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3 votes
1 answer
272 views

Does there exist a polynomial that extracts the highest digit of an integer in base p?

Given an odd prime $p$, a positive integer $1 \lt n$, and an integer $x \in \mathbb{Z}/p^n\mathbb{Z}$, does there exist an an integer-coefficient polynomial that extracts the highest digit of $x$? The ...
fofo's user avatar
  • 31
0 votes
1 answer
607 views

Method to solve modular quadratic polynomial [duplicate]

If $q$ is a prime what is the best method to compute roots of a quadratic polynomial $f(x)\equiv0\bmod q^2$ which is of form $x^2+bx+c\equiv0\bmod q^2$ where $b^2-4c\equiv0\bmod q$ and $gcd(b,q)=1$ ...
Turbo's user avatar
  • 13.9k
18 votes
1 answer
714 views

Is the p-adic density of the image of a polynomial always rational?

This question was previously posted here on MSE. Let $P(x)$ be a polynomial with integer coefficients, and let $p$ be a prime number. For $n\in\mathbb N$, let $I_n$ be the number of integers $i\in\{1,\...
Riemann's user avatar
  • 654
0 votes
1 answer
269 views

If two monic polynomials of $\mathbb{Z}_p[X]$ (p-adic integer coefficient) are relatively prime modulo p, then do they generate $\mathbb{Z}_p[X]$?

I'm currently reading a paper of Rene Schoof, and I got stuck in a line. And I'm trying to check the above sentence. Although that seems to be elementary, I hope someone can give me a counterexample ...
gualterio's user avatar
  • 1,013
11 votes
2 answers
813 views

lowest degree of polynomial that removes the first digit of an integer in base p

Let $p$ be an odd prime and $n \geq 2$. (1) Does there exist an integer-coefficient polynomial $f$ such that $f(x) = x - (x \bmod p)$ for all $x \in \mathbb{Z}/p^n \mathbb{Z}$? The polynomial ...
hao chen's user avatar
3 votes
0 answers
119 views

Does anyone know anything about the 2-valuation of the discriminant of a polynomial?

Take a random polynomial $f$ with integer coefficients (e.g., choose coefficients between $1$ to $B$ of a fixed degree $n$ and let $B$ tend to $\infty$). Using computer we noted that the 2-valuation ...
Lior Bary-Soroker's user avatar
3 votes
0 answers
174 views

Carlitz factorials and Euler-like series

Let $q$ be a power of a prime $p$. For every $i\in\mathbb N$, one denotes $D_i=\prod_{\substack{h\in\mathbb F_q[T]\text{ monic}\\\deg h=i}}\limits h$. For $n\in\mathbb N$, write $$n=n_0+n_1q+\cdots+...
joaopa's user avatar
  • 3,998
6 votes
2 answers
2k views

Polynomial reducible modulo every integer

Hi, let $f\in\mathbb{Z}[X]$ be a monic polynomial. Assume that the reduction of $f$ modulo $m $ is reducible for all integers $m\geq 2$. Q1: Is $f$ reducible in $\mathbb{Z}[X]$ ? I've thought ...
GreginGre's user avatar