4,488 reputation
1823
bio website
location
age
visits member for 2 years, 3 months
seen 5 hours ago

I'm a student of mathematics in Germany.


Apr
6
comment Vectorspace subspace proof
@user140831 Actually, I don’t think this answers the question entirely and I’m not sure if I thought of the whole solution when posting this. Maybe I was a bit confused. And maybe you’ve already done the rest, but if not, let me add: Any (non-zero) vector not contained in $W$ can be used to extend the base as the one to be left out later on. This proves $W^c ⊂ Y^c$.
Apr
6
comment Question about integration in $\mathbb{R}^n$
So we’re talking Riemann integrable here?
Apr
6
answered Vectorspace subspace proof
Apr
6
awarded  Pundit
Apr
6
comment Injection vs. Surjection: Mnemonic to remember which is which
@Sabyasachi “terminology” is Latin! : – D (and Ancient Greek, of course.)
Apr
6
comment Injection vs. Surjection: Mnemonic to remember which is which
@Sabyasachi I think it’s great terminology. See the answer by fgp.
Apr
6
comment Injection vs. Surjection: Mnemonic to remember which is which
Addendum: To be clear, “sur” is French from Latin “super”.
Apr
5
revised Proving that if $a,b > 1$, then $5^a - 3^b=16$ has only one solution with $a=2$ and $b=2$
added 7 characters in body
Apr
5
comment Proving that if $a,b > 1$, then $5^a - 3^b=16$ has only one solution with $a=2$ and $b=2$
@Sabyasachi I didn’t meant that comment to be final blow to the proof, but it’s unnecessary/misleading, so I’ll remove/replace it. (I was thinking it’ll be easier to think about it as factorization of positive integers, but I should have stressed the integer-part instead, yeah.)
Apr
5
comment Proving that if $a,b > 1$, then $5^a - 3^b=16$ has only one solution with $a=2$ and $b=2$
@YiyuanLee Beat me to it. : – /
Apr
5
answered Proving that if $a,b > 1$, then $5^a - 3^b=16$ has only one solution with $a=2$ and $b=2$
Apr
4
comment Probability of flipping 7 cards into the trashcan
What kinda deck?
Apr
4
comment What is Betti number of a group?
@Math-Nerd No, $ℤ$ and $ℤ × ℤ/2ℤ$ are not isomorphic.
Apr
4
comment What is Betti number of a group?
Well, there’s always group (co-)hohomology‌​.
Apr
4
comment What is Betti number of a group?
So the Betti number is the same as the rank? To me, this definition suggests that is the rank of the $k$-th homology group of the group.
Apr
4
comment Radon Measure and Radon Integrals
Looks like you can induce this from simple functions.
Apr
4
answered Fibonacci Sequence, Golden Ratio
Apr
4
comment Fibonacci Sequence, Golden Ratio
This is not a duplicate, but I once elaborated the computation here, have a look.
Apr
3
comment Are eigenspaces unique?
Well, $ℚ^2$ is spanned by $(1,0)$ and $(0,1)$, but you could also take $(1,1)$ and $(1,-1)$. Have you checked whether your spaces are equal at least?
Apr
3
comment How to show a directed set always has a “largest element” using induction
It does not. It might already convince you to say “The elements $a, b, c$ can all be the same.” But this is only half the truth: Generally, requiring that something holds for all elements (or pairs/triples of elements) doesn’t mean that there are such elements (let alone that there are such pairs/triples of different elements).