Questions tagged [solvable-groups]
For questions on solvable groups, their properties, and structure.
577 questions
2 votes
0 answers
34 views
An inclusion-exclusion-like inequality for the Hirsch length
Let $G$ be a virtually polycyclic group with subgroups $H$ and $K$. Let $h(\,.)$ denote the Hirsch length. Does the inequality $$h(G) \geq h(H) + h(K) - h(H \cap K)$$ always hold? (I've found this ...
2 votes
0 answers
32 views
Generating a finite non-solvable group with an element and its conjugate
It is known that for any finite simple group $G$ there exist two elements $a,b\in G$ such that $a$ and $b$ are conjugates in $G$ and $\langle a, b \rangle=G$. My question: Is it true for any finite ...
4 votes
2 answers
190 views
Wang-Chen theorem on solvability?
There is a theorem by Wang and Chen that says: when the finite group $A$ acts via automorphisms on the finite group $G$ with $|A|$ and $|G|$ coprime, and $C_G(A)$ is either odd-order or nilpotent, ...
5 votes
0 answers
53 views
Solving Isaacs FGT problem 3C.8 using Carter subgroups
In Finite Group Theory by Isaacs, problem 3C.8 essentially asks: show two nilpotent injectors in a finite solvable group $G$ are conjugate. Isaacs uses a non-standard definition of nilpotent injector, ...
4 votes
1 answer
114 views
A Query on Commutator Subgroup
Let $G$ be a finite non-nilpotent, solvable group such that its commutator subgroup $G'$ is the unique minimal normal subgroup of $G$. Is it necessarily true that $G/G'$ is cyclic? I believe it is not ...
2 votes
0 answers
89 views
Can the normal subgroups of $G \over \Phi(G)$ be determined from those of $G$
Let $G$ be a finite group, and let $\Phi(G)$ denote its Frattini subgroup. Since $\Phi(G)$ is contained in every maximal subgroup of $G$, it is natural to ask about the relationship between the normal ...
0 votes
0 answers
48 views
Approach to showing that the group of invertible upper-triangular matrices over a finite field is soluble [duplicate]
Let $F$ be a finite field and let $G$ be the subgroup of upper triangular matrices in $GL_n(F)$. I am working through an exercise to show that $G$ is a soluble group. The exercise has the following ...
0 votes
1 answer
46 views
Can a local extremum be solvable by radicals without the critical point being so?
Let $f(x)$ be a rational function over $\mathbb{Q}$. Suppose that $(x_0,f(x_0))$ is a local extremum of the function, so in particular, $x_0$ is a root of $f'(x)$. Is it possible for $f(x_0)$ to be ...
1 vote
0 answers
51 views
Elementary subgroups of $\operatorname{Isom}^+(\mathbb{H}^2)$ are solvable.
I was reading the proof of Proposition 12.31 of Roberto Frigerio in "Bounded cohomology of discrete groups": Proposition $12.31$. Let $ρ: \Gamma g → \operatorname{Isom}^+(\mathbb{H}^2)$ be ...
1 vote
1 answer
55 views
Classification of the solvability-forcing numbers
A positive integer $n$ is said to be a solvability-forcing number if every group of order $n$ is solvable. In here it is stated that $n$ is a solvability-forcing number if and only if no divisor of $n$...
1 vote
1 answer
91 views
If $S$ and $T$ are solvable subgroups of $G$ with $S\trianglelefteq G$, then $ST$ is solvable.
This is Exercise 5.18(i) from Rotman's An Introduction to the Theory of Groups. I had two ideas for trying to solve this exercise. The first is to take solvable series $S = S_0 \geqslant...\geqslant ...
6 votes
2 answers
807 views
A group generated by an element and its conjugate must be solvable.
Let $G$ be a finite group such that $G =\langle x,y\rangle$ where $x$ and $y$ are conjugates in $G$. Does this necessarily imply that $G$ is solvable? P.S. I can not give any concrete reason behind my ...
3 votes
1 answer
82 views
Brief proof of Embedding to algebraic closure perserve solvable by radical
Lang’s Algebra in p.308 is written as follows, for any embedding $\sigma$ of $E$ in $E^*$ over $k$, extension $\sigma E/k$ is also solvable by radical, it is pretty brief Hence, my proof of this two ...
1 vote
0 answers
51 views
Supersolvability of some triangular groups
Let $T(n,R) < \mathrm{GL}(n,R)$ be a group consisting of upper (or lower) triangular $n \times n$ matrices over a ring $R$. It is clear that when $R$ is a field, $T(n,R)$ is soluble. (Hint: ...
0 votes
1 answer
93 views
Any finite solvable group with $mp+1$ $p$-Sylows, $1 \leq m<p$, $p>2$ such that $mp+1$ is neither $q^a$ nor $(qt)^a$ for some $q,t$ primes?
Given $p>2$ prime, is there any finite solvable group with $mp+1$ Sylow $p$-subgroups with $1 \leq m < p$ such that $mp+1$ is neither a prime power nor $(qt)^a$ for $q,t$ primes? I'm looking for ...