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Rammus's user avatar
Rammus's user avatar
Rammus
  • Member for 9 years, 6 months
  • Last seen this week
19 votes

What's wrong with l'Hopital's rule?

6 votes
Accepted

Does this sequence reach infinity?

6 votes
Accepted

Use calculus to derive area of circle using n triangles

5 votes
Accepted

Upper bound for the trace of the product of a matrix and a positive matrix

4 votes

Proving that a set is empty (or is a subset to $\varnothing$)

4 votes

Does symmetry of $AB$ imply symmetry of $A^\dagger B$?

3 votes
Accepted

Let $T\in B(H)$ be such that $\langle Tx,x \rangle = 0$ for all $x\in H$. Prove that $T=0$.

3 votes
Accepted

Kronecker product vec trick but middle matrix is transposed

3 votes
Accepted

How to show the hermitian adjoint of two operator's kronecker product is equal to their hermitian adjoints' kronecker product?

3 votes
Accepted

where to start if you lack basics?

3 votes
Accepted

If a symmetric PSD matrix has a zero entry on the main diagonal, its determinant is zero

2 votes
Accepted

Are anticommuting involutory matrices Hermitian?

2 votes

What kind of curve is made of half circles?

2 votes

What is the probability of two out of three events happening?

2 votes
Accepted

Quantum information theory and nonlocal games

2 votes
Accepted

If $V$ is right-orthogonal, does it hold $\langle AV,BV\rangle_F=\langle A,B\rangle_F$?

2 votes
Accepted

What is $\max\langle x,Ax\rangle$ over subspaces non-invariant under $A$?

2 votes
Accepted

Writing Probability distribution in terms of a trace over a density matrix

2 votes
Accepted

Make a matrix symmetric and positive semi-definite if it already approximately is

2 votes

Question on positive semidefiniteness

2 votes
Accepted

matrix operator 2 norm inequality involving product of three matrices

2 votes
Accepted

Matrix for which $A^\ast A = 1$, but $A A^\ast \ne 1$ (or reversed)

2 votes
Accepted

Why $\omega\left[\begin{pmatrix} 0 &Q\\ R &0 \end{pmatrix}\right]\leq\omega\left[\begin{pmatrix} P &Q\\ R &S \end{pmatrix}\right]$?

2 votes
Accepted

Properties with matrices $A$, $B$, and $A-B$ being positive definite.

2 votes
Accepted

Is the convex hull of product channels strictly contained in the set of all channels

2 votes

binary matrix and product between a matrix and its transpose

2 votes
Accepted

Trace of operator defined on direct sum of two vector spaces

2 votes

Is $P+(I-P)C$ positive definite?

2 votes

Find $\alpha$ that minimizes $\|(I-\alpha H)^2 A\|$

2 votes
Accepted

Prove that $tr\Big(\sum_k E_k^\dagger E_k\rho\Big)=1$ for all $\rho$ implies $\sum_k E_k^\dagger E_k=I$