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On Extremal Binary Doubly-Even Self-Dual Codes of Length 88*

Yorgova, Radinka, At, Nuray (2009)

Serdica Journal of Computing

In this paper we present 35 new extremal binary self-dual doubly-even codes of length 88. Their inequivalence is established by invariants. Moreover, a construction of a binary self-dual [88, 44, 16] code, having an automorphism of order 21, is given.*This work was partly supported by the Norwegian Government Scholarship.

On sets of vectors of a finite vector space in which every subset of basis size is a basis

Simeon Ball (2012)

Journal of the European Mathematical Society

It is shown that the maximum size of a set S of vectors of a k -dimensional vector space over 𝔽 q , with the property that every subset of size k is a basis, is at most q + 1 , if k p , and at most q + k p , if q k p + 1 4 , where q = p k and p is prime. Moreover, for k p , the sets S of maximum size are classified, generalising Beniamino Segre’s “arc is a conic” theorem. These results have various implications. One such implication is that a k × ( p + 2 ) matrix, with k p and entries from 𝔽 p , has k columns which are linearly dependent. Another is...

On some Optimal (n,t,1,2) and (n,t,1,3) Super Imposed Codes

Manev, Mladen (2009)

Serdica Journal of Computing

Partially supported by the Technical University of Gabrovo under Grant C-801/2008One of the main problems in the theory of superimposed codes is to find the minimum length N for which an (N, T,w, r) superimposed code exists for given values of T , w and r. Let N(T,w, r) be the minimum length N for which an (N, T,w, r) superimposed code exists. The (N, T,w, r) superimposed code is called optimal when N = N(T,w, r). The values of N(T, 1, 2) are known for T ≤ 12 and the values of N(T, 1, 3) are known for...

On the construction of dense lattices with a given automorphisms group

Philippe Gaborit, Gilles Zémor (2007)

Annales de l’institut Fourier

We consider the problem of constructing dense lattices in n with a given non trivial automorphisms group. We exhibit a family of such lattices of density at least c n 2 - n , which matches, up to a multiplicative constant, the best known density of a lattice packing. For an infinite sequence of dimensions n , we exhibit a finite set of lattices that come with an automorphisms group of size n , and a constant proportion of which achieves the aforementioned lower bound on the largest packing density. The algorithmic...

On the structure of linear recurrent error-control codes

Michel Fliess (2002)

ESAIM: Control, Optimisation and Calculus of Variations

We are extending to linear recurrent codes, i.e., to time-varying convolutional codes, most of the classic structural properties of fixed convolutional codes. We are also proposing a new connection between fixed convolutional codes and linear block codes. These results are obtained thanks to a module-theoretic framework which has been previously developed for linear control.

On the structure of linear recurrent error-control codes

Michel Fliess (2010)

ESAIM: Control, Optimisation and Calculus of Variations

We are extending to linear recurrent codes, i.e., to time-varying convolutional codes, most of the classic structural properties of fixed convolutional codes. We are also proposing a new connection between fixed convolutional codes and linear block codes. These results are obtained thanks to a module-theoretic framework which has been previously developed for linear control.

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