Does alternating group $A_5$ is a subgroup of $GL(4,mathbb Z)$?
Does alternating group $A_5$ is a subgroup of $GL(4,mathbb Z)$? I know $A_5$ has a 4-dimensional complex representation. But how to prove $A_5$ is a subgroup or not of $GL(4, mathbb Z)$?
In case $GL(4, mathbb Z)$ has a subgroup isomorphic to $A_5$, then I would like to know corresponding generators of that subgroup?
I want to know how many subgroups are there in $GL(4, Bbb Z)$ isomorphic to $A_5$. Is there a unique one?
Thank you so much in advance.
group-theory representation-theory
add a comment |
Does alternating group $A_5$ is a subgroup of $GL(4,mathbb Z)$? I know $A_5$ has a 4-dimensional complex representation. But how to prove $A_5$ is a subgroup or not of $GL(4, mathbb Z)$?
In case $GL(4, mathbb Z)$ has a subgroup isomorphic to $A_5$, then I would like to know corresponding generators of that subgroup?
I want to know how many subgroups are there in $GL(4, Bbb Z)$ isomorphic to $A_5$. Is there a unique one?
Thank you so much in advance.
group-theory representation-theory
add a comment |
Does alternating group $A_5$ is a subgroup of $GL(4,mathbb Z)$? I know $A_5$ has a 4-dimensional complex representation. But how to prove $A_5$ is a subgroup or not of $GL(4, mathbb Z)$?
In case $GL(4, mathbb Z)$ has a subgroup isomorphic to $A_5$, then I would like to know corresponding generators of that subgroup?
I want to know how many subgroups are there in $GL(4, Bbb Z)$ isomorphic to $A_5$. Is there a unique one?
Thank you so much in advance.
group-theory representation-theory
Does alternating group $A_5$ is a subgroup of $GL(4,mathbb Z)$? I know $A_5$ has a 4-dimensional complex representation. But how to prove $A_5$ is a subgroup or not of $GL(4, mathbb Z)$?
In case $GL(4, mathbb Z)$ has a subgroup isomorphic to $A_5$, then I would like to know corresponding generators of that subgroup?
I want to know how many subgroups are there in $GL(4, Bbb Z)$ isomorphic to $A_5$. Is there a unique one?
Thank you so much in advance.
group-theory representation-theory
group-theory representation-theory
edited 7 hours ago
asked 23 hours ago
mathstudent
324
324
add a comment |
add a comment |
1 Answer
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For any $n$, $S_n$ embeds in $GL(n-1,Bbb Z)$. Therefore $A_n$ does too.
Consider the vectors $v_1,ldots,v_n$ where $v_1,ldots,v_{n-1}$
are the standard unit vectors in $Bbb Z^{n-1}$ and $v_n=-v_1-cdots-v_{n-1}$.
By definition $v_1+cdots+v_n=0$. For each permutation $tauin S_n$, there's
a unique endomorphism of $Bbb Z^{n-1}$ taking each $v_k$ to $v_{tau(k)}$
(this works due to $v_1+cdots+v_n=0$). So $S_n$ embeds into $text{Aut}(
Bbb Z^{n-1})
=GL(n-1,Bbb Z)$.
In fact $A_n$ will embed in $SL(n-1,Bbb Z)$.
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
|
show 4 more comments
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1 Answer
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1 Answer
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active
oldest
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active
oldest
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active
oldest
votes
For any $n$, $S_n$ embeds in $GL(n-1,Bbb Z)$. Therefore $A_n$ does too.
Consider the vectors $v_1,ldots,v_n$ where $v_1,ldots,v_{n-1}$
are the standard unit vectors in $Bbb Z^{n-1}$ and $v_n=-v_1-cdots-v_{n-1}$.
By definition $v_1+cdots+v_n=0$. For each permutation $tauin S_n$, there's
a unique endomorphism of $Bbb Z^{n-1}$ taking each $v_k$ to $v_{tau(k)}$
(this works due to $v_1+cdots+v_n=0$). So $S_n$ embeds into $text{Aut}(
Bbb Z^{n-1})
=GL(n-1,Bbb Z)$.
In fact $A_n$ will embed in $SL(n-1,Bbb Z)$.
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
|
show 4 more comments
For any $n$, $S_n$ embeds in $GL(n-1,Bbb Z)$. Therefore $A_n$ does too.
Consider the vectors $v_1,ldots,v_n$ where $v_1,ldots,v_{n-1}$
are the standard unit vectors in $Bbb Z^{n-1}$ and $v_n=-v_1-cdots-v_{n-1}$.
By definition $v_1+cdots+v_n=0$. For each permutation $tauin S_n$, there's
a unique endomorphism of $Bbb Z^{n-1}$ taking each $v_k$ to $v_{tau(k)}$
(this works due to $v_1+cdots+v_n=0$). So $S_n$ embeds into $text{Aut}(
Bbb Z^{n-1})
=GL(n-1,Bbb Z)$.
In fact $A_n$ will embed in $SL(n-1,Bbb Z)$.
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
|
show 4 more comments
For any $n$, $S_n$ embeds in $GL(n-1,Bbb Z)$. Therefore $A_n$ does too.
Consider the vectors $v_1,ldots,v_n$ where $v_1,ldots,v_{n-1}$
are the standard unit vectors in $Bbb Z^{n-1}$ and $v_n=-v_1-cdots-v_{n-1}$.
By definition $v_1+cdots+v_n=0$. For each permutation $tauin S_n$, there's
a unique endomorphism of $Bbb Z^{n-1}$ taking each $v_k$ to $v_{tau(k)}$
(this works due to $v_1+cdots+v_n=0$). So $S_n$ embeds into $text{Aut}(
Bbb Z^{n-1})
=GL(n-1,Bbb Z)$.
In fact $A_n$ will embed in $SL(n-1,Bbb Z)$.
For any $n$, $S_n$ embeds in $GL(n-1,Bbb Z)$. Therefore $A_n$ does too.
Consider the vectors $v_1,ldots,v_n$ where $v_1,ldots,v_{n-1}$
are the standard unit vectors in $Bbb Z^{n-1}$ and $v_n=-v_1-cdots-v_{n-1}$.
By definition $v_1+cdots+v_n=0$. For each permutation $tauin S_n$, there's
a unique endomorphism of $Bbb Z^{n-1}$ taking each $v_k$ to $v_{tau(k)}$
(this works due to $v_1+cdots+v_n=0$). So $S_n$ embeds into $text{Aut}(
Bbb Z^{n-1})
=GL(n-1,Bbb Z)$.
In fact $A_n$ will embed in $SL(n-1,Bbb Z)$.
answered 23 hours ago
Lord Shark the Unknown
101k958132
101k958132
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
|
show 4 more comments
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
Thanks. I would like to know corresponding generators of the subgroup of $GL(4, mathbb Z)$ that is isomorphic to $A_5$ if possible.
– mathstudent
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
What are your favourite generators of $A_5$? @mathstudent
– Lord Shark the Unknown
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
Generators of $A_5$: $<(1 2)(3 4), (1 2 3 4 5)>$. Thanks.
– mathstudent
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
$(1,2,3,4,5)$ maps to $pmatrix{0&0&0&-1\1&0&0&-1\0&1&0&-1\0&0&1&-1}$ etc.
– Lord Shark the Unknown
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
Does $(1,2,5,3,4)$ maps to $pmatrix{0&-1&0&1\1&-1&0&0\0&-1&1&0\0&-1&0&0}$ and $(1,2)(3,4)$ maps to $pmatrix{0&1&0&0\1&0&0&0\0&0&0&1\0&0&1&0}$ ?
– mathstudent
22 hours ago
|
show 4 more comments
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