Optimal Two-Dimensional Reed--Solomon Codes Correcting Insertions and Deletions
Roni Con, Amir Shpilka, Itzhak Tamo
TL;DR
The paper resolves the minimal field-size question for constructing $[n,2]_q$ Reed–Solomon codes that can correct $n-3$ insdel errors by giving explicit constructions over the cubic extension field $\mathbb{F}_{q^3}$ with $q = O(n^3)$. It uses an algebraic Vandermonde-type determinant condition to certify insdel-correcting capability and provides two variants that work for all characteristics and, for odd characteristic, yield longer codes. It also proves a near-tight lower bound $q \ge \binom{n}{3}-1$, establishing near-optimality of the cubic-field-size construction. This advances practical insdel-robust RS-code designs and tightens the field-size bounds for two-dimensional RS codes under synchronization errors.
Abstract
Constructing Reed--Solomon (RS) codes that can correct insertions and deletions (insdel errors) has been considered in numerous recent works. For the special case of two-dimensional RS-codes, it is known [CST23] that an $[n,2]_q$ RS-code that can correct from $n-3$ insdel errors satisfies that $q=Ω(n^3)$. On the other hand, there are several known constructions of $[n,2]_q$ RS-codes that can correct from $n-3$ insdel errors, where the smallest field size is $q=O(n^4)$. In this short paper, we construct $[n,2]_q$ Reed--Solomon codes that can correct $n-3$ insdel errors with $q=O(n^3)$, thereby resolving the minimum field size needed for such codes.
