If $\langle T(x), x \rangle = 0$ for all $x$, must $T$ must be zero?
7813
In a complex vector space, $\langle Tx,x \rangle=0 \implies T = 0$
128932
Is my expansion of the state $| x \rangle$ correct?
3396
Find the case when $t^3$ never equals to any of the given
27901
Proving $\sum\limits_{i=1}^k | \langle x,v_i \rangle \langle y,v_i\rangle| \leq \|x\|\cdot \|y\|$
154612
$\int_{0}^{x} f(t) dt \ge {f(x)}$ holds or not on $[0,1]$
103870
$3.\lim_{n\to\infty}\langle x,e_n\rangle=?$
20503
Meaning of inner product $\langle \vec{r} | \psi(t)\rangle $
102871
$\langle r\rangle$ maximal $\iff r$ irreducible
151721
Uhlmann's Theorem: proof of $\text{tr}(A^{\dagger} B) = \langle m | A \otimes B |m\rangle $
56102
Prove that there is no non-zero linear operator on $\mathbb C^{2}$ such that $(\alpha | T\alpha) = 0$
65395
Prove that if $\operatorname{rank}(T) = \operatorname{rank}(T^2)$ then $R(T) \cap N(T) = \{0\}$
122213
Proving that if $\langle Ax,x\rangle =0$ for every $x$, then $A$ is the zero operator
61274
If $AA^T$ is the zero matrix, then $A$ is the zero matrix
152932
Proof: $\det\pmatrix{\langle v_i , v_j \rangle}\neq0$ $\iff \{v_1,\dots,v_n\}~\text{l.i.}$
52928
If $\mathrm{Tr}(A)=0$ then $T=R^{-1}AR$ has all entries on its main diagonal equal to $0$
128875
Expectation values of the position operator is equal to zero in case of even potentials?
66451
In a ring, how do we prove that a * 0 = 0?