Coding theory / 00

Roadmap to AG Codes

This article is the coverage audit and reading map for the companion series to Algebraic geometric codes on curves and surfaces.

The source text has a compact structure: elementary coding theory, algebraic-geometric codes on curves, decoding algorithms, scheme-theoretic preparation for higher-dimensional varieties, surface codes, and ruled surface codes. The purpose of this reorganized collection is to make that path readable as a sequence of lecture notes. The articles are a companion designed to supply the missing connective tissue, computations, notation, and examples.

Source coverage audit
PDF part Main mathematical content Companion articles
IntroductionGoppa idea, TVZ improvement, passage from curves to surfaces00, 06, 18
Chapter 1Basic codes, Singleton/Hamming/Gilbert bounds, Shannon motivation, duality, syndrome decoding; Plotkin added as standard high-distance context01, 02
Chapter 2.1Evaluation AG codes on curves and Riemann-Roch parameter bounds03, 04
Chapter 2.2Dual AG codes, residues, canonical divisors, duality theorem05
Chapter 2.3Rational points, Hasse-Weil, Ihara function, TVZ bound06
Chapter 3.1Skorobogatov-Vladut algorithm07
Chapter 3.2, 3.4, 3.5Cubic curve and Klein quartic computations09
Chapter 3.3Duursma majority voting algorithm08
Chapter 4.1Sheaves, locally free sheaves, coherent sheaves, twists10
Chapter 4.2Divisors on varieties, Picard group, line bundles11
Chapter 4.3Germ-map codes on varieties11
Chapter 5.1-5.3Ample divisors, genus, cohomology, intersections, surface Riemann-Roch12
Chapter 5.4Parameter bounds for surface codes, Hansen and Zarzar-Voloch context13
Chapter 6.1-6.3Projective bundles, ruled surface geometry, general ruled-surface parameters14, 15
Chapter 6.4-6.6Rational ruled surfaces and dimension computations15, 16
Chapter 6.7Ruled surfaces over elliptic curves, Atiyah classification, degree 0 and 1 cases17
Chapter 6.8Open problems and research directions18

Notation used throughout

The finite field is \(\mathbb F_q\). A linear code has parameters \([n,k,d]_q\). A curve is smooth, projective, geometrically integral, and defined over \(\mathbb F_q\) unless explicitly stated otherwise. For a divisor \(G\) on a curve, \(L(G)=\{f:(f)+G\ge0\}\cup\{0\}\). Evaluation codes are denoted \(C_L(D,G)\) and differential codes \(C_\Omega(D,G)\), with \(D=P_1+\cdots+P_n\) disjoint from \(G\).

Reading order

The first two articles reconstruct Chapter 1. The finite-field and polynomial-code bridge is made explicit through the Singleton-tight polynomial example, the syndrome examples over finite fields, and the Reed-Solomon realization on \(\mathbb P^1\) before the general curve construction. Articles 03-06 give the curve theory of Chapter 2. Articles 07-09 separate the decoding chapter into locators, majority voting, and worked examples. Articles 10-11 supply the scheme and sheaf language used in Chapter 4. Articles 12-13 cover surfaces. Articles 14-17 cover ruled surfaces. Article 18 records the open problems and the research map.

01. Coding Theory Foundations
metrics, bounds, asymptotics
02. Linear Codes and Syndromes
duality and decoding
03. Curves and Riemann-Roch
divisors and spaces
04. AG Evaluation Codes
dimension and distance
05. Residue Codes
differentials and duality
06. Rational Points and TVZ
asymptotic curve codes
07. SV Algorithm
error locators
08. Duursma Voting
syndrome completion
09. Worked Decoding
cubic and Klein quartic
10. Sheaves and Twists
Chapter 4 language
12. Surface Geometry
intersection and RR
14. Ruled Geometry
projective bundles
15. Ruled Parameters
rational ruled surfaces
16. Ruled Dimensions
symmetric powers
17. Elliptic Ruled Codes
Atiyah and Lomont
18. Open Problems
research map