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List-Decoding Capacity Implies Capacity on the q-ary Symmetric Channel

Francisco Pernice, Oscar Sprumont, Mary Wootters

TL;DR

It is shown that there is any linear code C⊆ Fqn that has superconstant minimum distance and achieves list-decoding capacity also achieves capacity on the qSC.

Abstract

It is known that the Shannon capacity of the q-ary symmetric channel (qSC) is the same as the list-decoding capacity of an adversarial channel, raising the question of whether there is a formal (and black-box) connection between the two. We show that there is: Any linear code $C\subseteq \mathbb{F}_q^n$ that has minimum distance $d_{\min}=ω(q^3)$ and achieves list-decoding capacity also achieves capacity on the qSC.

List-Decoding Capacity Implies Capacity on the q-ary Symmetric Channel

TL;DR

It is shown that there is any linear code C⊆ Fqn that has superconstant minimum distance and achieves list-decoding capacity also achieves capacity on the qSC.

Abstract

It is known that the Shannon capacity of the q-ary symmetric channel (qSC) is the same as the list-decoding capacity of an adversarial channel, raising the question of whether there is a formal (and black-box) connection between the two. We show that there is: Any linear code that has minimum distance and achieves list-decoding capacity also achieves capacity on the qSC.

Paper Structure

This paper contains 20 sections, 12 theorems, 99 equations.

Key Result

Theorem 1

Let $p \in (0,1)$. Let $\{C_n\subseteq\mathbb{F}_{q}^n\}$ be a family of linear codes that achieves list-decoding capacity on the adversarial channel that introduces a $p$-fraction of corruptions. If $d_{\min}(C_n)=\omega(\frac{q^3}{(1-p)^2})$, then $\{C_n\}$ achieves capacity on the qSC$_p$.

Theorems & Definitions (28)

  • Theorem 1
  • Theorem 2
  • Remark 1: Requirement on the field size
  • Theorem 3
  • Remark 2: New results for capacity-achieving codes on the qSC$_p$?
  • Lemma 4: Hoeffding's Inequality
  • Definition 1
  • Definition 2
  • Theorem 7
  • proof
  • ...and 18 more