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Msc student at the university of Amsterdam. Main interests: algebraic and complex geometry, algebraic topology.

Also see: http://www.science.uva.nl/math/People/show_person.php?Person_id=Ronde+J.J.J.+de


21h
answered Can I use my powers for good?
Nov
23
comment Are simple extensions of isomorphic fields isomorphic?
Aii, I was too quick on that one, thanks @HenningMakholm!
Nov
18
answered Are simple extensions of isomorphic fields isomorphic?
Nov
1
comment Pullback of very ample sheaf again very ample? And other questions.
@claudi, if you comment on the answer instead of the question, the poster of the answer will be notified. I think he is in better shape to answer this than I am..
Oct
3
awarded  Popular Question
Sep
24
awarded  Autobiographer
Sep
21
comment example of non compact set for rationals
You should realize that being closed is a relative statement, in the sense that a space is always closed in some bigger space. And your set $K$ is closed in $\mathbb{Q}$, but not in $\mathbb{R}$. Now note that the Heine Borel theorem only works when the bigger space is $\mathbb{R}$ (or $\mathbb{R}^n$), see: en.wikipedia.org/wiki/Heine%E2%80%93Borel_theorem.
Sep
21
comment example of non compact set for rationals
Can you state what the definition of a compact set is again? That might help you already.
Sep
5
comment A $k+1$-sphere containing a $k$-sphere and a point.
Oops, too quick of a reading, apologies!
Sep
4
comment A $k+1$-sphere containing a $k$-sphere and a point.
Can't you do this using just one $R$ and no $R'$?
Aug
4
comment Reference request: Chern classes in algebraic geometry
Thanks for adding your answer!
Jul
24
comment $x^y < y^x$ for $y\ll x$?
Very good answer!
Jul
20
comment Formal construction of $\mathbb Q$: interpretation and equality of elements
One does not really say that $n$ and $(n,1)$ are strictly equal. However, there is a natural injective morphism from $\mathbb{Z}$ to $\mathbb{Q}$ as you just constructed it, where $n$ is sent to $(n,1)$. In this way we identify $\mathbb{Z}$ with this particular subset of $\mathbb{Q}$.
Jul
18
awarded  Yearling
Jul
13
awarded  Nice Question
Jul
2
awarded  Curious
Jul
2
awarded  Inquisitive
Jun
25
comment Checking derivation of y = a^x
A nitpick, use curly brackets like x^{-1} instead of x^-1 as you used... Otherwise very nice!
May
16
awarded  Nice Question
May
7
comment What is the integral of n-th root of tan x?
Ah, i was too quick, sorry for the hassle!