What is $\varphi(0)$?
119048
What is the Euler Totient of Zero?
137711
Alternative proof that $[\Bbb{Q}(\zeta_n) : \Bbb{Q} ]= \varphi(n)$ uses circular reasoning?
96355
What is the first order axiom characterizing a field having characteristic zero?
93606
Showing that $C[0,1]$ is not complete
21782
Is $\aleph_0 = \mathbb{N}$?
12402
Showing a function on $[0,1]$ is the zero function
53426
Proof of a formula involving Euler's totient function: $\varphi (mn) = \varphi (m) \varphi (n) \cdot \frac{d}{\varphi (d)}$
67394
How to interpret $\mathbb{P}(B|A)$ when $\mathbb{P}(A) = 0$
128381
Branches of $\log(z)$ on $\mathbb{C}\backslash(-\infty,0]$?
142740
If $\varphi \in E'$ and $A$ is convex and open then $\varphi (A)$ is an open interval
76110
Proving that the zero vector is unique
45216
Cardinality of $[0,1]$
52012
Is there exist a homemoorphism between either pair of $(0,1),(0,1],[0,1]$
42334
Does $\lambda$ $\mathbf u$ $= 0$ imply $\lambda = 0$ or $\mathbf u$ $= 0$?
14251
$P[X=x]=0$ when $X$ is continuous variable
72660
How can I show that $f$ must be zero if $\int fg$ is always zero?
33247
Does $f(0)=0$ and $\left|f^\prime(x)\right|\leq\left|f(x)\right|$ imply $f(x)=0$?