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Jul
20
awarded  Yearling
Jun
22
comment An easy example of a non-constructive proof without an obvious “fix”?
I guess what you mean is that the obvious classical proofs of this proposition can't be fixed. I think there may well be some entirely different constructive proof that hasn't been found yet.
Jun
1
comment Real world applications of category theory
@Niriel Transition went very well. You can read about the actual project here: theverge.com/2013/9/1/4680456/…
May
14
revised How many degrees of freedom would a rotation matrix in R5 have?
added 97 characters in body
May
14
comment How many degrees of freedom would a rotation matrix in R5 have?
@loupblanc Yes, quite right. I'll add a comment to the answer.
May
14
answered How many degrees of freedom would a rotation matrix in R5 have?
May
6
answered Book recommendation on infinitesimals
Apr
27
comment Why is $x^0 = 1$ except when $x = 0$?
If you're in the combinatorics business, zero is natural. If your business involves primes, zero is not. I'm not sure what people do when they have a foot in both camps.
Mar
16
comment Domain of log and its derivative
Did you mean to write $(0,\infty)$? The derivative clearly can't exist where the function being differentiated doesn't exist.
Mar
12
revised Examples where it is easier to prove more than less
deleted 7 characters in body
Mar
12
answered Examples where it is easier to prove more than less
Mar
12
comment How to explain brackets to young students
It sounds like this student has a very good understanding of brackets, something I've seen students struggle with. The problem here isn't with brackets, it's with addition.
Mar
12
comment Prove f(a)=f(b) if $\int_{-\infty}^{\infty}f(x)dx=1$
Very roughly: if f(a)>f(b) then shifting the region [a,b] left by δ would increase the integral by approximately δ(f(a)-f(b)) which would then allow you to shrink the length of the interval and still achieve the same integral.
Mar
3
awarded  Popular Question
Feb
11
awarded  Nice Answer
Dec
19
awarded  Caucus
Dec
15
comment Are the real numbers really uncountable?
@CarlMummert I'm not trying to say anything profound. Typically, in mathematics, when you want to pick a particular thing (in ZF, say) to talk about, you use a definition.
Dec
15
comment Proving $\int x \, \mathrm{d}y =xy- \int y \, \mathrm{d}x$
$\frac{dy}{dx}$ might look like a straightforward fraction, but it's not. You can't simply cancel $dx$'s without further justification.
Dec
3
comment Approximate solutions for quintic equation
See math.stackexchange.com/questions/309178/polynomial-root-finding
Nov
14
awarded  Necromancer