Self-dual matrix codes over Galois rings

MacWilliams' Extension Theorem for bi-invariant weights over finite principal ideal rings

This paper presents a coding theorem for linear coding over finite rings, in the setting of the Slepian–Wolf source coding problem. This theorem covers corresponding achievability theorems of Elias (IRE Conv. Rec. 1955, 3, 37–46) and Csiszár (IEEE Trans. Inf. Theory 1982, 28, 585–592) for linear coding over finite fields as special cases. In addition, it is shown that, for any set of finite correlated discrete memoryless sources, there always exists a sequence of linear encoders over some finite non-field rings which achieves the data compression limit, the Slepian–Wolf region. Hence, the optimality problem regarding linear coding over finite non-field rings for data compression is closed with positive confirmation with respect to existence. For application, we address the problem of source coding for computing, where the decoder is interested in recovering a discrete function of the data generated and independently encoded by several correlated i.i.d. random sources. We propose linear coding over finite rings as an alternative solution to this problem. Results in Körner–Marton (IEEE Trans. Inf. Theory 1979, 25, 219–221) and Ahlswede–Han (IEEE Trans. Inf. Theory 1983, 29, 396–411, Theorem 10) are generalized to cases for encoding (pseudo) nomographic functions (over rings). Since a discrete function with a finite domain always admits a nomographic presentation, we conclude that both generalizations universally apply for encoding all discrete functions of finite domains. Based on these, we demonstrate that linear coding over finite rings strictly outperforms its field counterpart in terms of achieving better coding rates and reducing the required alphabet sizes of the encoders for encoding infinitely many discrete functions.

Several problems in algebraic geometry and coding theory over finite rings are modeled by systems of algebraic equations. Among these problems, we have the rank decoding problem, which is used in the construction of public-key cryptosystems. A finite chain ring is a finite ring admitting exactly one maximal ideal and every ideal being generated by one element. In 2004, Nechaev and Mikhailov proposed two methods for solving systems of polynomial equations over finite chain rings. These methods used solutions over the residue field to construct all solutions step by step. However, for some types of algebraic equations, one simply needs partial solutions. In this paper, we combine two existing approaches to show how Gröbner bases over finite chain rings can be used to solve systems of algebraic equations over finite commutative rings. Then, we use skew polynomials and Plücker coordinates to show that some algebraic approaches used to solve the rank decoding problem and the MinRank problem over finite fields can be extended to finite principal ideal rings.

A construction of finite Frobenius rings and its application to partial difference sets

Let S be an F -finite regular local ring and I an ideal contained in S. Let R = S/I. Fedder proved that R is F -pure if and only if (I [p] : I) * m[p]. We have noted a new proof for his criterion, along with showing that (I [q] : I) ⊆ (τ [q] : τ), where τ is the pullback of the test ideal for R. Combining the the F -purity criterion and the above result we see that if R = S/I is F pure then R/τ is also F -pure. In fact, we can form a filtration of R, I ⊆ τ = τ0 ⊆ τ1 ⊆ . . . ⊆ τi ⊆ . . . that stabilizes such that each R/τi is F -pure and its test ideal is τi+1. To find examples of these filtrations we have made explicit calculations of test ideals in the following setting: Let R = T/I, where T is either a polynomial or a power series ring and I = P1 ∩ . . . ∩ Pn is generated by monomials and the R/Pi are regular. Set J = Σ(P1 ∩ . . . ∩ Pi ∩ . . . ∩ Pn). Then J = τ = τpar. This paper concerns the study of the test ideal in F -finite quotients of regular local rings. Test elements play a key role in tight closure theory. Once known, they make computing tight closures of ideals and modules easier. In fact, in an excellent Gorenstein local ring with an isolated singularity, R/τ ∼= Hom(I∗/I, E) where I is generated by a system of parameters that are test elements and E is the injective hull of R (see [Hu1] and [S1]). We also know for parameter ideals I that I : τ = I∗. Thus knowing τ is basically equivalent to knowing the tight closure of a system of parameters which is contained in the test ideal. A recent paper of Huneke and Smith [HS] links tight closure to Kodaira vanishing for graded rings R with characteristic either 0 or p where p 0. Recall that the a-invariant for a graded ring R, denoted a, is equal to −min{i|[ωR]i 6= 0}, where ωR is the canonical module for R. If R is Gorenstein, then ωR = R(a). Huneke and Smith prove that the test ideal is exactly the ideal generated by elements of degree greater than the a-invariant of R if and only if a strong Kodaira vanishing holds on R. A recent paper of Hara [Ha] confirms that this strong Kodaira vanishing holds in finitely generated algebras over a field of characteristic zero. In this paper we study test ideals of F -finite rings which are reduced quotients of a regular local ring. Reduced quotients of F -finite regular local rings have been studied by both Fedder [Fe] and Glassbrenner [Gl]. Fedder’s work concerns F purity aspects of these rings, and Glassbrenner’s results use Fedder’s techniques to examine strong F -regularity. The object that plays a key role in their work is Received by the editors November 4, 1996. 1991 Mathematics Subject Classification. Primary 13A35.

It is shown that a finite ring R is a Frobenius ring if and only if $_R(R/\hbox {Rad}\, R)\cong \hbox {Soc}\, (_RR)$ . Other combinatorial characterizations of finite Frobenius rings are presented which have applications in the theory of linear codes over finite rings.

Various forms of the extension problem are discussed for linear codes defined over finite rings. The extension theorem for symmetrized weight compositions over finite Frobenius rings is proved. As a consequence, an extension theorem for weight functions over certain finite commutative rings is also proved. The proofs make use of the linear independence of characters as well as the linear independence of characters averaged over the orbits of a group action.

On the ℓ-DLIPs of codes over finite commutative rings

On the groups of units of finite commutative chain rings

In this paper, we propose three new turn-based two player roulette games and provide positional winning strategies for these games in terms of depths of words over finite commutative rings with unity. We further discuss the feasibility of these winning strategies by studying depths of codewords of all repeated-root $$(\alpha +\gamma \beta )$$ -constacyclic codes of prime power lengths over a finite commutative chain ring $${\mathcal {R}},$$ where $$\alpha $$ is a non-zero element of the Teichmuller set of $${\mathcal {R}},$$ $$\gamma $$ is a generator of the maximal ideal of $${\mathcal {R}}$$ and $$\beta $$ is a unit in $${\mathcal {R}}.$$ As a consequence, we explicitly determine depth distributions of all repeated-root $$(\alpha +\gamma \beta )$$ -constacyclic codes of prime power lengths over $${\mathcal {R}}$$ .

Circulant matrices form an important class of matrices that have been continuously studied due to their nice algebraic structures and wide applications. In this study, we focus specifically on negacirculant matrices, which are known as extensions of the classical circulant matrices. The algebraic structures of the rings of n × n n\times n negacirculant matrices over finite fields and over finite commutative chain rings are presented. Subsequently, the algebraic structures and enumeration of the unit groups of such matrix rings are established. Additionally, the number of non-singular n × n n\times n negacirculant matrices with prescribed determinant is given in some cases. Conjectures and open problems are proposed as well as a brief discussion in the case where the underlying ring is a finite commutative ring with identity is also presented.

Let $R$ be a ring (not necessarily commutative) with nonzero identity. We define $Gamma(R)$ to be the graph with vertex set $R$ in which two distinct vertices $x$ and $y$ are adjacent if and only if there exist unit elements $u,v$ of $R$ such that $x+uyv$ is a unit of $R$. In this paper, basic properties of $Gamma(R)$ are studied. We investigate connectivity and the girth of $Gamma(R)$, where $R$ is a left Artinian ring. We also determine when the graph $Gamma(R)$ is a cycle graph. We prove that if $Gamma(R)congGamma(M_{n}(F))$ then $Rcong M_{n}(F)$, where $R$ is a ring and $F$ is a finite field. We show that if $R$ is a finite commutative semisimple ring and $S$ is a commutative ring such that $Gamma(R)congGamma(S)$, then $Rcong S$. Finally, we obtain the spectrum of $Gamma(R)$, where $R$ is a finite commutative ring.

We consider irreversible Markov chains on finite commutative rings randomly generated using both addition and multiplication. We restrict ourselves to the case where the addition is uniformly random and multiplication is arbitrary. We first prove formulas for eigenvalues and multiplicities of the transition matrices of these chains using the character theory of finite abelian groups. The examples of principal ideal rings (such as $\mathbb{Z}_{n}$) and finite chain rings (such as $\mathbb{Z}_{p^k}$) are particularly illuminating and are treated separately. We then prove a recursive formula for the stationary probabilities for any ring, and use it to prove explicit formulas for the probabilities for finite chain rings when multiplication is also uniformly random. Finally, we prove constant mixing time for our chains using coupling.

Non-invertible-element constacyclic codes over finite PIRs

Introduction. The problem of mathematical safe arises in the theory of computer games and cryptographic applications. The article considers numerous variations of the mathematical safe problem and examples of its solution using systems of linear Diophantine equations in finite rings and fields. The purpose of the article. To present methods for solving the problem of a mathematical safe for its various variations, which are related both to the domain over which the problem is considered and to the structure of systems of linear equations over these domains. To consider the problem of a mathematical safe (in matrix and graph forms) in different variations over different finite domains and to demonstrate the work of methods for solving this problem and their efficiency (systems over finite simple fields, finite fields, ghost rings and finite associative-commutative rings). Results. Examples of solving the problem of a mathematical safe, the conditions for the existence of solutions in different areas, over which this problem is considered. The choice of the appropriate area over which the problem of the mathematical safe is considered, and the appropriate algorithm for solving it depends on the number of positions of the latches of the safe. All these algorithms are accompanied by estimates of their time complexity, which were considered in the first part of this paper. Conclusions. The considered methods and algorithms for solving linear equations and systems of linear equations in finite rings and fields allow to solve the problem of a mathematical safe in a large number of variations of its formulation (over finite prime field, finite field, primary associative-commutative ring and finite associative-commutative ring with unit). Keywords: mathematical safe, finite rings, finite fields, method, algorithm.