Primes of the form X² + nY² in function fields

Let n be a square-free polynomial over F_q, where q is an odd prime power. In this work, we determine which irreducible polynomials p in F_q[x] can be represented in the form X^2+nY^2 with X, Y in F_q[x]. We restrict ourselves to the case where X^2+nY^2 is anisotropic at infinity. As in the classical case over Z, the representability of p by the quadratic form X^2+nY^2 is governed by conditions coming from class field theory. A necessary and almost sufficient condition is that the ideal generated by p splits completely in the Hilbert class field H of K=F_q(x,sqrt(-n)) for the appropriate notion of Hilbert class field in this context. In order to get explicit conditions for p to be of the form X^2+nY^2, we use the theory of sgn-normalized rank-one Drinfeld modules. We present an algorithm to construct a generating polynomial for H/K. This algorithm generalizes to all situations an algorithm of D.S.Dummit and D.Hayes for the case where -n is monic of odd degree.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Applied Mathematics

Grantor

Mathematics

Year dc:date.available

2010

Author dc:creator

• Maciak, Piotr

• weak representation
• strong representation
• principal form
• normalizing field
• j-invariant

Statement dc:rights

• unrestricted
• Release the entire work immediately for access worldwide.

Identifier

etd-04272010-174411
https://repository.lsu.edu/gradschool_dissertations/902

OAI identifier oai:identifier

oai:repository.lsu.edu:gradschool_dissertations-1901