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In this paper motivated from subspace coding we introduce subspace-metric codes and subset-metric codes. These are coordinate-position independent pseudometrics and suitable for the folded codes. The half-Singleton upper bounds for linear…

Information Theory · Computer Science 2021-10-20 Hao Chen

Let $\Gamma$ denote a distance-regular graph. The maximum size of codewords with minimum distance at least $d$ is denoted by $A(\Gamma,d)$. Let $\square_n$ denote the folded $n$-cube $H(n,2)$. We give an upper bound on $A(\square_n,d)$…

Combinatorics · Mathematics 2018-01-23 Lihang Hou , Bo Hou , Suogang Gao , Wei-Hsuan Yu

In this work we investigate unions of lifted MRD codes of a fixed dimension and minimum distance and derive an explicit formula for the cardinality of such codes. This will then imply a lower bound on the cardinality of constant dimension…

Information Theory · Computer Science 2013-01-10 Anna-Lena Trautmann

Codes in finite projective spaces equipped with the subspace distance have been proposed for error control in random linear network coding. The resulting so-called \emph{Main Problem of Subspace Coding} is to determine the maximum size…

Combinatorics · Mathematics 2018-08-30 Thomas Honold , Michael Kiermaier , Sascha Kurz

The paper investigates uniformly closed subspaces, sublattices, and ideals of finite codimension in Archimedean vector lattices. It is shown that every uniformly closed subspace (or sublattice) of finite codimension may be written as an…

Functional Analysis · Mathematics 2024-03-13 Eugene Bilokopytov , Vladimir G. Troitsky

A subspace code is a nonempty set of subspaces of a vector space $\mathbb F^n_q$. Linear codes with complementary duals, or LCD codes, are linear codes whose intersection with their duals is trivial. In this paper, we introduce a notion of…

Combinatorics · Mathematics 2023-05-04 Dean Crnkovic , Andrea Svob

We show an interesting PBD-closure result for the set of lengths of constant-composition codes whose distance and size meet certain conditions. A consequence of this PBD-closure result is that the size of optimal constant-composition codes…

Information Theory · Computer Science 2007-12-18 Yeow Meng Chee , Alan C. H. Ling , San Ling , Hao Shen

Equidistant codes over vector spaces are considered. For $k$-dimensional subspaces over a large vector space the largest code is always a sunflower. We present several simple constructions for such codes which might produce the largest…

Combinatorics · Mathematics 2015-05-06 Tuvi Etzion , Netanel Raviv

We show that, for vector spaces in which distance measurement is performed using a gauge, the existence of best coapproximations in $1$-codimensional closed linear subspaces implies in dimensions $\geq 2$ that the gauge is a norm, and in…

Metric Geometry · Mathematics 2021-01-15 Thomas Jahn , Christian Richter

A subspace code is defined as a collection of subspaces of an ambient vector space, where each information-encoding codeword is a subspace. This paper studies a class of spatial sensing problems, notably direction of arrival (DoA)…

Signal Processing · Electrical Eng. & Systems 2024-07-04 Hessam Mahdavifar , Robin Rajamäki , Piya Pal

We show that large subsets of vector spaces over finite fields determine certain point configurations with prescribed distance structure. More specifically, we consider the complete graph with vertices as the points of $A \subseteq…

Combinatorics · Mathematics 2018-02-20 Alex Iosevich , Hans Parshall

We describe a novel extension of subspace codes for noncoherent networks, suitable for use when the network is viewed as a communication system that introduces both dimension and symbol errors. We show that when symbol erasures occur in a…

Information Theory · Computer Science 2012-09-25 Vitaly Skachek , Olgica Milenkovic , Angelia Nedic

It is known that for a variety of choices of metrics, including the standard bottleneck distance, the space of persistence diagrams admits geodesics. Typically these existence results produce geodesics that have the form of a convex…

Metric Geometry · Mathematics 2019-05-28 Samir Chowdhury

For a given curve X and divisor class C, we give lower bounds on the degree of a divisor A such that A and A-C belong to specified semigroups of divisors. For suitable choices of the semigroups we obtain (1) lower bounds for the size of a…

Number Theory · Mathematics 2008-10-17 Iwan M. Duursma , Seungkook Park

It is reasonable to expect the theory of quantum codes to be simplified in the case of codes of minimum distance 2; thus, it makes sense to examine such codes in the hopes that techniques that prove effective there will generalize. With…

Quantum Physics · Physics 2007-05-23 Eric M. Rains

We consider the longest common subsequence problem in the context of subsequences with gap constraints. In particular, following Day et al. 2022, we consider the setting when the distance (i. e., the gap) between two consecutive symbols of…

Data Structures and Algorithms · Computer Science 2023-06-05 Duncan Adamson , Maria Kosche , Tore Koß , Florin Manea , Stefan Siemer

Convex neural codes are subsets of the Boolean lattice that record the intersection patterns of convex sets in Euclidean space. Much work in recent years has focused on finding combinatorial criteria on codes that can be used to classify…

Combinatorics · Mathematics 2020-12-18 R. Amzi Jeffs , Caitlin Lienkaemper , Nora Youngs

Two tantalizing invariants of a combinatorial code $\mathcal C\subseteq 2^{[n]}$ are cdim$(\mathcal C)$ and odim$(\mathcal C)$, the smallest dimension in which $\mathcal C$ can be realized by convex closed or open sets, respectively. Cruz,…

Combinatorics · Mathematics 2022-07-19 R. Amzi Jeffs

The maximum size of $t$-intersecting families is one of the most celebrated topics in combinatorics, and its size is known as the Erd\H{o}s-Ko-Rado theorem. Such intersecting families, also known as constant-weight anticodes in coding…

Combinatorics · Mathematics 2025-03-20 Xuan Wang , Tuvi Etzion , Denis Krotov , Minjia Shi

Using the correspondence between quadrics of ${\rm PG}(2,q)$ and points of ${\rm PG}(5,q)$, a family of $(6,q^3(q^2-1)(q-1)/3+(q^2+1)(q^2+q+1),4;3)_q$ constant dimension subspace codes is constructed.

Combinatorics · Mathematics 2015-06-02 Antonio Cossidente , Francesco Pavese