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Questions on group theory which concern finite groups.

12 votes

Solvable transitive groups of prime degree

This is exercise 7.2.12 of Robinson's Course in the Theory of Groups, page 195 in the first edition. A transitive subgroup of prime degree is primitive, and primitive solvable groups have a regular n …
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12 votes

Minimal normal subgroups of a finite group

Here is a little survey of the "bottom" of finite groups. It includes an answer to (2) in the case of finite nilpotent groups, and a correction to an anonymous comment. The subgroup generated by the …
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13 votes
Accepted

Applications of fusion systems

Lots of results in group cohomology only have topological proofs using the techniques of Bob Oliver and his (generalized) collaborators. For instance, many results along the lines of "controls fusion …
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4 votes
1 answer
131 views

Generalized system normalizer for insoluble finite groups

For a finite group $G$ is there a subgroup $H$ such that for every chief factor $K/L$ of $G$ one has: $G = K C_G(K/L)$ and $K \leq HL$ (so $K/L$ is inner and covered by $H$) $G \neq K C_G(K/L)$ and …
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3 votes

Common Computations in Group Cohomology

You might be considering a special case of the Schur-Zassenhaus theorem. If A is a normal Hall-subgroup of G, then A has a complement B, and all complements B are conjugate under the action of G. Th …
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17 votes
Accepted

Results about the order of a group forcing a particular property.

The numbers n such that every group of order n is cyclic, abelian, nilpotent, supersolvable, or solvable are known. Most are described in an easy to read survey: Pakianathan, Jonathan; Shankar, Kris …
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7 votes

Finite groups with centerless quotients

The quotients of a finite group, G/N have minimal normal subgroups K/N. These are called chief factors. Chief factors are divided into two kinds, central chief factors and eccentric chief factors. …
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3 votes

Real representation of finite groups

Some of the other answers omit several details and I had already written this on another forum. At any rate, perhaps the example would be useful: More or less yes, though for larger groups it is not …
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10 votes
Accepted

A condition on finite groups

Short answer: a typical example is G=SL(2,5), H = Z(G) = Z/2Z. If G/H and H are coprime and satisfy the condition, the G = G/H × H is quite dull. I'll assume you find this interesting, and want …
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11 votes

How many conjugacy classes of subgroups does GL(2,p) have?

This question is reasonably hard, but important. A very clear and explicit answer is given in: Flannery, D. L.; O'Brien, E. A. "Linear groups of small degree over finite fields." Internat. J. Algebr …
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3 votes
Accepted

Are there finite metabelian groups with arbitrarily many character degrees?

Sure, you just take direct products of metabelian groups with different character degrees: cd(G×H) = cd(G)×cd(H) and (G×H)′ = G′×H′. I suggest taking G(p) = AGL(1,p) = Hol(p) to be the normalizer of …
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3 votes

List of centers of finite groups

I don't know of a resource with such a list, though you could easily make one with programs such as GAP or Magma. Since it is reasonably easy and interesting to analyze this problem, I'll outline how …
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3 votes

Are there any abelian 2 groups with Complete Holomorphs Other than $C^2_2$ and $C^4_2$?

I believe the holomorph of the elementary abelian group of order 2n is complete unless n=1 or 3. It is called AGL(n,2), the affine general linear group of dimension n over the field of size 2. In ot …
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8 votes
Accepted

The X-series (for groups)

This is called a chief series or principal series. The quotients of the terms in the series are called chief factors, and the length of the series is called the chief length. Non-isomorphic groups c …
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13 votes
Accepted

The maximum order of finite subgroups in $GL(n,Q)$

Feit published his paper in the proceedings of the first Jamaican conference, MR1484185. He defines M(n,K) to be the group of monomial matrices whose entries are roots of unity. M(n,Q) is the group …
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