Every cubic form over integers in 14 variables has a non-trivial zero

You need to know: Polynomial in n variables.

Background: A cubic form over integers in n variables is the polynomial of the form P(x_1, x_2, \dots, x_n)=\sum\limits_{i=1}^n \sum\limits_{j=1}^n \sum\limits_{k=1}^n c_{ijk}x_ix_jx_k, where c_{ijk} are integer coefficients.

The Theorem: On 8th June 2006, Roger Heath-Brown submitted to Inventiones mathematicae a paper in which he proved that, for every cubic form P(x_1, x_2, \dots, x_n) over integers in n\geq 14 variables, there exists integers x^*_1, x^*_2, \dots, x^*_n, not all zero, such that P(x^*_1, x^*_2, \dots, x^*_n)=0.

Short context: The classical 1884 Theorem of Meyer states that any indefinite quadratic from (a quadratic from P(x_1, x_2, \dots, x_n)=\sum\limits_{i=1}^n \sum\limits_{j=1}^n c_{ij}x_ix_j is indefinite if it is less than 0 for some values of variables and greater than 0 for others) over integers in n\geq 5 variables has a non-trivial zero. All cubic forms are indefinite, and it is conjectured that they must have a non-trivial zero if n \geq 10. In 1963, Davenport proved this for n\geq 16. After more then 40 years with no further progress, the Theorem proves this for n\geq 14.

Links: The original paper is available here.

Go to the list of all theorems

Leave a comment