Combinatorics, Coding and Security Group (CCSG)
 The Combinatorics, Coding and Security Group (CCSG) is a research group in the Department of Information and Communications Engineering (DEIC) at the Universitat Autònoma de Barcelona (UAB). Group CCSG has been uninterruptedly working since 1987 in several projects and research activities on Information Theory, Communications, Coding Theory, Source Coding, Cryptography, Electronic Voting, Network Coding.
2017-03-18
14:57
 6 p, 110.7 KB About non equivalent completely regular codes with identical intersection array / Rifà i Coma, Josep (Universitat Autònoma de Barcelona. Grup de Recerca Codificació, Compressió i Seguretat (CCS)) ; Zinoviev, Victor We obtain several classes of completely regular codes with different parameters, but identical intersection array. Given a prime power q and any two natural numbers a, b, we construct completely transitive codes over different fields with covering radius ρ = min{a, b} and identical intersection array, specifically, we construct one code over F_{q^r} for each divisor r of a or b. [...] 2017 - 10.1016/j.endm.2017.02.030 Electronic Notes in Discrete Mathematics, Vol. 57 (2017) , p. 181-186
2016-12-19
16:01
 6 p, 163.1 KB Completely regular codes with different parameters and the same intersection arrays / Rifà i Coma, Josep (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Zinoviev, V. A. (Kharkevich Institute for Problems of Information Transmission) 26. 1. 17 SUSANA - Demano informació sobre les polítiques de copyright via correu electrònic a l'ACCT 2016. Reclamat el 14. 2. 2017. We obtain several classes of completely regular codes with different parameters, but identical intersection array. Given a prime power q and any two natural numbers a, b, we construct completely transitive codes over different fields with covering radius ρ = min{a, b} and identical intersection array, specifically, we construct one code over Fqʳ for each divisor r of a or b. [...] 2016 International Workshop on Algebraic and Combinatorial Coding Theory. Albena, Bulgaria, 15th : 2016
2016-10-24
15:51
 36.5 KB Quasi-cyclic codes as cyclic codes over a family of local rings / Dougherty, Steven T. (University of Scranton. Department of Mathematics) ; Fernández-Córdoba, Cristina (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Ten-Valls, Roger (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) 2016 - 10.1016/j.ffa.2016.04.002 Finite fields and their applications, Vol. 40 (July 2016) , p. 138-149
2016-10-24
15:44
 Kernels and ranks of cyclic and negacyclic quaternary codes / Dougherty, Steven T. (University of Scranton. Department of Mathematics) ; Fernández-Córdoba, Cristina (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) We study the rank and kernel of Z4 cyclic codes of odd length n and give bounds on the size of the kernel and the rank. Given that a cyclic code of odd length is of the form C = , where fgh = x^n − 1, we show that <2f> ⊆ K(C) ⊆ C and C ⊆ R(C) ⊆ where K(C) is the preimage of the binary kernel and R(C) is the preimage of the space generated by the image of C. [...] 2016 - 10.1007/s10623-015-0163-6 Designs codes and cryptography, Vol. 81, Issue 2 (Nov. 2016) , p. 347-364
2016-10-18
12:55
 5 p, 2.0 MB PD-sets for Z₄-linear codes : Hadamard and Kerdock codes / Barrolleta, Roland D. (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Villanueva, M. (Mercè) (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) Permutation decoding is a technique that strongly depends on the existence of a special subset, called PD-set, of the permutation automorphism group of a code. In this paper, a general criterion to obtain s-PD-sets of size s+1, which enable correction up to s errors, for Z₄-linear codes is provided. [...] 2016 - 10.1109/ISIT.2016.7541512 2016 IEEE International Symposium on Information Theory (ISIT), (Aug. 2016) , p. 1317-1321
2016-10-18
12:33
 11 p, 301.2 KB Linear and cyclic codes over direct product of finite chain rings / Borges, J. (Joaquim) (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Fernández-Córdoba, Cristina (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Ten-Valls, Roger (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) We introduce a new type of linear and cyclic codes. These codes are defined over a direct product of two finite chain rings. The definition of these codes as certain submodules of the direct product of copies of these rings is given and the cyclic property is defined. [...] 2016 16th International Conference on Computational and Mathematical Methods in Science and Engineering (CMMSE 2016). Rota, Cádiz, : 2016
2016-10-18
12:27
 Comparing decoding methods for quaternary linear codes / Barrolleta, Roland D. (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Pujol Capdevila, Jaume (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Villanueva, M. (Mercè) (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) Permutation decoding is a technique which involves finding a subset S, called PD-set, of the permutation automorphism group of a code C. Constructions of small PD-sets for partial decoding for two families of Z₄-linear codes (Hadamard and Kerdock) are given. [...] 2016 - 10.1016/j.endm.2016.09.049 Electronic notes in discrete mathematics, Vol. 54 (Oct. 2016) , p. 283-288
2016-10-18
11:53
 Construction and classification of Z₂s-linear Hadamard codes / Fernández-Córdoba, Cristina (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Vela, C. (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Villanueva, M. (Mercè) (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) The Z₂s-additive and Z₂Z₄-additive codes are subgroups of Z₂s^n and Z₂^α × Z₄^β, respectively. Both families can be seen as generalizations of linear codes over Z₂ and Z₄. A Z₂s-linear (resp. [...] 2016 - 10.1016/j.endm.2016.09.043 Electronic notes in discrete mathematics, Vol. 54 (Oct. 2016) , p. 247-252
2016-10-18
11:36
 About some Hadamard full propelinear (2t,2,2)-codes : Rank and Kernel / Bailera, Ivan (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Borges, J. (Joaquim) (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Rifà i Coma, Josep (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) A new subclass of Hadamard full propelinear codes is introduced in this article. We define the HFP(2t,2,2)-codes as codes with a group structure isomorphic to C₂t × C₂^2. Concepts such as rank and dimension of the kernel are studied, and bounds for them are established. [...] 2016 - 10.1016/j.endm.2016.09.055 Electronic notes in discrete mathematics, Vol. 54 (Oct. 2016) , p. 319-324
2016-01-11
12:00
 8 p, 1010.8 KB Ranks and kernels of codes from generalized Hadamard matrices / Dougherty, Steven T. (University of Scranton. Department of Mathematics) ; Rifà i Coma, Josep (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) ; Villanueva, M. (Mercè) (Universitat Autònoma de Barcelona. Departament d'Enginyeria de la Informació i de les Comunicacions) The ranks and kernels of generalized Hadamard matrices are studied. It is proved that any generalized Hadamard matrix H(q, λ) over Fq , q > 3, or q = 3 and gcd(3, λ) ≠ 1, generates a self-orthogonal code. [...] 2016 - 10.1109/TIT.2015.2509061 IEEE transactions on information theory, Vol. 62 No. 2 (Feb. 2016) , p. 687-694