Bounds on the minimum distance of linear codes

Bounds on linear codes [168,8] over GF(4)

Construction

Construction of a linear code [168,8,115] over GF(4):
[1]:  [171, 162, 5] Constacyclic by w^2 Linear Code over GF(2^2)
     ConstaCyclicCode generated by x^9 + x^7 + w^2*x^5 + x^4 + w^2*x^2 + w^2 with shift constant w^2
[2]:  [171, 9, 117] Constacyclic by w Linear Code over GF(2^2)
     Dual of [1]
[3]:  [170, 8, 117] Linear Code over GF(2^2)
     Shortening of [2] at { 171 }
[4]:  [168, 8, 115] Linear Code over GF(2^2)
     Puncturing of [3] at { 169 .. 170 }

last modified: 2002-05-27

From Brouwer's table (as of 2007-02-13)

Lb(168,8) = 115 is found by shortening of:
Lb(169,9) = 115 is found by truncation of:
Lb(171,9) = 117 MTS

Ub(168,8) = 120 is found by considering truncation to:
Ub(167,8) = 119 Da1

References

MTS: Tatsuya Maruta, Mito Takenaka, Maori Shinohara & Yukie Shobara, Constructing new linear codes from pseudo-cyclic codes, pp. 292-298 in Proc. 9th International Workshop on Algebraic and Combinatorial Coding Theory(ACCT) in Kranevo, Bulgaria, 2004.

Notes All codes establishing the lower bounds were constructed using MAGMA. Upper bounds are taken from the tables of Andries E. Brouwer, with the exception of codes over GF(7) with n>50. For most of these codes, the upper bounds are rather weak. Upper bounds for codes over GF(7) with small dimension have been provided by Rumen Daskalov. Special thanks to John Cannon for his support in this project. A prototype version of MAGMA's code database over GF(2) was written by Tat Chan in 1999 and extended later that year by Damien Fisher. The current release version was developed by Greg White over the period 2001-2006. Thanks also to Allan Steel for his MAGMA support. My apologies to all authors that have contributed codes to this table for not giving specific credits. If you have found any code improving the bounds or some errors, please send me an e-mail: codes [at] codetables.de