Binary Reconstruction Codes for Correcting One Deletion and One Substitution
Yuling Li, Yubo Sun, Gennian Ge
TL;DR
This work studies reconstruction codes for channels that introduce one deletion and one substitution, formalized via the single-deletion single-substitution ball $\mathcal{B}$. The authors bound the worst-case intersection $|\mathcal{B}(\bm{x}) \cap \mathcal{B}(\bm{y})|$ by decomposing into deletion and substitution components with parameters $(d,s)\in\{(0,0),(1,0),(2,0),(0,2),(1,2),(2,2)\}$, leveraging $|\mathcal{D}(\bm{x},\bm{y})|=d$ and $|\mathcal{S}(\bm{x},\bm{y})|=s$, and thereby construct reconstruction codes with explicit redundancies for several target $N$. The paper deploys VT-based and run-length constrained schemes, often constrained by the inversion number $\mathrm{Inv}(\cdot)$ modulo small moduli, and, in some cases, combines these with list-decodable constructions. Key results include redundancy $0$ for $N=4n-8$, $1$ for $N=3n-4$, $2$ for $N=2n+9$, $\log\log n+3$ for $N=n+21$, $\log n+1$ for $N=31$, and $3\log n+4$ for $N=7$. These constructions demonstrate explicit binary codes achieving near-optimal reconstruction capabilities with sublinear or logarithmic redundancies, enabling unique or list-decodable reconstructions from a fixed number of noisy outputs. The results advance sequence reconstruction theory for combined deletion and substitution errors and have potential applications in DNA storage and racetrack memory where robust data integrity under multiple error types is essential.
Abstract
In this paper, we investigate binary reconstruction codes capable of correcting one deletion and one substitution. We define the \emph{single-deletion single-substitution ball} function $ \mathcal{B} $ as a mapping from a sequence to the set of sequences that can be derived from it by performing one deletion and one substitution. A binary \emph{$(n,N;\mathcal{B})$-reconstruction code} is defined as a collection of binary sequences of length $ n $ such that the intersection size between the single-deletion single-substitution balls of any two distinct codewords is strictly less than $ N $. This property ensures that each codeword can be uniquely reconstructed from $ N $ distinct elements in its single-deletion single-substitution ball. Our main contribution is to demonstrate that when $ N $ is set to $ 4n - 8 $, $ 3n - 4 $, $2n+9$, $ n+21 $, $31$, and $7$, the redundancy of binary $(n,N;\mathcal{B})$-reconstruction codes can be $0$, $1$, $2$, $ \log\log n + 3 $, $\log n + 1 $, and $ 3\log n + 4 $, respectively, where the logarithm is on base two.
