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Q&A for professional mathematicians
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Let $A$ be a $C^*$-algebra and $(a_{ij}) \in M_n(A)$ be a positive matrix. Does there exist a constant $C \ge 0$ (not depending on the $a_{ij}$) such that $$\lVert(a_{ij})\rVert \le C \Bigl\lVert\s...
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Hottest Questions Today - MathOverflow
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Mathoverflow.net news digest
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0 days
Number of subgroups in a semidirect product
Let $G$ be a finite group and $Sub(G)$ denote the number of subgroups of $G$ including the trivial subgroup and $G$ itself. I believe the following is true:
$Sub(H \times K)\leq Sub(H \rtimes K)$ for all finite groups $H$ and $K$ with coprime orders.
However, I was not able to prove it, may be due to lack of Goursat-like results in semidirect products. I tried to use the results of a paper by V.M.Usenko. But I could not manage to do it. Any counterexample or a way leading to the proof will be helpful... -
0 days
Decoding this recursive structure notation
I encountered this mathematical structure but need helpdecoding the notation:
[T = \prod_{i=1}^{\infty} \mathbb{N}]
with hierarchy levels: -
0 days
Does there exist an analytic continuation into a region containing infinitely ma...
Let f be a function in the Hardy space H^2(\mathbb{C}^+). Consider a region \Omega \subset \mathbb{C} that contains infinitely many zeros of f, where neither the density nor the distribution of these zeros is known a priori.
The question is:
Does there exist an analytic continuation of f into \Omega under such minimal assumptions on the zeros?... -
0 days
Is this type of dual “generator–filter” variational structure already known in g...
I am studying a variational framework that I call a generator–filter transform (GFT), and I would like to understand whether the mathematical structure falls inside an existing branch of geometry (e.g., symplectic, Kähler, information geometry, topos...
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