There is no endomorphism $\phi : \mathbb R^5 \to \mathbb R^5$ with $\ker \phi = \text{Im}\phi$
98225
Dimensions with Rank-Nullity question
97258
Give $\ker(\phi)$ for $\phi: \mathbb{Z} \to \mathbb{Z_7}$ such that $\phi(1)=4$
73573
image of polynomial map is not an algebraic set
52088
Isomorphism of an endomorphism ring, how can $R\cong R^2$?
93923
No surjective bounded linear map from $\ell^2(\mathbf{N})$ to $\ell^1(\mathbf{N})$
105333
Generated $\sigma$-algebras with cylinder set doesn't contain the space of continuous functions
131082
Proof that $\mathbb R/[0,1]$ and $\mathbb R$ are homeomorphic
7890
Prove the map $\Phi:G\to\operatorname{Aut}G$ with $g\mapsto (x\mapsto g^{-1}xg)$ is an homomorphism.
85586
Proving $\mathbb{Q}$ isn't homeomorphic to $\mathbb{Z}$
70198
Why this two spaces do not homeomorphic?
104505
Is every normal subgroup the kernel of some endomorphism?
92599
Prove there generally is no isomorphism between $R[x]/(x^2-a)$ and $R^2$
98696
Is the exponential map ever not injective?
151354
Why are there no non-trivial regular maps $\mathbb{P}^n \to \mathbb{P}^m$ when $n > m$?
155266
Is $\exp:\overline{\mathbb{M}}_n\to\mathbb{M}_n$ injective?
3775
How many maps $\phi:\Bbb{N}\to\Bbb{N}$ are there with $\phi(ab) = \phi(a)+\phi(b)$?
90010
Can we ascertain that there exists an epimorphism $G\rightarrow H$?