Prove that the isomorphism between vector spaces and their duals is not natural
54333
In categorical terms, why is there no canonical isomorphism from a finite dimensional vector space to its dual?
86015
$\mathbb Q[x]/(x^2+1)$ is not isomorphic to $\mathbb Q[x]/(x^2+2)$
137873
Problems that involves two facts in the definition of vector spaces
152212
Prove that the natural map $\alpha : \text{Hom}(X,\text{Spec} A) \rightarrow \text{Hom}(A,\Gamma(X,\mathcal{O}_X))$ is an isomorphism
107389
Show that the vector space of real functions is not finitely spanned
128229
Proving that the transformation obtained from an adjoint pair is natural
53850
Proof that every normed vector space is a topological vector space
42362
Show that the dual space of the vector space of all polynomials is isomorphic to the infinite-dimensional Euclidean vector space over the reals
66866
Algebraic dual of $\mathbb{R}^{\mathbb{N}}$
64130
Prove that $\mathbb{Q}^{\times}$ not isomorphic to $\mathbb{Z}^{n}$
146339
Proof of -(-v)=v in a vector space
131993
Prove that vector space and dual space have same dimension
109632
Show reflexive normed vector space is a Banach space
99938
Is the conjugation map always an isomorphism?
102371
Proving that two vector spaces of equal dimension are isomorphic
88474
$\mathbb{A}^{2}$ not isomorphic to affine space minus the origin
34798
Example of element of double dual that is not an evaluation map