3,962 reputation
1619
bio website
location
age
visits member for 2 years
seen 8 hours ago

I'm a student of mathematics in Germany.


May
20
accepted Embeddings $A → B → A$, but $A \not\cong B$?
Apr
10
accepted How could I have found the closed form of $\sum_{k=1}^n \frac{k}{(k+1)!}$ in advance?
Mar
18
accepted Is every left maximal ideal the annihilator of a simple left module?
May
28
accepted Taylor expansion of $(1+x)^α$ to binomial series – why does the remainder term converge?
May
1
accepted Why is $\sum_{d \mid N} N/d ϕ(N/d) ϕ(d) = N^2 \prod_{p \mid N} (1 - 1/p^2)$?
Apr
28
accepted sine, cosine and the exponential by their differential equations
Jan
21
accepted Is there a sequence whose arithmetic means lie dense in $[-1..1]$?
Nov
24
accepted Does one restrict oneself when leaving out the inversion in the signature of groups?
Nov
17
accepted Is the inversion of an invertible map given by a formula again given by the inversion of that formula
Nov
15
accepted How to interpret material conditional and explain it to freshmen?
Nov
11
accepted troubles proving every subset of a finite set is finite with naive set theory
Nov
1
accepted is a non-falling rank of smooth maps an open condition?
Oct
20
accepted Complex projective line hausdorff as quotient space
Oct
10
accepted Visualizing Infinity discerning countable and uncountable
Oct
8
accepted Is there an associative (monoid) operation on $\mathbb{R}_{\geq 0}$ which is also a metric?
Oct
3
accepted Does every uncountable real set touch a rational number?
Oct
3
accepted Are inversion and multiplicaton open?