function defined on an open interval of real numbers containing c (except possibly at c) and let L be a real number. Then

 \lim_{x \to c}f(x) = L

means that

for each real ε > 0 there exists a real δ > 0 such that for all x with 0 < |xc| < δ, we have |f(x) − L| < ε.

or, symbolically,

 \forall \varepsilon > 0 \ \ \exists \delta > 0 \ \ \forall x (0 < |x - c| < \delta \ \implies \ |f(x) - L| < \varepsilon).


[livejournal.com profile] fzks_cub was the first to respond with the words "definition of the limit"

Those who answered [livejournal.com profile] jrjarrett got the location from where I saw it correct, but missed the correct answer.

Date: 2009-04-15 11:35 pm (UTC)
From: [identity profile] fzks-cub.livejournal.com
i never actually learned the mathematician's name in calculus, we just called it the "epsilon/delta definition of a limit" or somethin casual like that, lol...

Date: 2009-04-15 11:41 pm (UTC)
From: [identity profile] geometrician.livejournal.com
Hmm... my response must've been lost in cyberspace. I replied that it was from [livejournal.com profile] jrjarrett's page, and that it was a definition of a limit. Oh, well.

Date: 2009-04-16 12:25 am (UTC)
From: [identity profile] furrbear.livejournal.com
My bad, I should have said "With one exception, those...". Yours was the ninth and last to get the def'n correct.

Date: 2009-04-16 12:38 am (UTC)
From: [identity profile] bearassed.livejournal.com
But wouldn't the final equation cancel itself out to a single variable?

Date: 2009-04-16 01:13 am (UTC)
From: [identity profile] jrjarrett.livejournal.com
I still want someone to produce the logical negation of that equation.

It was an extra credit assignment in Honors Calc I, and Dr. Cateforis said he would only say something if we got it right.

I think I thought about that for all 4 years of college.

Date: 2009-04-16 01:26 am (UTC)
From: [identity profile] westwind-mv.livejournal.com
Oh man, I missed it by a mere 14 minutes?!? Gotta be faster in the future.

Fun post; thanks!

Date: 2009-04-16 03:02 am (UTC)
From: [identity profile] gearjock.livejournal.com
Is that a hard or soft limit? :)

Date: 2009-04-19 10:06 am (UTC)
From: [identity profile] cuboz.livejournal.com
My brain just exploded.

!!!
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