Questions tagged [p-adic-analysis]
p-adic analysis is a branch of number theory that deals with the mathematical analysis of functions of p-adic numbers.
315 questions
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Irreducibility of a degree-$27$ polynomial through Newton polygon or residual reduction
Let $K=\mathbb{Q}_3(t)$ be the finite extension of the $3$-adic number field $\mathbb{Q}_3$, where $t=3^{1/13}$. I want to know if the polynomial $$f(x)=(x^9-t^2)^3-3^4x+3^3t^5 \in K[x]$$ is ...
3
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83
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Non-solvable subgroups of the first congruence subgroup of two-dimensional special linear group over $\mathbb{F}_{p}[[T]]$
Let $p$ be an odd prime and $\mathbb{Z}_{p}$ be the ring of $p$-adic integers. Let $\mathbb{F}_{p}$ be the finite field of order $p$ and let $\mathbb{F}_{p}[[T]]$ be the ring of formal power series ...
2
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147
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Find a ring R such that Spec R is homeomorphic to Spa(Z,Z)
I'm following Scholze-Weinstein's Berkeley notes (https://www.math.uni-bonn.de/people/scholze/Berkeley.pdf). And there is a theorem by Huber (Thm 2.3.3) in the notes that says the adic spectrum $\...
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48
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Pointwise bounded subvariety in a rigid tube
I encountered the following question when studying the cohomology of a char p variety, which is really outside of my area of expertise.
Notation: $\mathbb{F}=\mathbb{F}_p$ bar, $W$ its Witt ring, $K=W[...
5
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249
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Non-Archimedean disks
Let $K$ be a field complete with respect to a non-Archimedean absolute value $|\cdot|$. To develop analysis in $K$, we need the notion of a disk in $K$. There is nothing mysterious at first glance: ...
14
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1
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480
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Explicit witness to spherical incompleteness of $\mathbb{C}_p$
A nonarchimedean valued field $K$ is said to be spherically complete if, for any nested sequence $B_1 \supseteq B_2 \supseteq \dots$ of balls in $K$, the intersection $\bigcap_{i = 1}^\infty B_i$ is ...
2
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81
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Orthogonalization of quadratic forms over a $p$-adic Banach space
Let $X$ be an arbitrary set. Let $H = c_0(X, \mathbb{Q}_p)$ be the $p$-adic Banach space with sup norm. Let $\langle \cdot, \cdot \rangle$ be a symmetric, nondegenerate $\mathbb{Q}_p$-bilinear form on ...
4
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184
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Radius of convergence of solution to p-adic differential equation
I am working on a problem that seems to reduce to determining (to certain precision) the radius of convergence of a particular solution of a p-adic differential equation.
In particular, we have $f(x) =...
12
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If a $p$-adic power series vanishes at $\zeta_{p^n}^a-1$ for all $n,a$, is it divisible by $\log(1+T)$?
Let $p$ be a prime number, and let $H(\mathbb{C}_p)$ denote the ring of power series $f(T)\in \mathbb{C}_p[[T]]$ such that $f(T)$ converges in an open ball of radius $1$ about $0$. n.b. that this is ...
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111
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Is the NH hash family $\varepsilon$-AXU?
As context, I'll start with summarizing and simplifying the section of "UMAC: Fast and Secure Message Authentication", by Black et al.(https://www.cs.ucdavis.edu/~rogaway/papers/umac-full....
2
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99
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Restriction of a Schwartz function to Bruhat open cell over p-adic field
Let $G=GL_n(F)$ over a p-adic field $F$, use $\mathcal{S}(G)$ to denote the compactly supported locally constant functions on $G$. Let $\Omega_n:=N_nA_n\omega_n N_n$ be the open dense Bruhat cell of $...
4
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algebraic fundamental group of Raynaud generic fiber
Let $k$ be a perfect field of characteristic $p$. Let $X$ be a quasi-projective smooth variety over the Witt ring $W=W(k)$ ($K=\mathrm{Frac}(W)$). Let $\mathcal X$ be the $p$-adic formal completion of ...
2
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Is the torsion points $F[p^{\infty}]$ of a formal group law Zariski dense in $\mathfrak{m}_{\mathbb{C}_p}^d$?
Let $F$ be a $d$-dimensional formal group of finite height over the ring of $p$-adic integers $\mathbb{Z}_p$. Let $\mathfrak{m}_{\mathbb{C}_p}$ be the unit disk in $\mathbb{C}_p$. Since $F$ the formal ...
7
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A constant appearing in Dwork's work on the Bessel equation
In Dwork's paper "Bessel functions as $p$-adic functions of the argument", a certain constant $\gamma$ arises as a matrix entry in his calculations of a Frobenius structure that he ...
7
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455
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Does $\operatorname{GL}_2(\mathbb Z_p)$ have any open solvable subgroup?
Let $\mathbb{Z}_p$ denote the $p$-adic integers. Does $\operatorname{GL}_2(\mathbb Z_p)$ have an open solvable subgroup $H $? By solvable I mean that there exist a chain of subgroups
$$1=G_0\lhd G_1 \...
1
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1
answer
208
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Action of profinite powers of an integer matrix in $\operatorname{SL}(2,\mathbb{Z}_p)$ on $\mathbb{Z}^2$
$\DeclareMathOperator\SL{SL}\DeclareMathOperator\tr{tr}$Let $A\in \SL(2,\mathbb{Z})$. Inside $\SL(2,\mathbb{Z}_p)$, we can consider profinite powers $A^r$, where $r\in\widehat{\mathbb{Z}}$. For ...
7
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331
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Moral/geometric interpretation of Tate's ramification calculations
I've been reading the proof of Ax–Sen–Tate from Caruso - An introduction to p-adic period rings; it says that $\mathbb{C}_p^G = \mathbb{Q}_p$.
The proof contains subtle computations which I want to ...
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1
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134
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Localization of almost finite torsion $\mathcal{O}_C$-algebras
Let $C$ be the completion of an algebraic closure of $\mathbb{Q}_p$, and let $\mathcal{O}_C$ be its ring of integral elements. Let $A$ be an $\mathcal{O}_C$-algebra that is torsion and almost ...
0
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1
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235
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How to efficiently replace the Paterson-Stockmeyer algorithm and reduce non-scalar multiplications
Paterson-Stockmeyer algorithm
If we need to compute a high-degree polynomial expression, such as:
$$
P(y) = \sum_{k=0}^{B} a_k y^k
$$
the Paterson-Stockmeyer algorithm can process the powers in ...
2
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1
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116
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Zero of power series and Newton polygon in non-archimedean complete algebraically closed fields
In Gouvea book $p$-adic numbers, on can find this corollary (7.4.11)
Let $f(X) = 1+a_1X+a_2X^2+a_3X^3+\cdots$ be a power series which converges on the closed ball of radius $c = p^m$. Let $m_1, m_2, \...
1
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1
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303
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Can a p-adic ball cover a p-adic ball?
Are there a polynomials $f_1,...f_n \in \mathbb{Z}_p[x_1,...x_n]$ with there coeficients $p$-adic integers s.t.
A map $F:\mathbb{Z}_p^n\rightarrow \mathbb{Z}_p^n$ defined by $f_1,...f_n$
satisfy the ...
3
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1
answer
332
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The simply connectedness of $\mathbb{A}^n_{\mathbb{Q}_p}$
My question is how to prove the affine $n$-space over $p$-adic number $\mathbb{Q}_p$ is simply connected.
To be precise,
Let $X$ be $p$-adically analytic manifold, $f:X\rightarrow \mathbb{A}^n_{\...
9
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1
answer
307
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$p$-adic analytic pro-$p$ group satisfies a pro-$p$ identity?
Let $p$ be a prime. Let $w$ be an element of a free pro-$p$ group $F_r$ of finite rank $r\geq 2$. Then we say that a pro-$p$ group $G$ satisfies the pro-$p$ identity
$w$ if for every homomorphism $ f:...
2
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1
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295
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A question on signed Stirling numbers of the first kind
Let $(x)_0=1$ and $(x)_n=x(x-1)\cdots(x-n+1)$ for $n=1,2,3,\ldots$. The signed Stirling numbers of the first kind, $s(n,k)$ with $n\ge k\ge0$, are defined by
$$(x)_n=\sum_{k=0}^ns(n,k)x^k.$$
Question. ...
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132
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Is the Galois closure of a $p$-adic Lie group extension also a $p$-adic Lie group extension?
Let $p$ be a prime. Let $K$ be a number field and $L/K$ be an infinite extension which is not necessarily Galois. Suppose that the automorphism group $\text{Aut}(L/K)$ of $L/K$ is $p$-adic analytic, i....
2
votes
1
answer
172
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Extending $p$-adic smooth and locally constant functions
Let $G$ be $p$-adic group and let $G \rightarrow GL(V)$ be a representation. For example, $V$ is a quadratic $\mathbb{Q}_p$-space and $G$ is the associated orthogonal group.
Take a point $v \in V$, ...
11
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1
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477
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Closed image of curves under $p$-adic logarithm, Coleman integrals and Bogomolov
Disclaimer: my knowledge of $p$-adic analysis/geometry is minimal.
Consider a smooth, complete curve $C$ of genus $g$ over $\mathbb{C}_{p}$, denote by $J$ its Jacobian and consider the embedding $C\...
3
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0
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93
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What circumstances guarantee a p-adic affine conjugacy map will be a rational function?
Let $\Bbb Q_p$ be a p-adic field and let any element $x$ of $\Bbb Q_p$ be associated with a unique element of $\Bbb Z_p$ via the quotient / equivalence relation $\forall n\in\Bbb Z:p^nx\sim x$
Then in ...
0
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0
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117
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Can every $\ast$-algebra be represented in this space of matrices?
Let $k$ be a field with characteristic $0$. For every set $X$, let $\mathcal{B}(X)$ be the set of (possibly infinite) matrices $T = (T_{x,y})_{x,y \in X}$ with coefficients in $k$ such that in each ...
4
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1
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228
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Maximum modulus principle over the $p$-adic integers
Consider $\mathbb{Z}_p$ the $p$-adic integers. Let $f\in\mathbb{Z}_p[x]$ be an arbitrary polynomial in one variable. Write $f(x) = \sum_{k}a_kx^k$. Is it true that $\|f\|:= \max_k |a_k|_p = \sup_{t \...
0
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0
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117
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Exact approximation in $p$ adic
Given a non increasing function $\psi$ the $\psi$ approximable points in $\mathbb{R}^n$ is defined as
$W(\psi)=\{x\in\mathbb{R}^n:|qx-p|<\psi(q)\}$ for infinitely many $(q,p)\in \mathbb{Z}^m\times\...
4
votes
1
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421
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Compactification of rigid-analytic varieties
Is it true that any separated quasi-compact rigid-analytic variety embeds into a proper one?
For my purpose, the base field is a $p$-adic number field.
I have seen Huber's universal compactification ...
3
votes
2
answers
333
views
Examples of non-splittable norms
Let $K$ be a complete non-archimedean field. A norm on a finite dimensional vector space $V$
is a function $| \cdot | : V \to \mathbf{R}$ which satisfies the usual norm properties (with the non-...
4
votes
1
answer
311
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Irreducible components of rigid varieties
I'm reading IRREDUCIBLE COMPONENTS OF RIGID SPACES (by Conrad). In this paper he defines the irreducible component of a rigid variety $X$ to be reduced image of a connected component of $\tilde X$ (...
2
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1
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237
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Integral over the space of $p$-adic matrices
$\DeclareMathOperator\Mat{Mat}$Let $\mathbb{F}$ be a non-Archimedean local field. Let $\mathcal{O}$ be its ring of integers with a uniformizer $\pi$. Let $|\cdot|\colon \mathbb{F}\to \mathbb{R}$ be ...
4
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0
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140
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Projective reduction of image of power series is algebraic?
Let $K$ be a non-archimedean field with closed unit disk $\mathcal{O}\subset K$, open unit disk $\mathfrak{m}\subset \mathcal{O}$ and residue field $k = \mathcal{O}/\mathfrak{m}$.
Examples to keep in ...
5
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238
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Bezout-type theorem for $p$-adic analytic plane curves
Let $p$ be a prime, and let $f,g \in \mathbb{Z}_p[[x,y]]$ be power series convergent on all of $\mathbb{Z}_p$. Suppose that the intersection of the analytic plane curves cut out by $f$ and $g$ is ...
3
votes
1
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221
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Approximating $p$-adic power series by polynomials
Let $p$ be a prime, and let $f \in \mathbb{Z}_p[[x_1,\dots,x_d]]$ be a power series convergent on all of $\mathbb{Z}_p^d$. We make the following definition concerning the approximation of $f$ by ...
2
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0
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215
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p-adic Banach space and complete tensor product
Let $p$ be a prime and $\mathbb{C}_{p}$ the completion of the algebraic closure of the $p$-adic number field $\mathbb{Q}_p$.
Let $M$ be a $\mathbb{Q}_p$-Banach space.
We denote by $M\mathbin{\widehat{\...
1
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1
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501
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Does $\sum_{n \geq 0} a_n x^n=\sum_{n \geq 0} b_nx^n$ imply $a_n=b_n$ for vector-tuple power series?
My reference is Infinite series in p-adic fields by Keith Conrad.
Corollary 5.6. If $f(x)=\sum_{n≥0} a_nx^n$ has a positive radius of convergence in the $p$-adic field $\mathbb Q_p$ then $f$ is ...
4
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1
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255
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Partition of unity for analytic manifolds over non-Archimedean local fields
I am looking for a reference to the following fact which, I hope, is correct.
Let $X$ be a compact analytic manifold over a non-Archimedean local field. Let
$X=\cup_\alpha U_\alpha$ be a finite open ...
1
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0
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98
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The bound for zeros of the composition of polynomials and analytic functions
Suppose $K$ is a number field, and $A\in M_n(K)$. $v$ is a place of $K$, and $f_1,\cdots,f_n$ are analytic functions (one variable) on $m_v\mathcal O_{K,v}$, satisfying: $\frac{\mathrm d \bf {f}}{\...
2
votes
1
answer
197
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How to get a ball in the nonvanishing locus of a polynomial in $\mathbb Z_p[x_1,\cdots,x_n]$ canonically?
Suppose $f\in \mathbb Z_p[x_1,\cdots,x_n]$, and consider $D(f):=\{(𝑥_1,…,𝑥_𝑛)∈ℤ^𝑛_𝑝:𝑓(𝑥_1,…,𝑥_𝑛)≠0\}\subset \mathbb Z_p^n$. How to calculate a radius $r$ from the datum of $f$ such that $D(f)$...
4
votes
1
answer
242
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Meaning of dagger cohomology $H^{1 \dagger}(G^\dagger)$ in "Frobenius and Monodromy Operators" by Coleman and Iovita
Let $G$ be an abelian variety with good reduction over a finite extension $K$ of $\mathbb{Q}_p$. In equation (2.4) on page 179 of my edition of "The Frobenius and monodromy operators for curves ...
3
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0
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225
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Wondering if Monsky-Washnitzer ever published a result claimed to be forthcoming in a later paper
At the very end of the paper Formal Cohomology I by Monsky and Washnitzer, they write the following:
"In some sense, the operator $\psi$ applied to a power series gives it "better
growth ...
4
votes
0
answers
267
views
Notion of connected components for $\mathbb{Q}_p$-points of algebraic variety
Is there an interesting notion of connected components for the $\mathbb{Q}_p$-points of an algebraic variety over $\mathbb{Q}_p$? By "interesting" I mean a notion satisfying the following. ...
2
votes
0
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165
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$p$-adic Banach group algebra
Let $G$ be a discrete group. Consider the Banach $\mathbb{Z}_p$-algebra: $$c_0(G, \mathbb{Z}_p) = \{ F : G \to \mathbb{Z}_p \mid \lim_{g \to \infty} |F(g)|_p = 0 \}$$ with the product given by the ...
1
vote
1
answer
308
views
Formal series which are always zero
Let $(k, |\cdot|)$ be a complete field with a non-Archimedean norm, not necessarily algebraically closed. Define the Tate algebra as follows:
\begin{align*}
k \langle T_1, \dots, T_n \rangle = \{ \...
0
votes
0
answers
98
views
Space of non-archimedean characters is nonempty
Let $k$ be an algebraically closed complete non-archimedean field. Let $\mathcal{O}_k$ be its ring of integers. Suppose that $A$ is a $k$-Banach algebra, and $B$ is its closed unitary ball. Note that $...
2
votes
1
answer
295
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Twist of the Tate Curve
Suppose we have an elliptic curve $E$ over $K$, an $l$-adic field. Say that $|j(E)|>1$ where $|.|$ is the $l$-adic valuation. By the theory of the Tate curve $E$ is isomorphic over $L$ to a Tate ...