arXiv subjects
Publications and source records attributed to Ekin Özman.
In this paper, we study cyclic and constacyclic codes over the finite chain ring R=Z4+iZ4, where i^2=-1. We prove that all constacyclic codes over R are equivalent to cyclic codes. An algorithm to obtain generators for all simple root constacyclic codes over R is presented. Using a Gray map we then obtain linear Z4 codes from constacyclic codes over R. We present new best linear Z4 codes found using this method.
In this paper, we investigate solutions to the Diophantine equation $ A a^p + B b^p = C c^3 $ over number fields using the modular method. Assuming certain standard modularity conjectures, we first establish an asymptotic result for general number fields satisfying an appropriate $S$-unit condition. In particular, we verify that this condition holds for several imaginary quadratic fields. Beyond the asymptotic setting, we also obtain an effective result. Specifically, for the equation $a^p + d b^p = c^3$ over $ K = \mathbb{Q}(\sqrt{-d}) $ with $ d \in \{7, 19, 43, 67\} $, we determine an explicit bound (depending on $ d $) such that no solutions of a certain type exist whenever $ p $ exceeds this bound.
In this paper, we use the modular method over totally real fields together with some standard conjectures (the Weak Frey--Mazur Conjecture and the Eichler--Shimura Conjecture) to prove that infinitely many equations of the type $x^r+y^r=Dz^p$ do not have any non-trivial primitive integer solutions, where $r \geq 5$ is a fixed prime, whenever $p$ is large enough. For $r \equiv 3 \pmod 4$, we get the same result with only assuming the Weak Frey--Mazur Conjecture.