Bounds on the minimum distance of linear codes
Bounds on linear codes [56,22] over GF(4)
lower bound:  20 
upper bound:  26 
Construction
Construction type: Seneviratne
Construction of a linear code [56,22,20] over GF(4):
[1]: [56, 22, 20] Quasicyclic of degree 2 Linear Code over GF(2^2)
QuasiCyclicCode of length 56 with generating polynomials: x^27 + x^25 + x^22 + x^12, a^2*x^27 + x^26 + a^2*x^25 + a^2*x^24 + a^2*x^23 + x^22 + a^2*x^21 +
a^2*x^19 + a^2*x^18 + a^2*x^17 + a^2*x^15 + a*x^13 + a^2*x^12 + a^2*x^11 + a*x^10 + a*x^9 + a^2*x^8 + x^7 + a^2*x^5 + a*x^4 + x^3 + a*x^2 + a^2*x + a
last modified: 20200717
From Brouwer's table (as of 20070213)
Lb(56,22) = 19 is found by shortening of:
Lb(61,27) = 19 is found by truncation of:
Lb(65,27) = 23 BCH
Ub(56,22) = 26 follows by a onestep Griesmer bound from:
Ub(29,21) = 6 is found by considering shortening to:
Ub(18,10) = 6 is found by construction B:
[consider deleting the (at most) 8 coordinates of a word in the dual]
References
BCH:
T. Kasami & N. Tokura, Some remarks on BCH bounds and minimum weights of
binary primitive BCH codes, IEEE Trans. Inform. Theory IT15 (May
1969) 408413.
Or: a BCH code.
Notes
 All codes establishing the lower bounds where constructed using
MAGMA.
 Upper bounds are taking 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 20012006.
 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 email:
codes [at] codetables.de

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Last change: 30.12.2011