How to show the canonical embedding $c_0\rightarrow c_0^{**}$ is not surjective?
132713
The space $c_0$ of sequences that converge to 0 is not reflexive
3296
Proof That $\mathbb{R} \setminus \mathbb{Q}$ Is Not an $F_{\sigma}$ Set
35569
Prove that $[0,1]$ isn't homeomorphic to $\mathbb{R}$
14994
Showing a function $f$ cannot be surjective
148616
When is a ring homomorphism $A \to A$ surjective but not injective.
15418
Why is the space of surjective operators open?
70712
How to prove that $k[x, xy, xy^2, \dotsc]$ is not noetherian?
145462
On the canonical isomorphism between $V$ and $V^{**}$
126593
How to find out whether a transformation is a canonical transformation?
137761
Why are the fundamental and anti-fundamental representation in $\text{SL}(2,\mathbb{C})$ not equivalent?
155604
Show that $k[x,y]/(xy-1)$ is not isomorphic to a polynomial ring in one variable.
108156
Algebraic closure of $\mathbb{C}(x)$ is isomorphic to $\mathbb{C}$
24828
surjective immersion $\mathbb{R}^2 \to \mathbb{R}^2$ which is not a diffeomorphism
9793
Why is the image of a smooth embedding $f: N \to M$ an embedded submanifold?
143429
Kernel of ring homomorphism $k[X,Y] \rightarrow k[t^2, t^3]$
68728
Why does the natural ring homomorphism induce a surjective group homomorphism of units?
118903
The sup norm on $C[0,1]$ is not equivalent to another one, induced by some inner product