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1d
reviewed Approve Complexity of computing expansion of a newform level 18 weight 3 and character [3] - OEIS A116418
1d
comment p-groups with unique normal minimal subgroup
@YCor: I though the same thing; and $p$-groups with a unique subgroup of order $p$ (hence unique normal subgroup) must be either cyclic or generalized quaterniong (e.g., Theorem 5.46 in Rotman's "Introduction to the theory of groups" 4th edition). But there are $p$-groups with unique minimal normal subgroups that do not have unique minimal subgroups, e.g., the group of order $p^3$ and exponent $p$.
1d
comment applications of systems of linear equations
math.overflow is for research-level questions; this is a simple exercise on a first financial mathematics course. There are other sites where the question might be appropriate, such as math.stackexchange.
Feb
7
reviewed Approve What is a foliation and why should I care?
Feb
2
reviewed Reject What is the “right” universal property of the completion of a metric space?
Jan
28
comment How small can a set system containing a large subset of every set be?
Got it; (it should have been $c=1/(n+1)$, but I see that you want $c$ fixed and independent of $n$).
Jan
28
comment How small can a set system containing a large subset of every set be?
Excluding $A=\varnothing$, $S$ can have $n$ elements: take $S$ to be the set of all singletons, and take $c=n+1$. On the other hand, $S$ must contain all singletons, since taking $A$ to be a singleton forces $A'$ to be a singleton. So $S$ must have at least $n$ elements.
Jan
28
comment How small can a set system containing a large subset of every set be?
Surely you need to exclude $A=\varnothing$....
Jan
25
comment Is there a limit definition for the roots of a polynomial with arbitrary degree?
There are lots of known bounds on the roots of a given polynomial. See the Wikipedia article on "Properties of polynomial roots, section on "Bounds on (complex) polynomial roots".
Jan
18
comment Given $f(g(x))$ is convergent, what can be said about the convergence of $f(x)$ and $g(x)$?
My point is: which one are you talking about? You aren't clear. Are you asking about any (fixed) mode of convergence? What?
Jan
18
comment Given $f(g(x))$ is convergent, what can be said about the convergence of $f(x)$ and $g(x)$?
What type of convergence are you talking about? Pointwise? Uniform? etc.
Jan
6
revised What kind of group invariants exist?
wondeering, not wanderings
Dec
23
comment On group of automorphisms of direct product of nonabelian finite groups
See math.stackexchange.com/questions/420884/…
Dec
23
reviewed Approve “Harmonic oscillator” with $p$-Laplacian
Dec
23
reviewed Approve Name for algebra and its tensor products
Dec
15
reviewed Approve Noether Normalization
Dec
13
comment When is the equalizer of group homomorphisms a normal subgroup?
Since every subgroup of a group $G$ is an equalizer subgroup (even in the category of finite groups), there will be very few conditions you can place in general to guarantee that the equalizer will be normal, and most of them will be in terms of severely restricting the types of morphisms, or the type of group (e.g., obviously it will hold for any Dedekind group).
Dec
10
revised When does $\langle grg^{-1}|g\in G\rangle = \langle gsg^{-1}|g\in G\rangle$ imply $\langle r\rangle=\langle xsx^{-1}\rangle$?
edited title
Dec
10
revised When does $\langle grg^{-1}|g\in G\rangle = \langle gsg^{-1}|g\in G\rangle$ imply $\langle r\rangle=\langle xsx^{-1}\rangle$?
edited title
Dec
10
revised When does $\langle grg^{-1}|g\in G\rangle = \langle gsg^{-1}|g\in G\rangle$ imply $\langle r\rangle=\langle xsx^{-1}\rangle$?
rephase, clarify.