Skip to main content

All Questions

Filter by
Sorted by
Tagged with
20 votes
2 answers
2k views

On a result attributed to W. Ljunggren and T. Nagell

I've read in a number of places that, building on previous work of T. Nagell, W. Ljunggren proved in 1 that the Diophantine equation $$\frac{x^{n}-1}{x-1} = y^{2}$$ doesn't admit solutions in ...
José Hdz. Stgo.'s user avatar
38 votes
5 answers
10k views

Are nontrivial integer solutions known for $x^3+y^3+z^3=3$?

The Diophantine equation $$x^3+y^3+z^3=3$$ has four easy integer solutions: $(1,1,1)$ and the three permutations of $(4,4,-5)$. Elsenhans and Jahnel wrote in 2007 that these were all the solutions ...
András Salamon's user avatar
30 votes
9 answers
10k views

Diophantine equation with no integer solutions, but with solutions modulo every integer

It's probably common knowledge that there are Diophantine equations which do not admit any solutions in the integers, but which admit solutions modulo $n$ for every $n$. This fact is stated, for ...
Faisal's user avatar
  • 10.3k
13 votes
1 answer
760 views

Infinitely many integer solutions to $X^4+Y^4-18Z^4= -16$

We found infinitely many integer solutions to $$X^4+Y^4-18Z^4= -16 \qquad (1)$$. The interesting part in this diophantine equation is the sum of the reciprocals of the degrees is $3/4 < 1$, which ...
joro's user avatar
  • 25.4k
10 votes
5 answers
771 views

Reference request: Diophantine equations

I am looking for a textbook, or preferably lectures, on the subject of Diophantine equations. I am familiar with the basic principles of modular arithmetic, conics and the Hasse Principle, and the ...
Thomas's user avatar
  • 2,811
9 votes
1 answer
682 views

On the exact reference of a cute Diophantine problem

The problem asks to prove that the Diophantine equation $x^{3}+y^{3} = (x+y)^{2}+(xy)^{2}$ does not have any solutions in natural numbers $x, y$. I believe that this problem appeared in the section ...
José Hdz. Stgo.'s user avatar
9 votes
2 answers
683 views

The Theory of Transfinite Diophantine Equations [closed]

The theory of Diophantine equations is one of the main stream research areas in number theory. There are many known results and unknown conjectures about the existence of non-trivial solutions for ...
user avatar
6 votes
2 answers
713 views

Origin and variations of problem on $4xy-x-y$ being square

One of the forms in which the Diophantine equation in question can be found in the literature is this: Solve the equation \begin{eqnarray}z^{2} = 4xy-x-y \qquad \qquad (\ast)\end{eqnarray} in ...
José Hdz. Stgo.'s user avatar
4 votes
0 answers
332 views

Diophantine equations over cyclotomic fields

Let $\mathbb{Q}^{\text{ab}}$ be the compositum of all finite abelian extensions of $\mathbb{Q}$. Explicitly, $\mathbb{Q}^{\text{ab}}$ is the field obtained from $\mathbb{Q}$ by adjoining all roots of ...
Pablo's user avatar
  • 11.3k
1 vote
2 answers
349 views

Rational solutions to $P(x,y)=0$ for $P$ reducible over ${\mathbb C}$

There are facts in Mathematics that are so "obvious" and "well-known" that no-one includes a proper proof. An example is: Theorem: If polynomial $P(x,y)$ with rational coefficients ...
Bogdan Grechuk's user avatar
1 vote
1 answer
560 views

A good introduction to S unit equations

I was looking up some stuff when I stumbled across S unit equations. It seems to me that they are quite helpful in number theory, as given in this paper. http://faculty.nps.edu/pstanica/research/...
nb1's user avatar
  • 230