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In this paper, we use a novel approach to describe generator polynomials of quasi-cyclic (QC) and generalized QC (GQC) codes over finite fields. Our study of QC- and GQC-codes will be general and not only restricted to one-generator codes. We prove that generator polynomials of QC-codes and GQC-codes are unique. Further, we use our results to obtain an expression for the dimensions of QC-codes and GQC-codes. As an application of our construction of these codes, we obtain many optimal linear codes over finite fields GF (2) , GF (3) , GF (4) and GF (5). [ABSTRACT FROM AUTHOR]

In this paper, we will study the structure of ℤ 4 R -additive codes where ℤ 4 = { 0 , 1 , 2 , 3 } is the well-known ring of 4 elements and R is the ring given by R = ℤ 4 + u ℤ 4 + v ℤ 4 , where u 2 = u , v 2 = v and u v = v u = 0. We will classify all maximum distance separable codes with respect to the Singleton bound (MDSS) over ℤ 4 R. Then we will focus on ℤ 4 R -additive cyclic and constacyclic codes. We will find a unique set of generator polynomials for these codes and determine minimum spanning sets for them. We will also find the generator polynomials for the dual of any ℤ 4 R -additive cyclic or constacyclic code. [ABSTRACT FROM AUTHOR]

Let 𝔽 4 be the field of four elements. We denote by R the commutative ring, with 1 6 elements, 𝔽 4 + v 𝔽 4 : = { a + v b | a , b ∈ 𝔽 4 } with v 2 = v. This work defines linear codes over the ring of mixed alphabets 𝔽 4 R as well as their dual codes under a nondegenerate inner product. We then derive the systematic form of the respective generator matrices of the codes and their dual codes. We wrap the paper up by proving the MacWilliams identity for linear codes over 𝔽 4 R. [ABSTRACT FROM AUTHOR]

In this paper, we introduce self-dual cyclic codes over the ring ℤ 2 × (ℤ 2 + u ℤ 2) = ℤ 2 ℤ 2 [ u ]. We determine the conditions for any ℤ 2 ℤ 2 [ u ] -cyclic code to be self-dual, that is, 𝒞 = 𝒞 ⊥ . Since the binary image of a self-orthogonal ℤ 2 ℤ 2 [ u ] -linear code is also a self-orthogonal binary linear code, we introduce quantum codes over ℤ 2 ℤ 2 [ u ]. Finally, we present some examples of self-dual cyclic and quantum codes that have good parameters. [ABSTRACT FROM AUTHOR]

ℤ 2 ℤ 2 s -additive codes for any integer s > 1 are considered as codes over mixed alphabets. They are a generalization of binary linear codes and linear codes over ℤ 2 s . In this paper, we are interested in studying ℤ 2 ℤ 2 s -additive cyclic codes. We will give the generator polynomials of these codes. We will also give the minimal spanning sets for these codes. We will define separable ℤ 2 ℤ 2 s -additive codes and provide conditions on the generator polynomials for a ℤ 2 ℤ 2 s -additive cyclic code to be separable. Finally, we present some examples of optimal parameter binary codes obtained as images of ℤ 2 ℤ 8 -additive cyclic codes. [ABSTRACT FROM AUTHOR]

Motivated by a generalization of the football pool problem, we introduce additive cyclic codes over mixed alphabets of the form where , for distinct primes . We study their algebraic properties, generating sets, and duals. Additionally, we give examples of additive cyclic codes over the alphabet that have best-known or optimal parameters. [ABSTRACT FROM AUTHOR]

Additive codes received much attention due to their connections with quantum codes. On the other hand, skew cyclic codes proved to be a useful class of codes that contain many good codes. In this work, we introduce and study additive skew cyclic codes over the quaternary field , obtaining some structural properties of these codes. Moreover, we also show that many best known and optimal quantum codes can be obtained from this class. [ABSTRACT FROM AUTHOR]