Skip to main content
formatting, added tag, fixed English
Source Link
YCor
  • 63.9k
  • 5
  • 187
  • 286

formal Formal group as a limit of its finite subgroupsubgroups

I'm reading Manin's article on formal groups and I have a problem with lemmaLemma 1.1. consider kConsider $k$ a prefect ring of characteristic p$p$ and (A,m,k)$(A,m,k)$ a noetherian complete local ring of the same characteristic such that $X=spf\, A$$X=\operatorname{spf} A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

defineDefine $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}$$$$\{x^{p^n}|x\in m\}.$$ (Manin useuses the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ is generated by these elements.) heHe proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and, if not, why A$A$ and $\varprojlim \frac{A}{m^{(p^n)}}$ are equalcan be identified as topological rings?

formal group as a limit of its finite subgroup

I'm reading Manin's article on formal groups and I have a problem with lemma 1.1. consider k a prefect ring of characteristic p and (A,m,k) a noetherian complete local ring of the same characteristic such that $X=spf\, A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

define $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}$$ (Manin use the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ generated by these elements.) he proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and if not why A and $\varprojlim \frac{A}{m^{(p^n)}}$ are equal as topological rings?

Formal group as a limit of its finite subgroups

I'm reading Manin's article on formal groups and I have a problem with Lemma 1.1. Consider $k$ a prefect ring of characteristic $p$ and $(A,m,k)$ a noetherian complete local ring of the same characteristic such that $X=\operatorname{spf} A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

Define $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}.$$ (Manin uses the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ is generated by these elements.) He proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and, if not, why $A$ and $\varprojlim \frac{A}{m^{(p^n)}}$ can be identified as topological rings?

deleted 47 characters in body
Source Link
ali
  • 1.1k
  • 7
  • 16

I'm reading Manin's article on formal groups and I have a problem with lemma 1.1. consider k a prefect ring of characteristic p and (A,m,k) a noetherian complete local ring of the same characteristic such that $X=spf\, A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

define $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}$$ (Manin use the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ generated by these elements.) he proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and if not why $\frac{A}{m^{(p^n)}}$ is finite over k and why A and $\varprojlim \frac{A}{m^{(p^n)}}$ are equal as topological rings?

I'm reading Manin's article on formal groups and I have a problem with lemma 1.1. consider k a prefect ring of characteristic p and (A,m,k) a noetherian complete local ring of the same characteristic such that $X=spf\, A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

define $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}$$ (Manin use the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ generated by these elements.) he proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and if not why $\frac{A}{m^{(p^n)}}$ is finite over k and why A and $\varprojlim \frac{A}{m^{(p^n)}}$ are equal as topological rings?

I'm reading Manin's article on formal groups and I have a problem with lemma 1.1. consider k a prefect ring of characteristic p and (A,m,k) a noetherian complete local ring of the same characteristic such that $X=spf\, A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

define $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}$$ (Manin use the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ generated by these elements.) he proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and if not why A and $\varprojlim \frac{A}{m^{(p^n)}}$ are equal as topological rings?

Source Link
ali
  • 1.1k
  • 7
  • 16

formal group as a limit of its finite subgroup

I'm reading Manin's article on formal groups and I have a problem with lemma 1.1. consider k a prefect ring of characteristic p and (A,m,k) a noetherian complete local ring of the same characteristic such that $X=spf\, A$ is a formal group. Manin wants to prove $X$ is a direct limit of finite group schemes over $k$.

define $m^{(p^n)}$ as the ideal generated by $$\{x^{p^n}|x\in m\}$$ (Manin use the notation $m^{p^n}$ but I don't understand why $m^{p^n}$ generated by these elements.) he proves that $\frac{A}{m^{(p^n)}}$ are Hopf algebras and because $A$ is complete we have $A=\varprojlim \frac{A}{m^{(p^n)}}$ as rings.

I don't understand if $m^{(p^n)}$ is really equal to $m^{p^n}$ and if not why $\frac{A}{m^{(p^n)}}$ is finite over k and why A and $\varprojlim \frac{A}{m^{(p^n)}}$ are equal as topological rings?