In this paper, algebraic-geometric (ag) codes associated with the GGS maximal curve are investigated. The Weierstrass semigroup at all -rational points of the curve is determined;the Feng-Rao designed minimum distance...
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In this paper, algebraic-geometric (ag) codes associated with the GGS maximal curve are investigated. The Weierstrass semigroup at all -rational points of the curve is determined;the Feng-Rao designed minimum distance is computed for infinite families of such codes, as well as the automorphism group. As a result, some linear codes with better relative parameters with respect to one-point Hermitian codes are discovered. Classes of quantum and convolutional codes are provided relying on the constructed ag codes.
In this paper we investigate multi-point Algebraic-Geometric codes associated to the GK maximal curve, starting from a divisor which is invariant under a large automorphism group of the curve. We construct families of...
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In this paper we investigate multi-point Algebraic-Geometric codes associated to the GK maximal curve, starting from a divisor which is invariant under a large automorphism group of the curve. We construct families of codes with large automorphism groups.
We investigate algorithms for encoding of one-point algebraic geometry (ag) codes over certain plane curves called C-ab curves, as well as algorithms for inverting the encoding map, which we call "unencoding"...
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We investigate algorithms for encoding of one-point algebraic geometry (ag) codes over certain plane curves called C-ab curves, as well as algorithms for inverting the encoding map, which we call "unencoding". Some C-ab curves have many points or are even maximal, e.g. the Hermitian curve. Our encoding resp. unencoding algorithms have complexity (O) over tilde (n(3/2)) resp. (O) over tilde (qn) for ag codes over any C-ab curve satisfying very mild assumptions, where n is the code length and q the base field size, and (O) over tilde ignores constants and logarithmic factors in the estimate. For codes over curves whose evaluation points lie on a grid-like structure, for example the Hermitian curve and norm-trace curves, we show that our algorithms have quasi-linear time complexity (O) over tilde (n) for both operations. For infinite families of curves whose number of points is a constant factor away from the Hasse-Weil bound, our encoding and unencoding algorithms have complexities (O) over tilde (n(5/4)) and (O) over tilde (n(3/2)) respectively.
A sharp upper bound for the maximum integer not belonging to an ideal of a numerical semigroup is given and the ideals attaining this bound are characterized. Then, the result is used, through the so-called Feng-Rao n...
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A sharp upper bound for the maximum integer not belonging to an ideal of a numerical semigroup is given and the ideals attaining this bound are characterized. Then, the result is used, through the so-called Feng-Rao numbers, to bound the generalized Hamming weights of algebraic-geometry codes. This is further developed for Hermitian codes and the codes on one of the Garcia-Stichtenoth towers, as well as for some more general families.
Consider a complete flagcode = C-0 2g + 2 rational points is isometry-dual if and only if the last code C-n in the flag is defined with functions of pole order at most n + 2g - 1. Using a different approach, we exten...
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Consider a complete flagag code = C-0 < C-1 < center dot center dot center dot < C-n = F-n of one-point ag codes of length n over the finite field F. The codes are defined by evaluating functions with poles at a given point Q in points P-1, ... , P-n distinct from Q. A flag has the isometry-dual property if the given flag and the corresponding dual flag are the same up to isometry. For several curves, including the projective line, Hermitian curves, Suzuki curves, Ree curves, and the Klein curve over the field of eight elements, the maximal flag, obtained by evaluation in all rational points different from the point Q, is self-dual. More generally, we ask whether a flag obtained by evaluation in a proper subset of rational points is isometry-dual. In Geil et al. (2011) it is shown, for a curve of genus g, that a flag of one-point ag codes defined with a subset of n > 2g + 2 rational points is isometry-dual if and only if the last code C-n in the flag is defined with functions of pole order at most n + 2g - 1. Using a different approach, we extend this characterization to all subsets of size n >= 2g + 2. Moreover we show that this is best possible by giving examples of isometry-dual flags with n = 2g + 1 such that Cn is generated by functions of pole order at most n + 2g - 2. We also prove a necessary condition, formulated in terms of maximum sparse ideals of the Weierstrass semigroup of Q, under which a flag of punctured one-point ag codes inherits the isometry-dual property from the original unpunctured flag.
A flag of linear codes C0 ( C1 ( \cdot \cdot \cdot ( Cs is said to have the isometry-dual property if there exists a vector \bfx \in (Fqast \)n such that Ci = \bfx \cdot C\bot s - i, where Cibot \denotes the dual code...
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A flag of linear codes C0 ( C1 ( \cdot \cdot \cdot ( Cs is said to have the isometry-dual property if there exists a vector \bfx \in (Fqast \)n such that Ci = \bfx \cdot C\bot s - i, where Cibot \denotes the dual code of the code Ci. We extend our previous results in [M. Bras-Amoro'\s, A. S. Castellanos, and L. Quoos, IEEE Trans. Inform. Theory, 68 (2022), pp. 828--838] of flags of algebraic geometry two-point codes over a function field F to flags of (t + 1)-point codes C\scrL (D, a0P + \sum ti=1 \beta iQi) ( C\scrL (D, a1P + \sum ti=1 \beta iQi)) ( \cdot \cdot \cdot ( C\scrL (D,asP +\sum t i=1 \beta iQi) for any tuple of integers \beta 1, ... ,\beta t and for an increasing sequence of integers a0, . . . , as, just provided that n \geq 2g + 2, where g is the genus of F. We apply the obtained results to the broad class of Kummer extensions defined by affine equations of the form ym = f (x) for f(x), a separable polynomial of degree r, where gcd(r, m) = 1. In particular, we obtain necessary and sufficient conditions on m and \beta i's such that the flag has the isometry-dual property.
In this paper, we derive general bounds for the number of rational points on a cubic surface defined over F-q, which constitute an extension of a result due to Weil. Exploiting these bounds, we are able to give a comp...
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In this paper, we derive general bounds for the number of rational points on a cubic surface defined over F-q, which constitute an extension of a result due to Weil. Exploiting these bounds, we are able to give a complete characterization of the intersections between the Norm-Trace curve over F-q3 and the curves of the form y = ax(3) + bx(2) + cx + d, generalizing a previous result by Bonini and Sala and providing more detailed information about the weight spectrum of one-point ag codes arising from such curve.
We investigate several types of linear codes constructed from two families of maximal curves over finite fields recently constructed by Skabelund as cyclic covers of the Suzuki and Ree curves. Plane models for such cu...
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We investigate several types of linear codes constructed from two families of maximal curves over finite fields recently constructed by Skabelund as cyclic covers of the Suzuki and Ree curves. Plane models for such curves are provided, and the Weierstrass semigroup at an F-q-rational point is shown to be symmetric.
A flag of codes C-0 not subset of C-1 not subset of center dot center dot center dot not subset of C-s not subset of F-q(n) is said to satisfy the isometry-dual property if there exists x is an element of (F-q*)(n) su...
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A flag of codes C-0 not subset of C-1 not subset of center dot center dot center dot not subset of C-s not subset of F-q(n) is said to satisfy the isometry-dual property if there exists x is an element of (F-q*)(n) such that the code C-i is x-isometric to the dual code C-s-i(perpendicular to) for all i = 0, ..., s. For P and Q rational places in a function field F, we investigate the existence of isometry-dual flags of codes in the families of two-point algebraic geometry codes C-L(D, a(0)P + bQ) not subset of C-L(D, a(1)P + bQ) not subset of center dot center dot center dot not subset of C-L(D, a(s)P + bQ), where the divisor D is the sum of pairwise different rational places of F and P, Q are not in supp(D). We characterize those sequences in terms of b for general function fields. We then apply the result to the broad class of Kummer extensions F defined by affine equations of the form y(m) = f(x), for f(x) a separable polynomial of degree r, where gcd(r, m) = 1. For P the rational place at infinity and Q the rational place associated to one of the roots of f(x), and for D an Aut(F/F-q)-invariant sum of rational places of F, such that P, Q is not an element of supp D, it is shown that the flag of two-point algebraic geometry codes has the isometry-dual property if and only if m divides 2b + 1. At the end we illustrate our results by applying them to two-point codes over several well know function fields.
We determine the Weierstrass semigroup H(P infinity,P1, horizontal ellipsis ,Pm) at several rational points on the maximal curves which cannot be covered by the Hermitian curve introduced in Tafazolian et al. (J Pure ...
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We determine the Weierstrass semigroup H(P infinity,P1, horizontal ellipsis ,Pm) at several rational points on the maximal curves which cannot be covered by the Hermitian curve introduced in Tafazolian et al. (J Pure Appl Algebra 220(3):1122-1132, 2016). Furthermore, we present some conditions to find pure gaps. We use this semigroup to obtain ag codes with better relative parameters than comparable one-point ag codes arising from these curves.
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