List-decoding of AG codes without genus penalty

Peter Beelen, Maria Montanucci
Mathematics, Algebraic Geometry, Algebraic Geometry (math.AG), Information Theory (cs.IT)
2023-07-08 16:00:00
In this paper we consider algebraic geometry (AG) codes: a class of codes constructed from algebraic codes (equivalently, using function fields) by Goppa. These codes can be list-decoded using the famous Guruswami-Sudan (GS) list-decoder, but the genus $g$ of the used function field gives rise to negative term in the decoding radius, which we call the genus penalty. In this article, we present a GS-like list-decoding algorithm for arbitrary AG codes, which we call the \emph{inseparable GS list-decoder}. Apart from the multiplicity parameter $s$ and designed list size $\ell$, common for the GS list-decoder, we introduce an inseparability exponent $e$. Choosing this exponent to be positive gives rise to a list-decoder for which the genus penalty is reduced with a factor $1/p^e$ compared to the usual GS list-decoder. Here $p$ is the characteristic. Our list-decoder can be executed in $\tilde{\mathcal{O}}(s\ell^{\omega}\mu^{\omega-1}p^e(n+g))$ field operations, where $n$ is the code length.
PDF: List-decoding of AG codes without genus penalty.pdf
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