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Tagged with congruences finite-fields
5 questions
7
votes
1
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Roots of a polynomial in a finite field related to Fermat's Last Theorem
In my class, we proved the following condition: define the polynomial $P_l(x)$ as
$$P_l(x) = \sum_{r=1}^{l-1}{\frac{1}{r}x^{l-1-r}}$$
Then if for all $a \in \mathbb{Z}/l\mathbb{Z}-\{0,1\},$ $P_l(x)$...
4
votes
2
answers
553
views
Non-torsion part of the abelianisation of congruence subgroups
I've posted this question on math.stackexchange, but haven't gotten any responses so I'm trying here instead.
Let $A = F_q[T]$ be the ring of polynomials in one variable with coefficients in a finite ...
4
votes
2
answers
616
views
Order of a matrix congruent to the identity modulo p
I couldn't find a demonstration of this theorem:
Given $A \in SO_2(\mathbb{Z}[{1 \over q_1},\dots,{1 \over q_k}])$
and $p$ prime $\notin \{q_1,\dots,q_k\}$
$\exists n \in \mathbb{N} : A^n=Id$ and $A\...
4
votes
0
answers
106
views
Differential duality: Triangular codes vs. VT codes / Single-substitution vs. Single-deletion
Here is the introduction to my problem:
Codes correcting single-deletion. Let $q$ and $n$ be non-negative integers, and let $\mathbf{x}= \left ( x_{1}, x_{2}, \ldots, x_{n} \right )\in\mathbb{Z}_{q}^{...
1
vote
2
answers
185
views
Number of solutions to $mx^2+ny^2 \equiv k\pmod{p}$
I need a reference for the result which gives the number of solutions to the congruence $mx^2+ny^2 \equiv k\pmod{p}$. This result seems to be something that would be discussed in Gauss' ...