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An extension of the order bound for AG codes (0901.2864v1)

Published 19 Jan 2009 in math.NT, cs.IT, math.AG, and math.IT

Abstract: The most successful method to obtain lower bounds for the minimum distance of an algebraic geometric code is the order bound, which generalizes the Feng-Rao bound. We provide a significant extension of the bound that improves the order bounds by Beelen and by Duursma and Park. We include an exhaustive numerical comparison of the different bounds for 10168 two-point codes on the Suzuki curve of genus g=124 over the field of 32 elements. Keywords: algebraic geometric code, order bound, Suzuki curve.

Citations (324)

Summary

  • The paper extends the order bound for AG codes by implementing a refined partitioning strategy that improves the lower bound on minimum distance.
  • It demonstrates enhanced performance through numerical evaluations on 10,168 two-point codes on the Suzuki curve, achieving improvements of up to 6 units.
  • The study introduces efficient algorithms utilizing graph theory to reduce computational costs in calculating coset and two-point code distances.

An Extension of the Order Bound for AG Codes

The paper "An Extension of the Order Bound for AG Codes" by Iwan Duursma and Radoslav Kirov contributes to the field of algebraic geometric (AG) codes by advancing the theory of order bounds, particularly for the minimum distance of these codes. The primary focus of the paper is to extend the existing order bounds, thereby refining the lower bounds on the minimum distance of AG codes, notably improving the bounds proposed by Beelen and by Duursma and Park.

Summary

The authors set out to enhance the order bound, which generalizes the Feng-Rao bound, by introducing a more effective variant. The paper offers a comprehensive numerical evaluation of these bounds for 10,168 two-point codes on the Suzuki curve of genus 124 over the finite field with 32 elements, a setting that presents significant computational challenges.

The paper is structured as follows:

  1. Background and Introduction: The authors provide a concise introduction to AG codes, detailing the representation of divisor classes by base-point-free divisors.
  2. Theoretical Developments:
    • The paper establishes foundational AG code concepts, including the linear equivalence of divisors and the definition of geometric Goppa codes.
    • It discusses coset bounds and propositions related to dual codes, which are pivotal for understanding the minimum distance of the codes.
  3. Extension of Order Bounds:
    • The authors propose an extension to the order bound concept by employing a refined partitioning strategy that utilizes sequences of points. This is mathematically encapsulated by the introduction of divisor class calculations.
    • They demonstrate that this approach allows for more precise lower bounds for the minimum distance of codes.
  4. Numerical Evaluation:
    • The paper presents a set of numerical results illustrating the effectiveness of the extended order bound against existing methods, such as Goppa and Beelen bounds.
    • It notably uses the Suzuki curve configuration, relying on the semi-group and divisor class calculations to exhibit improved bounds.
  5. Efficiency and Algorithms:
    • The authors provide a methodological framework for efficiently computing the bounds using graph theory and computational algorithms. These methods contribute to computing coset distances and two-point code distances with increased precision and reduced computational costs.

Numerical Results and Implications

The numerical results indicate that the extended order bound consistently provides more robust estimates compared to traditional floor-type bounds across various codes in the Suzuki curve setting. Specifically, improvements of up to 6 in the minimum distance estimates were observed, demonstrating tangible advantages of this extension.

Theoretical and Practical Implications

From a theoretical perspective, this extension has implications for the fundamental theory of coding, particularly in constructing longer sequences of divisors which result in improved lower bounds for codes. Practically, these developments could lead to more efficient error-correcting codes, with potential applications in communication systems requiring high reliability.

Future Directions

Given the promising results, future research may focus on further improving the computational efficiency of the proposed algorithms. Additionally, exploring the extension's applicability to different curves or more complex configurations could provide broader insights into AG code performance.

In conclusion, the paper offers a substantial advancement in improving the minimum distance bounds of AG codes, reinforcing the utility of algebraic approaches in designing efficient coding systems. This work paves the way for future investigations into more advanced coding techniques underpinned by robust mathematical frameworks.