25 research outputs found

    Error Correcting Codes on Algebraic Surfaces

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    Error correcting codes are defined and important parameters for a code are explained. Parameters of new codes constructed on algebraic surfaces are studied. In particular, codes resulting from blowing up points in \proj^2 are briefly studied, then codes resulting from ruled surfaces are covered. Codes resulting from ruled surfaces over curves of genus 0 are completely analyzed, and some codes are discovered that are better than direct product Reed Solomon codes of similar length. Ruled surfaces over genus 1 curves are also studied, but not all classes are completely analyzed. However, in this case a family of codes are found that are comparable in performance to the direct product code of a Reed Solomon code and a Goppa code. Some further work is done on surfaces from higher genus curves, but there remains much work to be done in this direction to understand fully the resulting codes. Codes resulting from blowing points on surfaces are also studied, obtaining necessary parameters for constructing infinite families of such codes. Also included is a paper giving explicit formulas for curves with more \field{q}-rational points than were previously known for certain combinations of field size and genus. Some upper bounds are now known to be optimal from these examples.Comment: This is Chris Lomont's PhD thesis about error correcting codes from algebriac surface

    List Decoding of Algebraic Codes

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    Balanced Product Quantum Codes

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    This work provides the first explicit and non-random family of [[N,K,D]][[N,K,D]] LDPC quantum codes which encode KΘ(N45)K \in \Theta(N^\frac{4}{5}) logical qubits with distance DΩ(N35)D \in \Omega(N^\frac{3}{5}). The family is constructed by amalgamating classical codes and Ramanujan graphs via an operation called balanced product. Recently, Hastings-Haah-O'Donnell and Panteleev-Kalachev were the first to show that there exist families of LDPC quantum codes which break the polylog(N)N\operatorname{polylog}(N)\sqrt{N} distance barrier. However, their constructions are based on probabilistic arguments which only guarantee the code parameters with high probability whereas our bounds hold unconditionally. Further, balanced products allow for non-abelian twisting of the check matrices, leading to a construction of LDPC quantum codes that can be shown to have KΘ(N)K\in \Theta(N) and that we conjecture to have linear distance DΘ(N)D\in \Theta(N).Comment: 23 pages, 11 figure

    Bounds on codes from smooth toric threefolds with rank(pic(x)) = 2

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    In 1998, J. P. Hansen introduced the construction of an error-correcting code over a finite field Fq from a convex integral polytope in R2. Given a polytope P ⊂ R2, there is an associated toric variety XP , and Hansen used the cohomology and intersection theory of divisors on XP to determine explicit formulas for the dimension and minimum distance of the associated toric code CP . We begin by reviewing the basics of algebraic coding theory and toric varieties and discuss how these areas intertwine with discrete geometry. Our first results characterize certain polygons that generate and do not generate maximum distance separable (MDS) codes and Almost-MDS codes. In 2006, Little and Schenck gave formulas for the minimum distance of certain toric codes corresponding to smooth toric surfaces with rank(Pic(X)) = 2 and rank(Pic(X)) = 3. Additionally, they gave upper and lower bounds on the minimum distance of an arbitrary toric code CP by finding a subpolygon of P with a maximal, nontrivial Minkowski sum decomposition. Following this example, we give explicit formulas for the minimum distance of toric codes associated with two families of smooth toric threefolds with rank(Pic(X)) = 2, characterized by G. Ewald and A. Schmeinck in 1993. Lastly, we give explicit formulas for the dimension of a toric code generated from a Minkowski sum of a finite number of polytopes in R2 and R3 and a lower bound for the minimum distance
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