Difference between $\mathbb{F}(a)$ and $\mathbb{F}[a]$
138256
What's the difference between $\mathbb{Q}[\sqrt{-d}]$ and $\mathbb{Q}(\sqrt{-d})$?
145077
A continuous bijection $f:\mathbb{R}\to \mathbb{R}$ is an homeomorphism?
86015
$\mathbb Q[x]/(x^2+1)$ is not isomorphic to $\mathbb Q[x]/(x^2+2)$
155618
Slightly changing the formal definition of continuity of $f: \mathbb{R} \to \mathbb{R}$?
126821
Let $f:[0,1]\to \mathbb{R}$. Show that $\{a \in [0,1]: f(a)\neq 0\} = \bigcup_{n=1}^{\infty} \{a \in [0,1]: |f(a)|\geq 1/n\}$
83798
Does $A$ a UFD imply that  $A[T]$ is also a UFD?
45218
Comparing the two cardinals $\aleph_0^{\aleph_0}$ and $2^{\aleph_0}$
107842
Behaviour of ($\overline{a}_n)_{n=1}^{\infty}$ and ($\underline{a}_n)_{n=1}^{\infty}$
138419
Sigma algebra and algebra difference
149095
$f(\mathbb{R}\setminus \mathbb{Q}) \subseteq \mathbb{Q}$ and $f(\mathbb{Q}) \subseteq \mathbb{R}\setminus \mathbb{Q}$ imply that $f$ is not continuous
12272
Why $a$ is not an essential singularity and how $f$ can be extended
74453
Injective and Surjective Functions
83595
Proving that $\mathbb{A}=\{\alpha \in \mathbb{C}: \alpha \text{ is algebraic over } \mathbb{Q} \}$ is not a finite extension
147627
Relation between condition numbers $\kappa(A^T A)$ and $\kappa(A)$
13575
Need help for proving that: $f(f^{-1}(A)) ⊆ A$
53432
What is the algebraic closure of $\mathbb F_q$?
80199
Do we have always $f(A \cap B) = f(A) \cap f(B)$?