CNTA-VII: CRM Proceedings & Lecture Notes
We describe a general three step method for constructing number fields with Lie-type Galois groups and discriminants factoring into powers of specified primes. The first step involves extremal solutions of the matrix equation ABC = I. The second step involves extremal polynomial solutions of the equation A(x) + B(x) + C(x) = 0. The third step involves integer solutions of the generalized Fermat equation axp + byq + czr = 0. We concentrate here on details associated to the third step and give examples where the field discriminants have the form ±2a3b .
David P. Roberts. An ABC construction of number fields. CNTA-VII, CRM Proceedings and Lecture Notes 36 (2004), 237-267.