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When is the image of $\operatorname{Gal}(\bar K/K)$ open in $\operatorname{Aut}(V)$, where $V$ is the vector space coming from a $p$-adic Tate module?

Let $K$ be a finite extension of $\mathbb{Q}_p$ with ring of integers $A$. Let $F$ be a $p$-divisible group and $T$ be the Tate module. Consider the vector space $V=T \otimes_{\mathbb{Q}_p} C$, where $...
Learner's user avatar
  • 195
1 vote
0 answers
138 views

Syntomic f-cohomology for open varieties

Syntomic cohomology $H^{i+j}_{\mathrm{syn}}(X,n)$ of a proper variety $X$ with good reduction over a $p$-adic field $K$ is computed via a spectral sequence in terms of $H^i_{\mathrm{f}}(G_K;H^j_{\...
David Corwin's user avatar
  • 15.4k
3 votes
0 answers
347 views

Modern integral $p$-adic Hodge theory and modularity lifting and Fontaine-Mazur

As a follow-up to a comment on this answer, I'm wondering if there are expected to be applications of the new point of view on integral $p$-adic Hodge theory, à la Bhatt-Morrow-Scholze and others, to ...
David Corwin's user avatar
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2 votes
0 answers
161 views

What is the Galois representation structure of $B_{\text{cris}}^+/(t)$?

In $p$-adic Hodge theory, there is a nice exact sequence for quotients of $B_{\text{dr}}^+$. Denote by $t$ the typical uniformizer of $B_{\text{dr}}^+$ (the cyclotomic character), then there is a $G_{\...
kindasorta's user avatar
  • 2,907
5 votes
0 answers
556 views

Theorem 7.11 in Scholze's $p$-adic Hodge Theory

I was trying to understand the statement and proof of Theorem 7.11 in Scholze's paper "$p$-adic Hodge Theory for Rigid-Analytic Varieties". I'll reproduce part of the statement below: Let $...
Kush Singhal's user avatar
0 votes
0 answers
202 views

Kato's explicit reciprocity law paper

Does anyone have a copy of Kato's article Generalized explicit reciprocity laws in Advanced Studies in Contemp. Math which is used heavily in his paper constructing his eponymous Euler system? I used ...
xir's user avatar
  • 2,054
6 votes
0 answers
312 views

Geometry of syntomic cohomology

Deligne cohomology has a geometric interpretation. For example, $H^{2}_{\mathcal{D}}(X,\mathbb{Z}(1))$ is identified with the group $H^{1}(X,\mathcal{O}_{X}^{\ast})$ of isomorphism classes of line ...
Oli Gregory's user avatar
  • 1,404
2 votes
0 answers
194 views

Calculate $D_{\mathrm{cris}}(V)$ for a crystalline representation

$\newcommand{\cris}{\mathrm{cris}}$In my setting, $K/\mathbb Q_p$ is finite and unramified, and $V$ is a $2$-dimensional crystalline representation of $G_K$. Then we have $D_{\cris}(V)$, which is $2$-...
Richard's user avatar
  • 785
1 vote
0 answers
128 views

Centralizer of Frobenius on filtered $\phi$ module

Suppose $K$ is an unramified extension of $\mathbb Q_p$ of degree $m$, and $\sigma$ is the $p$ power frobenius on $K$. Suppose $V$ is a $2$ dimensional admissible filtered $\phi$ module over $K$. I ...
Richard's user avatar
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1 vote
0 answers
103 views

Is there a bound on the number of $p$-adic semisimple representations?

Faltings proved the following: Fix integers $w, d \geqslant 0$, and fix a number field $K$ and a finite set $S$ of primes of $\mathcal{O}_K$. There are, up to conjugation, only finitely many ...
Richard's user avatar
  • 785
2 votes
1 answer
243 views

$\pi$-adic Galois representations of attached to newforms at $p \nmid N$ are crystalline

Is [Scholl, Motives for modular forms, Theorem 1.2.4 (ii)] proven for any $p$ independent of the weight? Concretely, let $f$ be a normalized eigenform of weight $w$. Let $p$ be a prime not dividing ...
user avatar
3 votes
1 answer
513 views

p-adic period map in Lawrence and Venkatesh

In Lawrence and Venkatesh's paper on the Mordell conjecture, they prove that there are finitely many $K$-rational points on a hyperbolic curve $X$, where $K$ is a number field, by showing that there ...
kindasorta's user avatar
  • 2,907
6 votes
0 answers
630 views

On the Erratum to P. Scholze's "$p$-adic Hodge theory for rigid-analytic varieties"

I am trying to understand section (3) of the Erratum to P. Scholze's "$p$-adic Hodge theory for rigid-analytic varieties" in detail. In particular, there is the following sentence on page ...
user141099's user avatar
12 votes
2 answers
2k views

What is the Perrin-Riou logarithm (or regulator)?

Recently I've been rewatching some recordings of old talks on L-functions and explicit reciprocity laws (in particular, the series of talks by Loeffler and Zerbes given at this workshop at the CRM in ...
Anton Hilado's user avatar
  • 3,309
2 votes
1 answer
401 views

Crystalline when restricted to inertial subgroup

$\newcommand{\ur}{\mathrm{ur}}\newcommand{\cris}{\mathrm{cris}}$Let $K$ be a finite extension of $\mathbb{Q}_p$, $G_K=\operatorname{Gal}(\overline{K}/K)$ and $I_K \subset G_K$ its inertial subgroup. ...
Desunkid's user avatar
  • 247
1 vote
1 answer
243 views

Trianguline representation

I have a problem in understanding the concept of trianguline representation. Maybe someone can enlighten me. Let $K$ be a finite extension of $\mathbb{Q}_p$ and $V$ be a $p$-adic representation of $...
Konstantin's user avatar
10 votes
0 answers
2k views

Roadmap for p-adic Hodge theory

I'd like to be able to start studying p-adic Hodge theory and hope that by posing this question, I can be better prepared to work towards it. I ask for a roadmap because I understand that I have a lot ...
Krill's user avatar
  • 544
8 votes
1 answer
2k views

Some questions from the paper by Scholze-Weinstein

The following is from the paper by Scholze-Weinstein on moduli of $p$ divisible groups. My question is from a part of Lemma 4.1.7: If $R$ is a semiperfect ring, then the canonical map $W(R^{\flat}) \...
Ashutosh RC's user avatar
4 votes
1 answer
394 views

Reductive subgroups of $\mathrm{GL}_2$ over an algebraically closed field of characteristic zero

I am reading a very nice paper of Newton and Thorne, Symmetric power functoriality for holomorphic modular forms, and there is an argument concerning the (Zariski-closure of) image of certain $p$-adic ...
babu_babu's user avatar
  • 241
1 vote
1 answer
300 views

Exact sequence, de Rham representation

Let $k$ be a $p$-adic field and $G_k$ its absolute Galois group. Let $B_\text{dR}$ be the de Rham period ring with the usual filtration given by powers of $t$. For $i < j$ integers we have an exact ...
Konstantin's user avatar
12 votes
3 answers
3k views

Witt vectors, the cotangent complex, and a solid construction of $B_{dR}^+$

In a remarkable lecture delivered on October 29th: New Foundations for functional analysis, Dustin Clausen suggests at the 40 minute mark a remarkable new construction interpretation of Fontaine's ...
pupshaw's user avatar
  • 858
4 votes
0 answers
205 views

Grothendieck group of admissible $p$-adic representations

Let $K$ be a $p$-adic local field; $G = \mathop{\mathrm{Gal}}(\overline K | K)$; $\tau \in \{\text{HT}, \text{dR}, \text{crys}\}$, $B_\tau$ the corresponding period ring; $\mathop{\mathrm{Rep}}_{\...
Aoi Koshigaya's user avatar
8 votes
2 answers
631 views

Motivation of the construction of $p$-adic period rings

Let $B$ be either $B_{\text{dR}}$ or $B_{\text{crys}}$. For a $\mathbb{Q}_p$-representation $V$ of the absolute Galois group $\mathrm{Gal}(\overline{K}/K)$ of a $p$-adic field $K$ (a finite extension ...
User0829's user avatar
  • 1,428
3 votes
1 answer
390 views

The kernel from $A_\mathrm{inf}$ to $\mathcal{O}_{\mathbb{C}_K}$

I tried to understand this paper on page 31. Let $K$ be an finite extension of $\mathbb Q_p$ and $\overline{K}$ be its algebraic closure; $\mathcal{O}_{\overline{K}}$ is the ring of integers of $\...
CO2's user avatar
  • 275
4 votes
1 answer
347 views

A Tate-Sen theorem mod $p$

Let $p$ be a prime number, $G=\textrm{Gal}(\overline{\mathbb{Q}}_p/\mathbb{Q}_p)$, and $\chi:G\rightarrow\mathbb{Z}_p^\times$ the cyclotomic character. Let $\mathbb{C}_p$ denote the completion of the ...
jacob's user avatar
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3 votes
0 answers
336 views

A question on the Robba ring

Notation is as in the question: https://math.stackexchange.com/questions/4090045/some-questions-about-the-robba-ring. We define a new operator over the Robba ring as follows. Put $$c=\frac{pE(u)}{E(0)}...
lzhao's user avatar
  • 166
2 votes
1 answer
232 views

Local to global for semistable $G_{\mathbb{Q}_p}$-representations

Let $\rho_p:G_{\mathbb{Q}_p} \to \text{Gl}_n(\mathbb{Q}_p)$ be semistable representation. In local to global Galois representation, it was asked if one can find a geometric global Galois ...
curious math guy's user avatar
3 votes
1 answer
184 views

Restriction of $(\varphi, N)$-modules

For any $p$-dic field $K$, we have an equivalence of categories $$D_{st}:Rep_{\mathbb{Q}_p}^{st}(G_K)\rightarrow MF_K^{ad}(\varphi,N),\quad V\mapsto (B_{st}\otimes_{\mathbb{Q}_p} V)^{G_K}$$ with quasi-...
curious math guy's user avatar
7 votes
1 answer
422 views

Integral refinements of rigid cohomology

Disclaimer: I know absolutely nothing about p-adic cohomology, so it is possible that even the premises of this question are incorrect. But it turns out that I need to apply the theory of rigid ...
dhy's user avatar
  • 5,958
7 votes
1 answer
747 views

Finite non-empty coproduct in the absolute prismatic site

Let $(R/A)_\Delta$ be the prismatic site over $R$ relative to a prism $(A, I)$, then it is known that $(R/A)_\Delta$ admits finite non-empty coproduct, for instance, by Cor. 5.2 in Bhatt's lecture ...
Mayday's user avatar
  • 193
3 votes
1 answer
475 views

To identify $p$-adic Tate module $T_p(G)$ of $p$-divisible group $G$ in the category $\text{Rep}_{\mathbb{Q}_p}(G_{K_\infty})$

Let $k$ be a perfect field of characteristic $p>0$, $W=W(k)$ its ring of Witt vectors, $K_0=W(k)[\frac{1}{p}]$ and, $K/K_0$ be a totally ramified extension. Let $\pi \in K$ be an uniformizer. ...
MAS's user avatar
  • 930
10 votes
1 answer
1k views

How many untilts?

I read the following passage in Endomorphisms of power series fields and residue fields of Fargues-Fontaine curves by Kedlaya-Temkin: "One can construct many algebraic extensions of $\mathbb{Q}_p$...
Kostas Kartas's user avatar
11 votes
0 answers
390 views

Is there a period ring B_dif?

Let $K$ be a finite extension of $\mathbb{Q}_p$ and let $V$ be a p-adic representation of $\mathrm{Gal}(\overline{\mathbb{Q}}_p/K)$. Write $K_\infty=K(\mu_{p^{\infty}})$ for the cyclotomic extension ...
xlord's user avatar
  • 643
4 votes
0 answers
293 views

Galois representation with infinite image but finite image everywhere locally

Fix a prime $l$. Let $\phi:\mathrm{Gal}(\overline{\mathbb{Q}}/\mathbb{Q})\to GL_n(\mathbb{Q}_l)$ be a semisimple continuous representation. Assume $\phi$ has finite image when restricted to $\mathrm{...
user avatar
6 votes
1 answer
297 views

$B_{\mathrm{dR}}=B_{\mathrm{cris}}+{B_{\mathrm{dR}}^+}$?

$B_{\mathrm{cris}}\subseteq B_{\mathrm{dR}}$ and $B_{\mathrm{dR}}^+$ are well-known period rings in $p$-adic Hodge. I know $B_{\mathrm{dR}}=B_{\mathrm{dR}}^+[\frac{1}{t}]$ and $\frac{1}{t}\in B_{\...
user avatar
3 votes
1 answer
676 views

Would it be a little but good exercise to construct or find out Breuil modules?

My question is about p-adic Hodge-Tate theory and p-adic Galois representation. One of the important semi-linear object in p-adic Galois representation is the $\text{Breuil Module}$. There are ...
MAS's user avatar
  • 930
9 votes
1 answer
731 views

Tamagawa numbers

Let $K$ be a finite extension of $\mathbb{Q}_p$ with absolute Galois group $G_K$. Let $A$ be an abelian variety defined over $K$. The (geometric) Tamagawa number is defined as the order of the ...
Lukas's user avatar
  • 323
5 votes
1 answer
441 views

Motivation behind Fontaine's Theory

I am reading Fontaine's theory of $p$-adic Galois representations. But I am not able find the motivation behind it. Please let me know some good reference where I can study the motivation behind ...
user89236's user avatar
  • 101
4 votes
0 answers
234 views

Why does $\theta: \mathbb{B}^+_{dr} \rightarrow \mathbb{C}_p$ have no continuous or equivariant section?

Fix a $p$-adic field $K$ with perfect residue field $k.$ Let $\mathbb{C}_K$ be the completion of the algebraic closure of $K,$ and let $$R = \varprojlim \mathbb{C}_K/p,$$ where the transition maps in ...
DCM's user avatar
  • 217
15 votes
0 answers
592 views

Failure of local Fontaine Mazur

This question unfortunately has a very similar name to this one, but I what want to ask here is different. Let $K$ be a finite extension of $\mathbb{Q}_p$. It seems to be well known that the local ...
xlord's user avatar
  • 643
6 votes
2 answers
1k views

Topology on $p$-adic period rings in an article by Fontaine, part II

This is a follow-up to this question. See that question for background and relevant notation. In the answer to that question, it is claimed, if I understand the answer correctly, that a basis of ...
DCM's user avatar
  • 217
3 votes
1 answer
246 views

maximal unramified extension of Breuil ring in $A_{cris}$

Here is the notation. Let $k$ be a perfect field of characteristic $p$, $W=W(k)$ the ring of Witt vector and $\mathfrak{S}:=W[[u]]$, $\mathcal{O}_{\mathcal{E}}$ is the $p$-adic completion of $W[1/u]$ ...
quasi-mathematician's user avatar
4 votes
1 answer
888 views

Fontaine-Fargues curve and period rings and untilt

When I read the paper "THE FARGUES–FONTAINE CURVE AND DIAMONDS" of Matthew Morrow, I have a question on page 11. Question: The arthur said that the de Rham and crystalline period rings implicitly ...
user avatar
2 votes
1 answer
882 views

How to prove the p-adic Galois representations atteched to the Tate module of an abelian variety is de Rham directly?

Recently I read a thesis p-adic Galois representations and elliptic curves. Using Tate's curve, the author proved the p-adic Galois representations atteched to the Tate module of an elliptic curve is ...
user avatar
7 votes
2 answers
1k views

Classify 2-dim p-adic galois representations

Recently I have known how to classify 1-dim p adic Galois representations $\phi$. The p-adic Galois representations mean that a representation $G_K$ on a p-adic field $E$, where $K$ is also a p-adic ...
user avatar
4 votes
1 answer
350 views

Finite image but not crystalline

What is an example of a $p$-adic representation of the absolute Galois group of a $p$-adic field that has finite image on the inertia subgroup, but is not crystalline?
going_full_proper's user avatar
16 votes
3 answers
2k views

Tower of moduli spaces in Scholze's theory

My question is related to another one I read here in Overflow. I am reading Scholze's papers about moduli spaces of $p$-divisible groups and elliptic curves, and I am very interested in the formal ...
A. Walker's user avatar
  • 161
3 votes
0 answers
518 views

Condition on a Fontaine Laffaille module which prescribes the image of the associated Galois representation

The Setup: Let $m\geq 1$ be an integer, $\mathbb{F}$ be a finite field of characteristic $p$ and $W(\mathbb{F})$ the ring of Witt-vectors with residue field $\mathbb{F}$ and $\sigma:W(\mathbb{F})\...
user avatar
1 vote
0 answers
174 views

Reference to a particular result of Scholl and Faltings

Let $f=\sum_{n\geq 1} a_n q^n$ be a normalized eigenform which is supersingular and crystalline at a prime $p$ and let $V_f$ be the associated crystalline representation, then it follows from the work ...
user avatar
1 vote
0 answers
157 views

A family of crystalline representations

Let $K$ be a number field and let $v$ be a finite place of $K$. Further, let $g \geq 1$ be a positive integer. Consider the family $F(K,v,g)$ consisting of abelian varieties $A$ of dimension $2g$, ...
Stanley Yao Xiao's user avatar