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Apr
24
awarded  Nice Question
Apr
3
revised Non-Integrability of a Pfaffian - Geometric Interpretation?
Tried to improve tags in order to increase chance of an answer.
Apr
1
awarded  Good Question
Mar
25
revised Is a projective space a vector space? If not, what of a basis?
Formatting added.
Mar
24
awarded  Popular Question
Mar
19
revised No. of elements in the set $\{z\in \mathbb{C}: z^n=-1 \}$
edited tags
Mar
19
answered Find the matrix of a linear transformation
Mar
19
awarded  metric-spaces
Mar
18
awarded  Guru
Mar
18
revised Continuous function on a compact metric space is uniformly continuous
added 9 characters in body
Mar
18
comment Continuous function on a compact metric space is uniformly continuous
@Theo Oh, I see now what you mean! All this time I thought people where saying the $\delta$ were off by a factor of $2$. Duh. Of course one has to replace $\varepsilon$ by ${\varepsilon \over 2}$. The proof stays the same though.
Mar
18
revised Continuous function on a compact metric space is uniformly continuous
added 69 characters in body
Mar
18
comment Continuous function on a compact metric space is uniformly continuous
@Theo No: In the second paragraph the $\delta_i$ are actually equal to ${\delta_i \over 2}$ from the first paragraph. I believe this to be the factor of two that everybody is criticising in the comments. Right, that's the factor you are talking about?
Mar
11
awarded  Popular Question
Mar
11
revised If $d$ is a metric and $f$ a function when is $d \circ f $ a metric?
added 2 characters in body
Mar
7
comment A polynomial that is zero on an open set
This is not clear to me: Consider for example the polynomial $p(x,y) = xy$. Then this has degree one but $|\mathbb R|$ many roots. What am I missing?
Feb
29
comment Munkres' Topology Problem
@GiuseppeNegro Thanks for the link!
Feb
28
comment Munkres' Topology Problem
@DanielFischer I feel like a year ago I could do proofs like this with my eyes closed. Then I spent a year not doing any topology and now I can't even do the most basic thing. How depressing. Maybe my brain is broken.
Feb
28
comment Munkres' Topology Problem
@DanielFischer I deleted my shitey "answer".
Feb
28
comment Munkres' Topology Problem
@DanielFischer Hmmm. I am missing something. Why can the intersection not be closed while $A_\alpha$ aren't?