dorsal/arxiv
View SchemaOptimal Proximity Gap for Folded Reed--Solomon Codes via Subspace Designs
| Authors | Fernando Granha Jeronimo, Lenny Liu, Pranav Rajpal |
|---|---|
| Categories | |
| ArXiv ID | 2601.10047vv1 |
| URL | https://arxiv.org/abs/2601.10047 |
| License | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ |
Abstract
A collection of sets satisfies a $(\delta,\varepsilon)$-proximity gap with respect to some property if for every set in the collection, either (i) all members of the set are $\delta$-close to the property in (relative) Hamming distance, or (ii) only a small $\varepsilon$-fraction of members are $\delta$-close to the property. In a seminal work, Ben-Sasson \textit{et al.}\ showed that the collection of affine subspaces exhibits a $(\delta,\varepsilon)$-proximity gap with respect to the property of being Reed--Solomon (RS) codewords with $\delta$ up to the so-called Johnson bound for list decoding. Their technique relies on the Guruswami--Sudan list decoding algorithm for RS codes, which is guaranteed to work in the Johnson bound regime. Folded Reed--Solomon (FRS) codes are known to achieve the optimal list decoding radius $\delta$, a regime known as capacity. Moreover, a rich line of list decoding algorithms was developed for FRS codes. It is then natural to ask if FRS codes can be shown to exhibit an analogous $(\delta,\varepsilon)$-proximity gap, but up to the so-called optimal capacity regime. We answer this question in the affirmative (and the framework naturally applies more generally to suitable subspace-design codes). An additional motivation to understand proximity gaps for FRS codes is the recent results [BCDZ'25] showing that they exhibit properties similar to random linear codes, which were previously shown to be related to properties of RS codes with random evaluation points in [LMS'25], as well as codes over constant-size alphabet based on AEL [JS'25].
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"abstract": "A collection of sets satisfies a $(\\delta,\\varepsilon)$-proximity gap with respect to some property if for every set in the collection, either (i) all members of the set are $\\delta$-close to the property in (relative) Hamming distance, or (ii) only a small $\\varepsilon$-fraction of members are $\\delta$-close to the property.\n In a seminal work, Ben-Sasson \\textit{et al.}\\ showed that the collection of affine subspaces exhibits a $(\\delta,\\varepsilon)$-proximity gap with respect to the property of being Reed--Solomon (RS) codewords with $\\delta$ up to the so-called Johnson bound for list decoding. Their technique relies on the Guruswami--Sudan list decoding algorithm for RS codes, which is guaranteed to work in the Johnson bound regime.\n Folded Reed--Solomon (FRS) codes are known to achieve the optimal list decoding radius $\\delta$, a regime known as capacity. Moreover, a rich line of list decoding algorithms was developed for FRS codes. It is then natural to ask if FRS codes can be shown to exhibit an analogous $(\\delta,\\varepsilon)$-proximity gap, but up to the so-called optimal capacity regime. We answer this question in the affirmative (and the framework naturally applies more generally to suitable subspace-design codes).\n An additional motivation to understand proximity gaps for FRS codes is the recent results [BCDZ\u002725] showing that they exhibit properties similar to random linear codes, which were previously shown to be related to properties of RS codes with random evaluation points in [LMS\u002725], as well as codes over constant-size alphabet based on AEL [JS\u002725].",
"arxiv_id": "2601.10047",
"authors": [
"Fernando Granha Jeronimo",
"Lenny Liu",
"Pranav Rajpal"
],
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"cs.IT",
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"license": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
"title": "Optimal Proximity Gap for Folded Reed--Solomon Codes via Subspace Designs",
"url": "https://arxiv.org/abs/2601.10047",
"version": "v1"
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