If $A\oplus B\approx A$ then $B=0$?
35188
Counterexample: $G \times K \cong H \times K \implies G \cong H$
55577
Why is $\frac{1}{\infty } \approx 0 $ and $ \frac{1}{0} = {\infty}$?
83337
If $A ∈M_n(C)$ is such that $(Ax,x) = 0$ for all $x ∈C^n$, then $A = 0$
99458
Suppose $\int_{[a,b]}f=0,\text{ then }f(x)=0 \forall x\in[a,b]$
28391
Prove the compactness of a set B
64320
Prove that if $0<a<Pr(A)$ then there exists $B\subset A$ such that $Pr(B)=a$
32180
Why is "$A$ unless $B$" equivalent to $A \lor B$?
138283
$|(a,b)| = |\Bbb R|$ ? Cardinality of any open interval
155884
What are the conditions on $\text{tr}(AB) \leq \text{tr(A)} \text{tr(B)}$ to be true?
42853
If $f \geq 0$ is continuous and $\int_{a}^{b} f(x) \, dx = 0$, then $f =0$
92975
Does $a^n \mid b^n$ imply $a\mid b$?
116389
If $\exp(t(A + B)) = \exp(tA) \exp(tB)$ for all $t \geq 0$ then $A,B$ commute
88690
$\int_a^b f(x)\mathrm dx=0$ for all $-\infty<a<b<\infty$ a,b rational implies $f=0$ a.e
66451
In a ring, how do we prove that a * 0 = 0?
74792
$(X,\tau)$ needs to be $T_1$ in order to guarantee that $A'$ is closed?
153355
Given $S \in B(Y^{*}, X^{*})$, does there exist $T\in B(X,Y)$ such that $S=T^{*}$?
151168
dist$(x,A)=0$ if and only if $x\in \overline{A}$ (closure of $A$)