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8 votes
1 answer
366 views

Why do we have fewer distinct Gauss sums over a field of characteristic $2$?

Let $p$ be a prime number and $q$ be a power of $p$. Fix a non-trivial additive character $\psi\colon \mathbb{F}_q\to \mathbb{C}^\times$ and, for each non-trivial multiplicative character $\chi\colon \...
0 votes
0 answers
107 views

Cubic monic polynomial over z_p

Let $$ f_{a}(x)=x^3+(u-2-a)x^2+ax+1, $$ where $u\in\mathbb{Z}_p^*$ is fixed. Let $S$ be the set consisting of all $a\in\mathbb{Z}_p$ such that $f_{a}(x)$ factor linearly. Then what is the cardinality ...
1 vote
1 answer
468 views

Artin's conjecture for polynomials and rational functions over finite fields

Artin's conjecture on primitive roots over the integers states that a given integer $0\ne h\in \mathbb{Z}$ that is neither a square number nor $-1$ is a primitive root modulo infinitely many primes $p$...
14 votes
1 answer
285 views

Lower bounds for class number of function fields with fixed $q$, growing $g$

Let $X$ be a smooth project curve of genus $g$ over the finite field with $q$ elements. Let $h$ be $\# \mathrm{Pic}^0(X)(\mathbb{F}_q)$. Weil showed that $h \geq (\sqrt{q}-1)^{2g}$. Lachaud and Martin-...
4 votes
0 answers
134 views

$\delta$-equidistributed polynomials over finite fields

I'm trying to show that a polynomial over finite (prime) field is "close enough" to being equidistributed over its range. A polynomial $p(\cdot)$ from $\mathbb{F}^n$ to $\mathbb{F}$ is $\...
2 votes
1 answer
600 views

Density of rational points over finite fields, an estimate of Lang-Weil constant

Let $X\hookrightarrow\mathbb P^n_{\mathbb F_q}$ be a geometrically integral hypersurface over the finite field $\mathbb F_q$ of degree $\delta$. In order to estimate the number of its rational points, ...
2 votes
0 answers
87 views

Variation of Gauss/Jacobi sums on a variety

Let $V \subset \mathbb P^n$ be a nice (smooth, projective?) variety over a finite field $\mathbb F_q$. Let $\chi_0,\chi_1,\dots,\chi_{n}: \mathbb F_q^\times \to \mathbb Q(\mu_{q-1})$ be multiplicative ...
2 votes
1 answer
277 views

Is there an analogue of the Balazard-Saias-Yor criterion for the Riemann Hypothesis for finite fields?

The Balazard-Saias-Yor criterion for the Riemann Hypothesis states that the latter is equivalent to the statement that $$\int_{\Re(s)=1/2} \frac{\log|\zeta(s)|}{|s^2|}|ds|=0$$ where $\zeta$ denotes ...
2 votes
0 answers
249 views

An exponential sum like the Kloosterman sums

I encounter a tricky sum like the Kloosterman sum $${\sum_{x \mod P}}^\ast e\left(\frac{ax+\overline{x}}{P}+\frac{lx^2}{P^2}\right),$$ where $l$ is a positive integer co-prime with $P$ and here $P$ ...
8 votes
2 answers
564 views

Distribution of primitive roots, as p varies

For a prime number $p$, let $\Phi(p)$ be the subset of $\{ 1, 2, \ldots, p-1 \}$ consisting of primitive roots modulo $p$. (Thus $\# \Phi(p) = \phi(p-1)$, where $\phi$ denotes the totient.) I am ...
5 votes
1 answer
328 views

Does a Kloosterman sum composed with a rational function exhibit square root cancellation?

Denote the classical Kloosterman and Salié sums, respectively, as $KL(a,b) = \sum_{r \in F_*} e(ar+\frac{b}{r})$ and $SL(a,b) =\sum_{r \in F_*} \chi(r) e(ar+\frac{b}{r})$, where $\chi(\cdot)$ is the ...
7 votes
3 answers
911 views

Does the equation $x^2+x=a$ have an integer solution?

I am writing a paper on the topological structure of the Golomb space (defined here) and arrived to the following question: Question 1. Is it true that for a number $a\in\mathbb N$ the equation $x^2+...
2 votes
1 answer
260 views

Fixed points of $g^x$ (modulo a prime)

In an explicit construction in combinatorics I need to study the following problem: assume we pick a odd prime number $p$, a generator $g$ of the multiplicative group $(Z/pZ)^{\ast}$. Question 1: ...
4 votes
1 answer
307 views

When the Kloosterman sum is an integer?

Let $q$ be a power of prime $p$ and $\zeta_p$ be the complex $p$ th root of unity. We denote by $\mathbb{F}_q$ the finite field of $q$ elements and by $Tr$ the absolute trace function $\mathbb{F}_q\...