Additive cyclic codes over finite commutative chain rings

Additive cyclic codes over Galois rings were investigated in Cao et al. (2015). In this paper, we investigate the same problem but over a more general ring family, finite commutative chain rings. When we focus on non-Galois finite commutative chain rings, we observe two different kinds of additivity. One of them is a natural generalization of the study in Cao et al. (2015), whereas the other one has some unusual properties especially while constructing dual codes. We interpret the reasons of such properties and illustrate our results giving concrete examples.     

A relation between quasi-cyclic codes and 2-D cyclic codes

We consider a q-ary quasi-cyclic code C of length m? and index ?, where both m and ? are relatively prime to q. If the constituents of C are cyclic codes, we show that C can also be viewed as a 2-D cyclic code of size $m\times ?$ over ${\mathbb{F}}_q$. In case m and ? are also coprime to each other, we easily observe that the code C must be equivalent to a cyclic code, which was proved earlier by Lim.     

Cyclic subspace codes via subspace polynomials

Subspace codes have been intensely studied in the last decade due to their application in random network coding. In particular, cyclic subspace codes are very useful subspace codes with their efficient encoding and decoding algorithms. In a recent paper, Ben-Sasson et al. gave a systematic construction of subspace codes using subspace polynomials. In this paper, we mainly generalize and improve their result so that we can obtain larger codes for fixed parameters and also we can increase the density of some possible parameters. In addition, we give some relative remarks and explicit examples.     

Improvements on Generalized Hamming Weights of Some Trace Codes

We obtain improved bounds for the generalized Hamming weights of some trace codes which include a large class of cyclic codes over any finite field. In particular, we improve the corresponding bounds of Stichtenoth and Voss [8] using various methods altogether.     

A new class of quaternary LCZ sequence sets

In this article, we present a construction of low correlation zone (LCZ) sequence sets. This construction gives a new class of quaternary LCZ sequence sets. Furthermore, we observe a generalization of the LCZ sequence sets in Kim et al. (IEEE Trans Inform Theory 52(10):4607–4616, 2006) by using an orthogonal transformation. The obtained LCZ sequence sets are optimal with respect to the Tang, Fan and Matsufuji bound.     

Finite number of fibre products of Kummer covers and curves with many points over finite fields

We study fibre products of a finite number of Kummer covers of the projective line over finite fields. We determine the number of rational points of the fibre product over a rational point of the projective line, which improves the results of Özbudak and Temür (Appl Algebra Eng Commun Comput 18:433–443, 2007) substantially. We also construct explicit examples of fibre products of Kummer covers with many rational points, including a record and two new entries for the current table (http://www.manypoints.org, 2011).     

Elements of Prescribed Order,Prescribed Traces and Systems of Rational Functions Over Finite Fields

Let k 1 and be a system of rational functions forming a strongly linearly independent set over a finite field . Let be arbitrarily prescribed elements. We prove that for all sufficiently large extensions , there is an element of prescribed order such that is the relative trace map from onto We give some applications to BCH codes, finite field arithmetic and ordered orthogonal arrays. We also solve a question of Helleseth et~al. (Hypercubic 4 and 5-designs from Double-Error-Correcting codes, Des. Codes. Cryptgr. 28(2003). pp. 265–282) completely.classification 11T30, 11G20, 05B15     

Imprimitive symmetric association schemes of classes 5 and 6 arising from ternary non-weakly regular bent functions

Journal of Algebraic Combinatorics - Let F be a ternary non-weakly regular bent function in GMMF class whose dual $$F^*$$ is bent. We prove that if F satisfies certain conditions, then collecting...