Characterization results on weighted minihypers and on linear codes meeting the G(r)iesmer bound

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The use of blocking sets in Galois geometries and in related research areas

Blocking sets play a central role in Galois geometries. Besides their intrinsic geometrical importance, the importance of blocking sets also arises from the use of blocking sets for the solution of many other geometrical problems, and problems in related research areas. This article focusses on these applications to motivate researchers to investigate blocking sets, and to motivate researchers to investigate the problems that can be solved by using blocking sets. By showing the many applications on blocking sets, we also wish to prove that researchers who improve results on blocking sets in fact open the door to improvements on the solution of many other problems

A characterisation result on a particular class of non-weighted minihypers

We present a characterisation of {epsilon(1)(q + 1)+ epsilon(0), epsilon(1); n, q}-minihypers, q square, q = p(h), p > 3 prime, h >= 2, q >= 1217, for epsilon(0) + epsilon(1) < q(7/12)/2 - q(1/4)/2. This improves a characterisation result of Ferret and Storme (Des Codes Cryptogr 25(2): 143- 162, 2002), involving more Baer subgeometries contained in the minihyper

Linear codes meeting the Griesmer bound, minihypers and geometric applications

Coding theory and Galois geometries are two research areas which greatly influence each other. In this talk, we focus on the link between linear codes meeting the Griesmer bound and minihypers in finite projective spaces. Minihypers are particular (multiple) blocking sets. We present characterization results on minihypers, leading to equivalent characterization results on linear codes meeting the Griesmer bound. Next to being interesting from a coding-theoretical point of view, minihypers also are interesting for geometrical applications. We present results on maximal partial μ-spreads in PG(N, q), (μ + 1)|(N + 1), on minimal μ-covers in PG(N, q), (μ + 1)|(N + 1), on (N − 1)-covers of Q + (2N + 1, q), on partial ovoids and on partial spreads of finite classical polar spaces, and on partial ovoids of generalized hexagons, following from results on minihypers

On the non-existence of a projective (75, 4,12, 5) set in PG(3, 7)

We show by a combination of theoretical argument and computer search that if a projective (75, 4, 12, 5) set in PG(3, 7) exists then its automorphism group must be trivial. This corresponds to the smallest open case of a coding problem posed by H. Ward in 1998, concerning the possible existence of an infinite family of projective two-weight codes meeting the Griesmer bound

New minimum distance bounds for linear codes over GF(5)

AbstractLet [n,k,d]q-codes be linear codes of length n, dimension k and minimum Hamming distance d over GF(q). In this paper, 32 new codes over GF(5) are constructed and the nonexistence of 51 codes is proved

Non-projective two-weight codes

It has been known since the 1970's that the difference of the non-zero weights of a projective $\mathbb{F}_q$-linear two-weight has to be a power of the characteristic of the underlying field. Here we study non-projective two-weight codes and e.g.\ show the same result under mild extra conditions. For small dimensions we give exhaustive enumerations of the feasible parameters in the binary case.Comment: 27 pages, 14 tables, appendix on parameters of projective two-weight codes adde