# Contraction of Cyclic Codes Over Finite Chain Rings

## TL;DR

This paper studies the structure of cyclic codes over finite chain rings, presenting a trace representation and analyzing how contractions of these codes relate to constacyclic codes under certain conditions.

## Contribution

It introduces a trace representation for cyclic codes over finite chain rings and characterizes contractions as constacyclic codes with specific parameters.

## Key findings

- Trace representation of cyclic codes over finite chain rings
- Contractions of cyclic codes yield constacyclic codes under gcd condition
- Characterization of code length and structure relationships

## Abstract

Let $\texttt{R}$ be a commutative finite chain ring of invariants $(q,s)$ and $\Gamma(\texttt{R})$ the Teichm\"uller's set of $\texttt{R}.$ In this paper, the trace representation cyclic $\texttt{R}$-linear codes of length $\ell,$ is presented, when $\texttt{gcd}(\ell, q) = 1.$ We will show that the contractions of some cyclic $\texttt{R}$-linear codes of length $u\ell$ are $\gamma$-constacyclic $\texttt{R}$-linear codes of length $\ell,$ where $\gamma\in\Gamma(\texttt{R})$ and the multiplicative order of is $u.$