Chapter 5
Codes, Arrangements and Matroids
Relinde Jurrius* and Ruud Pellikaan†
Eindhoven University of TechnologyDepartment of Mathematics and Computer Science, Coding and CryptoP.O. Box 513, NL-5600 MB Eindhoven, The Netherlands*
[email protected] †[email protected] This chapter treats error-correcting codes and their weight enumerator as the center of several closely related topics such as arrangements of hyperplanes, graph theory, matroids, posets and geometric lattices and their characteristic, chromatic, Tutte, Möbius and coboundary polynomial, respectively. Their interrelations and many examples and counterexamples are given. It is concluded with a section with references to the literature for further reading and open questions.
AMS classification: 05B35, 05C31, 06A07, 14N20, 94B27, 94B70, 94C15
Contents
5.1 Introduction
5.2 Error-correcting codes
5.2.1 Codes and Hamming distance
5.2.2 Linear codes
5.2.3 Generator matrix
5.2.4 Parity check matrix
5.2.5 Inner product and dual codes
5.2.6 The Hamming and simplex codes
5.2.7 Singleton bound and MDS codes
5.3 Weight enumerators and error probability
5.3.1 Weight spectrum
5.3.2 The decoding problem
5.3.3 The q-ary symmetric channel
5.3.4 Error probability
5.4 Codes, projective systems and arrangements
5.5 The extended and generalized weight enumerator
5.5.1 Generalized weight enumerators
5.5.2 Extended weight enumerator
5.5.3 Puncturing and shortening of codes
5.5.4 Connections
5.5.5 MDS-codes
5.6 Matroids and codes
5.6.1 Matroids
5.6.2 Graphs, codes and matroids
5.6.3 The weight enumerator and the Tutte polynomial
5.6.4 Deletion and contraction of matroids
5.6.5 MacWilliams type property for duality
5.7 Posets and lattices
5.7.1 Posets, the Möbius function and lattices
5.7.2 Geometric lattices
5.7.3 Geometric lattices and matroids
5.8 The characteristic polynomial
5.8.1 The characteristic and coboundary polynomial
5.8.2 The Möbius polynomial and Whitney numbers
5.8.3 Minimal codewords and subcodes
5.8.4 The characteristic polynomial of an arrangement
5.8.5 The characteristic polynomial of a code
5.8.6 Examples and counte...