Let $Z_i(G)$ be the terms of the upper central series of $G$. Let $H trianglelefteq G$. Show $Z_i(G)H/H...
$begingroup$
Let $Z_0(G) = { 1 }$ and:
$$Z_{i + 1}(G)/Z_i(G) = Z(G/Z_i(G))$$
(as defined in dummit and foote).
I want to show that $Z_i(G)H/H subseteq Z_i(G/H)$.
I can see it's true for $i = 0$ and $i = 1$, but I'm stuck in the inductive case because I have to work with quotients of quotients (and not in the form $(G/H)/(K/H)$ so no 3rd isomorphism theorem).
In other words, I have an element $zH in Z_{i + 1}(G)H/H$.
I want to show that it is in $Z_{i + 1}(G/H)$, which is defined recursively as
$$Z_{i + 1}(G/H)/Z_i(G/H) = Z((G/H)/Z_i(G/H)).$$
group-theory nilpotent-groups
$endgroup$
add a comment |
$begingroup$
Let $Z_0(G) = { 1 }$ and:
$$Z_{i + 1}(G)/Z_i(G) = Z(G/Z_i(G))$$
(as defined in dummit and foote).
I want to show that $Z_i(G)H/H subseteq Z_i(G/H)$.
I can see it's true for $i = 0$ and $i = 1$, but I'm stuck in the inductive case because I have to work with quotients of quotients (and not in the form $(G/H)/(K/H)$ so no 3rd isomorphism theorem).
In other words, I have an element $zH in Z_{i + 1}(G)H/H$.
I want to show that it is in $Z_{i + 1}(G/H)$, which is defined recursively as
$$Z_{i + 1}(G/H)/Z_i(G/H) = Z((G/H)/Z_i(G/H)).$$
group-theory nilpotent-groups
$endgroup$
$begingroup$
Rewrite the recursive definition as $Z_{i+1}left(Gright) = left{g in G mid ghg^{-1}h^{-1} in Z_ileft(Gright) text{ for all } h in G right}$. Do you now see why each $Z_i$ is functorial wrt surjective homomorphisms (i.e., each surjective group homomorphism $f : G to H$ sends $Z_ileft(Gright)$ into $Z_ileft(Hright)$ for each $i$)?
$endgroup$
– darij grinberg
Dec 7 '18 at 2:44
add a comment |
$begingroup$
Let $Z_0(G) = { 1 }$ and:
$$Z_{i + 1}(G)/Z_i(G) = Z(G/Z_i(G))$$
(as defined in dummit and foote).
I want to show that $Z_i(G)H/H subseteq Z_i(G/H)$.
I can see it's true for $i = 0$ and $i = 1$, but I'm stuck in the inductive case because I have to work with quotients of quotients (and not in the form $(G/H)/(K/H)$ so no 3rd isomorphism theorem).
In other words, I have an element $zH in Z_{i + 1}(G)H/H$.
I want to show that it is in $Z_{i + 1}(G/H)$, which is defined recursively as
$$Z_{i + 1}(G/H)/Z_i(G/H) = Z((G/H)/Z_i(G/H)).$$
group-theory nilpotent-groups
$endgroup$
Let $Z_0(G) = { 1 }$ and:
$$Z_{i + 1}(G)/Z_i(G) = Z(G/Z_i(G))$$
(as defined in dummit and foote).
I want to show that $Z_i(G)H/H subseteq Z_i(G/H)$.
I can see it's true for $i = 0$ and $i = 1$, but I'm stuck in the inductive case because I have to work with quotients of quotients (and not in the form $(G/H)/(K/H)$ so no 3rd isomorphism theorem).
In other words, I have an element $zH in Z_{i + 1}(G)H/H$.
I want to show that it is in $Z_{i + 1}(G/H)$, which is defined recursively as
$$Z_{i + 1}(G/H)/Z_i(G/H) = Z((G/H)/Z_i(G/H)).$$
group-theory nilpotent-groups
group-theory nilpotent-groups
edited Dec 7 '18 at 2:27
darij grinberg
10.5k33062
10.5k33062
asked Dec 7 '18 at 2:25
RaekyeRaekye
24539
24539
$begingroup$
Rewrite the recursive definition as $Z_{i+1}left(Gright) = left{g in G mid ghg^{-1}h^{-1} in Z_ileft(Gright) text{ for all } h in G right}$. Do you now see why each $Z_i$ is functorial wrt surjective homomorphisms (i.e., each surjective group homomorphism $f : G to H$ sends $Z_ileft(Gright)$ into $Z_ileft(Hright)$ for each $i$)?
$endgroup$
– darij grinberg
Dec 7 '18 at 2:44
add a comment |
$begingroup$
Rewrite the recursive definition as $Z_{i+1}left(Gright) = left{g in G mid ghg^{-1}h^{-1} in Z_ileft(Gright) text{ for all } h in G right}$. Do you now see why each $Z_i$ is functorial wrt surjective homomorphisms (i.e., each surjective group homomorphism $f : G to H$ sends $Z_ileft(Gright)$ into $Z_ileft(Hright)$ for each $i$)?
$endgroup$
– darij grinberg
Dec 7 '18 at 2:44
$begingroup$
Rewrite the recursive definition as $Z_{i+1}left(Gright) = left{g in G mid ghg^{-1}h^{-1} in Z_ileft(Gright) text{ for all } h in G right}$. Do you now see why each $Z_i$ is functorial wrt surjective homomorphisms (i.e., each surjective group homomorphism $f : G to H$ sends $Z_ileft(Gright)$ into $Z_ileft(Hright)$ for each $i$)?
$endgroup$
– darij grinberg
Dec 7 '18 at 2:44
$begingroup$
Rewrite the recursive definition as $Z_{i+1}left(Gright) = left{g in G mid ghg^{-1}h^{-1} in Z_ileft(Gright) text{ for all } h in G right}$. Do you now see why each $Z_i$ is functorial wrt surjective homomorphisms (i.e., each surjective group homomorphism $f : G to H$ sends $Z_ileft(Gright)$ into $Z_ileft(Hright)$ for each $i$)?
$endgroup$
– darij grinberg
Dec 7 '18 at 2:44
add a comment |
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$begingroup$
Rewrite the recursive definition as $Z_{i+1}left(Gright) = left{g in G mid ghg^{-1}h^{-1} in Z_ileft(Gright) text{ for all } h in G right}$. Do you now see why each $Z_i$ is functorial wrt surjective homomorphisms (i.e., each surjective group homomorphism $f : G to H$ sends $Z_ileft(Gright)$ into $Z_ileft(Hright)$ for each $i$)?
$endgroup$
– darij grinberg
Dec 7 '18 at 2:44