Non-abelian group in which $forall_{a,bin G} (ab)^3=a^3b^3$ [duplicate]












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  • If a group satisfies $x^3=1$ for all $x$, is it necessarily abelian?

    1 answer




Give an example of a non-abelian group, in which $(ab)^3=a^3b^3$ for every element $a,b$ in $G$.



I understand that such a group should be of order divisible by 3 (see Problem from Herstein on group theory). Also, it is easily seen that $(ab)^3=a^3b^3 iff (ba)^2=a^2b^2$. But I can't come up with one single example.










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marked as duplicate by Jack Schmidt, Hagen von Eitzen, user61527, Andrew D. Hwang, Davide Giraudo Feb 16 '14 at 18:12


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  • 2




    $begingroup$
    Any nonabelian group of exponent 3, for example.
    $endgroup$
    – Najib Idrissi
    Feb 16 '14 at 16:38
















1












$begingroup$



This question already has an answer here:




  • If a group satisfies $x^3=1$ for all $x$, is it necessarily abelian?

    1 answer




Give an example of a non-abelian group, in which $(ab)^3=a^3b^3$ for every element $a,b$ in $G$.



I understand that such a group should be of order divisible by 3 (see Problem from Herstein on group theory). Also, it is easily seen that $(ab)^3=a^3b^3 iff (ba)^2=a^2b^2$. But I can't come up with one single example.










share|cite|improve this question











$endgroup$



marked as duplicate by Jack Schmidt, Hagen von Eitzen, user61527, Andrew D. Hwang, Davide Giraudo Feb 16 '14 at 18:12


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.














  • 2




    $begingroup$
    Any nonabelian group of exponent 3, for example.
    $endgroup$
    – Najib Idrissi
    Feb 16 '14 at 16:38














1












1








1


0



$begingroup$



This question already has an answer here:




  • If a group satisfies $x^3=1$ for all $x$, is it necessarily abelian?

    1 answer




Give an example of a non-abelian group, in which $(ab)^3=a^3b^3$ for every element $a,b$ in $G$.



I understand that such a group should be of order divisible by 3 (see Problem from Herstein on group theory). Also, it is easily seen that $(ab)^3=a^3b^3 iff (ba)^2=a^2b^2$. But I can't come up with one single example.










share|cite|improve this question











$endgroup$





This question already has an answer here:




  • If a group satisfies $x^3=1$ for all $x$, is it necessarily abelian?

    1 answer




Give an example of a non-abelian group, in which $(ab)^3=a^3b^3$ for every element $a,b$ in $G$.



I understand that such a group should be of order divisible by 3 (see Problem from Herstein on group theory). Also, it is easily seen that $(ab)^3=a^3b^3 iff (ba)^2=a^2b^2$. But I can't come up with one single example.





This question already has an answer here:




  • If a group satisfies $x^3=1$ for all $x$, is it necessarily abelian?

    1 answer








group-theory abelian-groups






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edited Apr 13 '17 at 12:20









Community

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asked Feb 16 '14 at 16:18









UntitledUntitled

183111




183111




marked as duplicate by Jack Schmidt, Hagen von Eitzen, user61527, Andrew D. Hwang, Davide Giraudo Feb 16 '14 at 18:12


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.









marked as duplicate by Jack Schmidt, Hagen von Eitzen, user61527, Andrew D. Hwang, Davide Giraudo Feb 16 '14 at 18:12


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.










  • 2




    $begingroup$
    Any nonabelian group of exponent 3, for example.
    $endgroup$
    – Najib Idrissi
    Feb 16 '14 at 16:38














  • 2




    $begingroup$
    Any nonabelian group of exponent 3, for example.
    $endgroup$
    – Najib Idrissi
    Feb 16 '14 at 16:38








2




2




$begingroup$
Any nonabelian group of exponent 3, for example.
$endgroup$
– Najib Idrissi
Feb 16 '14 at 16:38




$begingroup$
Any nonabelian group of exponent 3, for example.
$endgroup$
– Najib Idrissi
Feb 16 '14 at 16:38










1 Answer
1






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oldest

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1












$begingroup$

Hint: try the group of triangular $3 times 3$ matrices over the field with 3 elements, with 1's on the diagonal. This group has exponent 3, that is for every $g in G$, it holds that $g^3=1$. Can you see that $|G|=27$?






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$endgroup$













  • $begingroup$
    I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 16:50












  • $begingroup$
    Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
    $endgroup$
    – Nicky Hekster
    Feb 16 '14 at 17:04










  • $begingroup$
    Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 17:11




















1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

Hint: try the group of triangular $3 times 3$ matrices over the field with 3 elements, with 1's on the diagonal. This group has exponent 3, that is for every $g in G$, it holds that $g^3=1$. Can you see that $|G|=27$?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 16:50












  • $begingroup$
    Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
    $endgroup$
    – Nicky Hekster
    Feb 16 '14 at 17:04










  • $begingroup$
    Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 17:11


















1












$begingroup$

Hint: try the group of triangular $3 times 3$ matrices over the field with 3 elements, with 1's on the diagonal. This group has exponent 3, that is for every $g in G$, it holds that $g^3=1$. Can you see that $|G|=27$?






share|cite|improve this answer









$endgroup$













  • $begingroup$
    I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 16:50












  • $begingroup$
    Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
    $endgroup$
    – Nicky Hekster
    Feb 16 '14 at 17:04










  • $begingroup$
    Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 17:11
















1












1








1





$begingroup$

Hint: try the group of triangular $3 times 3$ matrices over the field with 3 elements, with 1's on the diagonal. This group has exponent 3, that is for every $g in G$, it holds that $g^3=1$. Can you see that $|G|=27$?






share|cite|improve this answer









$endgroup$



Hint: try the group of triangular $3 times 3$ matrices over the field with 3 elements, with 1's on the diagonal. This group has exponent 3, that is for every $g in G$, it holds that $g^3=1$. Can you see that $|G|=27$?







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Feb 16 '14 at 16:33









Nicky HeksterNicky Hekster

28.4k53456




28.4k53456












  • $begingroup$
    I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 16:50












  • $begingroup$
    Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
    $endgroup$
    – Nicky Hekster
    Feb 16 '14 at 17:04










  • $begingroup$
    Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 17:11




















  • $begingroup$
    I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 16:50












  • $begingroup$
    Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
    $endgroup$
    – Nicky Hekster
    Feb 16 '14 at 17:04










  • $begingroup$
    Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
    $endgroup$
    – Omnomnomnom
    Feb 16 '14 at 17:11


















$begingroup$
I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
$endgroup$
– Omnomnomnom
Feb 16 '14 at 16:50






$begingroup$
I'd just like to add: as evidence that $G$ is not abelian, note that $A = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 1 \ 0 & 0 & 1 \}$ and $B = pmatrix{ 1 & 1 & 0 \ 0 & 1 & 2 \ 0 & 0 & 1 \}$ satisfy $AB neq BA$.
$endgroup$
– Omnomnomnom
Feb 16 '14 at 16:50














$begingroup$
Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
$endgroup$
– Nicky Hekster
Feb 16 '14 at 17:04




$begingroup$
Yes good remark - on the other hand, I was hoping that the OP would figure that (non-abelianess) out for him/herself.
$endgroup$
– Nicky Hekster
Feb 16 '14 at 17:04












$begingroup$
Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
$endgroup$
– Omnomnomnom
Feb 16 '14 at 17:11






$begingroup$
Ah, I suppose I could have been more delicate there. I wanted to save OP the hunt for non-commuting matrices, which is particularly unpleasant if you don't know what to look for.
$endgroup$
– Omnomnomnom
Feb 16 '14 at 17:11





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