On Some Constacyclic Codes Over Z4[u]/〈u² - 1〉, Their Z4 Images, and New Codes

Abstract

In this paper, we study λ-constacyclic codes over the ring R= Z<inf>4</inf>+ uZ<inf>4</inf> where u2= 1 , for λ= 3 + 2 u and 2 + 3 u. Two new Gray maps from R to Z43 are defined with the goal of obtaining new linear codes over Z<inf>4</inf>. The Gray images of λ-constacyclic codes over R are determined. We then conducted a computer search and obtained many λ-constacyclic codes over R whose Z<inf>4</inf>-images have better parameters than currently best-known linear codes over Z<inf>4</inf>. © 2017, Springer Science+Business Media, LLC.