Description of the group $1+J(FG),$ where $J(FG)$ is jacobson radical of the group ring $GF.$
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My group is $$G=(mathbb{Z}_3timesmathbb{Z}_3)rtimesmathbb{Z}_3= {a,b,c:a^3=b^3=c^3=e, ab=ba, ac=ca, cb=abc}.$$ which is non abelian group of order $27.$
Now my problem is whether the group $1+J(FG)$ is abelian or non-abelian and what is its exponent? Here $F$ is any finite field of characteristic $3.$ I only know that $(1+J(FG))^{27}=1,$ by using below proposition given in the book "The Jacobson radical of group algebras" by G.Karpilovsky.
$textbf{Proposition}$. Let $N$ be a normal subgroup of $G$ such that $G/N$ is $p$-solvable. If $|G/N|=np^a$ where $(p,n)=1$ then $$J(FG)^{p^a}subseteq FG.J(FN)subseteq J(FG)$$ In particular, if $G$ is $p$-solvable of order $np^a$ where $(p,n)=1,$ then $$J(FG)^{p^a}=0.$$
Please anyone try to help me . I will be very thankful. Thanks.
group-rings
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up vote
1
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My group is $$G=(mathbb{Z}_3timesmathbb{Z}_3)rtimesmathbb{Z}_3= {a,b,c:a^3=b^3=c^3=e, ab=ba, ac=ca, cb=abc}.$$ which is non abelian group of order $27.$
Now my problem is whether the group $1+J(FG)$ is abelian or non-abelian and what is its exponent? Here $F$ is any finite field of characteristic $3.$ I only know that $(1+J(FG))^{27}=1,$ by using below proposition given in the book "The Jacobson radical of group algebras" by G.Karpilovsky.
$textbf{Proposition}$. Let $N$ be a normal subgroup of $G$ such that $G/N$ is $p$-solvable. If $|G/N|=np^a$ where $(p,n)=1$ then $$J(FG)^{p^a}subseteq FG.J(FN)subseteq J(FG)$$ In particular, if $G$ is $p$-solvable of order $np^a$ where $(p,n)=1,$ then $$J(FG)^{p^a}=0.$$
Please anyone try to help me . I will be very thankful. Thanks.
group-rings
@rschwieb Please help me to solve it ....
– neelkanth
10 hours ago
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
My group is $$G=(mathbb{Z}_3timesmathbb{Z}_3)rtimesmathbb{Z}_3= {a,b,c:a^3=b^3=c^3=e, ab=ba, ac=ca, cb=abc}.$$ which is non abelian group of order $27.$
Now my problem is whether the group $1+J(FG)$ is abelian or non-abelian and what is its exponent? Here $F$ is any finite field of characteristic $3.$ I only know that $(1+J(FG))^{27}=1,$ by using below proposition given in the book "The Jacobson radical of group algebras" by G.Karpilovsky.
$textbf{Proposition}$. Let $N$ be a normal subgroup of $G$ such that $G/N$ is $p$-solvable. If $|G/N|=np^a$ where $(p,n)=1$ then $$J(FG)^{p^a}subseteq FG.J(FN)subseteq J(FG)$$ In particular, if $G$ is $p$-solvable of order $np^a$ where $(p,n)=1,$ then $$J(FG)^{p^a}=0.$$
Please anyone try to help me . I will be very thankful. Thanks.
group-rings
My group is $$G=(mathbb{Z}_3timesmathbb{Z}_3)rtimesmathbb{Z}_3= {a,b,c:a^3=b^3=c^3=e, ab=ba, ac=ca, cb=abc}.$$ which is non abelian group of order $27.$
Now my problem is whether the group $1+J(FG)$ is abelian or non-abelian and what is its exponent? Here $F$ is any finite field of characteristic $3.$ I only know that $(1+J(FG))^{27}=1,$ by using below proposition given in the book "The Jacobson radical of group algebras" by G.Karpilovsky.
$textbf{Proposition}$. Let $N$ be a normal subgroup of $G$ such that $G/N$ is $p$-solvable. If $|G/N|=np^a$ where $(p,n)=1$ then $$J(FG)^{p^a}subseteq FG.J(FN)subseteq J(FG)$$ In particular, if $G$ is $p$-solvable of order $np^a$ where $(p,n)=1,$ then $$J(FG)^{p^a}=0.$$
Please anyone try to help me . I will be very thankful. Thanks.
group-rings
group-rings
edited 8 hours ago
asked 10 hours ago
neelkanth
1,9711925
1,9711925
@rschwieb Please help me to solve it ....
– neelkanth
10 hours ago
add a comment |
@rschwieb Please help me to solve it ....
– neelkanth
10 hours ago
@rschwieb Please help me to solve it ....
– neelkanth
10 hours ago
@rschwieb Please help me to solve it ....
– neelkanth
10 hours ago
add a comment |
1 Answer
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1
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It seems to me that since $J(FG)$ is maximal and contains the augmentation ideal, it contains $a-1, b-1$ for any elements $a,bin G$. In particular, if you select $a,b$ such that $abneq ba$ this is true.
Then $a=a-1+1$ and $b=b-1+1$ are both in $1+J(FG)$ and they don't commute.
I'm not sure why anything harder is necessary...
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
|
show 1 more comment
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
1
down vote
accepted
It seems to me that since $J(FG)$ is maximal and contains the augmentation ideal, it contains $a-1, b-1$ for any elements $a,bin G$. In particular, if you select $a,b$ such that $abneq ba$ this is true.
Then $a=a-1+1$ and $b=b-1+1$ are both in $1+J(FG)$ and they don't commute.
I'm not sure why anything harder is necessary...
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
|
show 1 more comment
up vote
1
down vote
accepted
It seems to me that since $J(FG)$ is maximal and contains the augmentation ideal, it contains $a-1, b-1$ for any elements $a,bin G$. In particular, if you select $a,b$ such that $abneq ba$ this is true.
Then $a=a-1+1$ and $b=b-1+1$ are both in $1+J(FG)$ and they don't commute.
I'm not sure why anything harder is necessary...
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
|
show 1 more comment
up vote
1
down vote
accepted
up vote
1
down vote
accepted
It seems to me that since $J(FG)$ is maximal and contains the augmentation ideal, it contains $a-1, b-1$ for any elements $a,bin G$. In particular, if you select $a,b$ such that $abneq ba$ this is true.
Then $a=a-1+1$ and $b=b-1+1$ are both in $1+J(FG)$ and they don't commute.
I'm not sure why anything harder is necessary...
It seems to me that since $J(FG)$ is maximal and contains the augmentation ideal, it contains $a-1, b-1$ for any elements $a,bin G$. In particular, if you select $a,b$ such that $abneq ba$ this is true.
Then $a=a-1+1$ and $b=b-1+1$ are both in $1+J(FG)$ and they don't commute.
I'm not sure why anything harder is necessary...
answered 9 hours ago
rschwieb
103k1299238
103k1299238
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
|
show 1 more comment
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
Thanks sir ....actually as you discussed in math.stackexchange.com/questions/2049645/… according to it J(FG ) is same as augmentation ideal as unique sylow subgroup is group itself so right side group being trivial and hence kernel is augmentation ideal.
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
my last question is about exponent of group $1+J(FG)$...thanks ...
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
Can i say its exponent must be $27$ as $3$ and $9$ order groups are always abelian.?
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
So $1+J(FG)$ is a non abelian group of exponent $27?$
– neelkanth
9 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
@neelkanth You asked if it was abelian or not, and I'm saying it doesn't appear to be. You do see that the map $xto 1+x$ is one to one, right? And it is into hard to count the elements of the augmentation ideal. In this case it's a subspace of codimension $1$. Does that answer your question?
– rschwieb
8 hours ago
|
show 1 more comment
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@rschwieb Please help me to solve it ....
– neelkanth
10 hours ago