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16 votes
2 answers
1k views

Representing $x^3-2$ as a sum of two squares

Prove that there exist infinitely many integers $x$ such that integer $P(x)=x^3-2$ is a sum of two squares of integers. Ideally, I am looking for a proof method that also applies for other $P(x)$, ...
Bogdan Grechuk's user avatar
2 votes
0 answers
96 views

Cryptography signature scheme based on hardness of finding points on varieties?

Related to this question Complexity of finding solutions of trapdoored polynomial. I am trying to build signature scheme based on hardness of finding points on varieties. Let $K$ be field and $M=K[x_1,...
joro's user avatar
  • 25.4k
16 votes
4 answers
1k views

Random Diophantine polynomials: Percent solvable?

Suppose one generates a random polynomial of degree $d$ with integer coefficients uniformly distributed within $[-c_\max,c_\max]$. For example, for $d=8$, $|c_\max|=100$, here is one random polynomial:...
Joseph O'Rourke's user avatar
7 votes
0 answers
533 views

$a^5+b^5=c^5+d^5$ and polynomial identities

No nontrivial integer solutions to $$ a^5+b^5=c^5+d^5 \qquad (1)$$ are known. (1) has infinitely many solutions in an extension of $\mathbb{Z}$ (root of $9-15x+37x^2 $ ) resulting from a genus 0 ...
joro's user avatar
  • 25.4k
6 votes
1 answer
1k views

Find all integer solutions to the following easy-looking Diophantine equations

In general, it is not clear What does it mean to solve an equation? in integers. In this question, let us assume that an equation $$ P(x_1,\dots,x_n)=0 $$ is solved if we have proved that its integer ...
Bogdan Grechuk's user avatar
2 votes
1 answer
360 views

Positive divisors of $P(x,n)=1+x+x^2+ \cdots + x^n$ that are congruent to $1$ modulo $x$

This is a follow-up question to Positive integer solutions to the diophantine equation $(xz+1)(yz+1)=z^4+z^3 +z^2 +z+1$ Let \begin{equation} P(x,n)= 1+x+x^2+ \cdots + x^n, \end{equation} \begin{...
ASP's user avatar
  • 319
2 votes
3 answers
568 views

Polynomial parametrization of the solutions to $yz=x^2+x\pm 1$

If a Diophantine equation has infinitely many integer solutions, how to describe them all? One standard approach is polynomial parametrization. For example, all integer solutions to the equation $$ yz=...
Bogdan Grechuk's user avatar