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Questions about the branch of algebra that deals with groups.

7 votes
1 answer
347 views

New relator in hurwitz group

I have found that $([a,b]^2[a,b^2])^n$ is a good relator to use in my search for quotients of $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^{10} \rangle$. For n<=5 $H := \langle a, b \ | \ a^2, b^3 …
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  • 2,811
0 votes
0 answers
221 views

Infinite quotient of Hurwitz Group

I am currently working through all the groups with two generators, and I am up to the group with presentation $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^9 \rangle$. I have found all the finite q …
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  • 2,811
1 vote
1 answer
177 views

Largest quotient of solvability length 2

I've been thinking about quotients of groups, and I know that the abelianization G/[G,G] is important, but what about other quotients? Specifically, what about the quotient G/[G,[G,G]]? Is that import …
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  • 2,811
6 votes
1 answer
501 views

A curious group presentation

$\DeclareMathOperator\PSL{PSL}$I'm studying the Hurwitz group $(2, 3, 7; 9)$, with presentation: $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^9 \rangle$. This group has $\PSL_2(8)$ as a quotient, …
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  • 2,811
7 votes
2 answers
961 views

Simplicity of infinite groups

Sorry about asking so many questions, but I am a bit further on in my classification, and I am up to the group $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^{10}, ([a,b]^4b)^7 \rangle$. It has no s …
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  • 2,811
5 votes
1 answer
730 views

Free metabelian group of rank 2

I was trying to find the free metabelian group of rank 2, and I realized that the wreath product of Z and Z is metabelian and has only 2 generators in its minimal generating set. I could not find a wa …
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  • 2,811
3 votes

Presentations of simple groups

The only groups where 1/l+1/m+1/n is greater than one are the cyclic groups, the dihedral groups, and the groups A(4), S(4), and A(5). Therefore, A(5) is the only simple groups where 1/l+1/m+1/n>1. As …
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  • 2,811
4 votes
1 answer
293 views

Is there a name for this (conjugacy class multiplication table)? [closed]

Sorry about asking so many questions, but I had an idea for my study of groups, and I wanted to know if it was already a thing people use. My idea is to make a multiplication table with all the conjug …
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  • 2,811
15 votes
1 answer
608 views

What is this quotient of the triangle 2-3-7 group?

I have been working with Hurwitz groups, and I came across the group $G := \langle a, b \ | \ a^2, b^3, (ab)^7, ([a,b]^2ab)^6 \rangle$. I'm trying to figure out exactly what this group is. I know it c …
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  • 2,811
0 votes
1 answer
159 views

The simple groups with an absolutely irreducible projective representations with small degrees

In the question "Simple Hurwitz Groups of order less than 10^7", it came up that all the Hurwitz groups with absolutely irreducible projective representations of degrees up to 7 over any field are det …
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3 votes
0 answers
195 views

Alternating quotients of (2,3,7;10)

It was shown that the only quotient of the group $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^{10} \rangle$ of the form PSL(2, q) is PSL(2, 41). That lead me to consider other families of simple g …
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11 votes
1 answer
457 views

Group theory conjecture on hurwitz groups

Conjecture: Let $p$ be a prime. Then the group $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^9, (([a,b]^4)b)^{2p} \rangle$ has a composition series of the form ${\rm PSL}(2,8) - {\rm Z}_p - {\r …
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  • 2,811
2 votes
1 answer
375 views

Quotients of Hurwitz group

Since my question at Simplicity of infinite groups was not answered (well, at least, my second question), instead of trying to find the isomorhism type of those groups, I will instead try to find the …
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  • 2,811
1 vote
1 answer
342 views

Help understanding a group

I was experimenting with various presentations for groups, and I stumbled upon $G := \langle a, b \ | \ a^2, b^3, (ab)^7, [aba,b]^6 \rangle$. I found that it has order 11741184, but the magma calculat …
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  • 2,811
2 votes
Accepted

Help understanding a group

Actually, I just figured it out. The groups $H := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^{28}, [aba,b]^6 \rangle$ and $I := \langle a, b \ | \ a^2, b^3, (ab)^7, [a,b]^{8}, [aba,b]^6 \rangle$ are …
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