 12:59 AM
@quid - I pinged you just to make sure that you see barto's reply. @MartinSleziak thanks. I merged, and kept a synonym (for now, not sure if it's worth it, but I think it is one with not much risk.). Not sure whether it's possible that you will find the time to make a post on meta about this, but I thought I might remind you this issue:
Dec 9 '17 at 16:55, by quid
While being on that page I approved a bunch of syns. In the not too distant future I hope to go through the entire list. Then I'll revisit the max-min thing, too. 1:14 AM
Maybe tomorrow. Well, technically today. You get the idea.

9 hours later… 10:09 AM
A new tag was created by pointguard0.
0  Suppose $X_1, \dots, X_n \sim^{\text{iid}} \mathcal{N}(\theta, \sigma^2 I_p)$ and $\sigma^2$ is known. Define the risk as follows $$\mathcal{R}(\theta_1, \theta_2) = \mathbb{E} \|\theta_1 - \theta_2\|_2^2.$$ Then, it can be shown that $$\sup_{\overline{\theta} \in \Theta} \mathcal{R}(\overline... Minimax estimator In statistical decision theory, where we are faced with the problem of estimating a deterministic parameter (vector) θ ∈ Θ \theta \in \Theta } from observations x ∈ X , x\in {\mathcal {X}},} an estimator (estimation rule) δ M \delta ^{M}\,\!} is called minimax if its maximal... The word minimax refers to a few things in mathematics. WP: Minimax and Minimax (disambiguation). 6 hours later… 3:50 PM The tag was created by Rodrigo de Azevedo, including a short tag-excerpt. 3  Suppose$$ A = \left( \begin{array}{cc} 1 & 4 \\ 5 & 6 \end{array}\right) $$How do I calculate \|A\|_{\text{OP}}? I know the definition of operator norm, but I am clueless on how to calculate it for real example like this. Can somebody please give me a step-by-step instruction on how to d... 0  I was wondering if the spectral norm is a Lipschitz function with respect to the spectral norm. How can we prove whether it is or not? In other words, is$$\big| \|X\| - \|Y\| \big| \le L \|X-Y\|$$for some L? 4  Given symmetric matrices A_0, A_1, \dots, A_n \in \mathbb R^{m \times m}, let A(x) := A_0 + x_1 A_1 +\cdots + x_n A_n. How to formulate the following unconstrained spectral minimization problem as a semidefinite program?$$\min_{x \in \mathbb R^n} \|A(x)\|_2$$Can anyone please help on this... -1  I wonder if the 2-norm or spectral norm is also submultiplicative for non-square matrices, i.e.,$$\| A B \|_2 \leq \| A \|_2 \cdot \| B \|_2$$if the number of columns of A coincides with the number of rows of B. In the literature I can only find a statement about square matrices. Thank... 3  I was reading the use of semidefinite programs to formulate the matrix norm minimization but am having trouble trying to understand it. I'd also like to understand it at a more intuitive level. [Boyd and Vandenberghe: Convex optimization \S 4.6.3] Matrix norm minimization Let A(x... 21  This may be a trivial question yet I was unable to find an answer:$$\left \| A \right \| _2=\sqrt{\lambda_{\text{max}}(A^{^*}A)}=\sigma_{\text{max}}(A)$$where the spectral norm \left \| A \right \| _2 of a complex matrix A is defined as$$\text{max} \left\{ \|Ax\|_2 : \|x\| = 1 \right\}...

8  Is there an intuitive meaning for the spectral norm of a matrix? Why would an algorithm calculate the relative recovery in spectral norm between two images (i.e. one before the algorithm and the other after)? Thanks 4:16 PM
I realized that we only have but nothing for answers or posts generically. Not sure what to do. Maybe rename the existing tag?

2 hours later… 6:07 PM
@quid That sounds quite reasonably to me. (Perhaps and could be synonyms?)
Just for comparison, situation on Mathematics Meta is not ideal either: ther is tag (locked) - with synonym locking - and separate tags (locked-questions) and (locked-answers).