A multi-dimensional approach to the construction and enumeration of Golay complementary sequences

We argue that a Golay complementary sequence is naturally viewed as a projection of a multi-dimensional Golay array. We present a three-stage process for constructing and enumerating Golay array and sequence pairs:

1.

construct suitable Golay array pairs from lower-dimensional Golay array pairs;

2.

apply transformations to these Golay array pairs to generate a larger set of Golay array pairs; and

3.

take projections of the resulting Golay array pairs to lower dimensions.

This process greatly simplifies previous approaches, by separating the construction of Golay arrays from the enumeration of all possible projections of these arrays to lower dimensions.We use this process to construct and enumerate all h²-phase Golay sequences of length m² obtainable under any known method, including all 4-phase Golay sequences obtainable from the length 16 examples given in 2005 by Li and Chu [Y. Li, W.B. Chu, More Golay sequences, IEEE Trans. Inform. Theory 51 (2005) 1141-1145].     

Golay complementary array pairs

Constructions and nonexistence conditions for multi-dimensional Golay complementary array pairs are reviewed. A construction for a d-dimensional Golay array pair from a (d + 1)-dimensional Golay array pair is given. This is used to explain and expand previously known constructive and nonexistence results in the binary case.      

Quaternary Golay sequence pairs II: odd length

A 4-phase Golay sequence pair of length s ?? 5 (mod 8) is constructed from a Barker sequence of the same length whose even-indexed elements are prescribed. This explains the origin of the 4-phase Golay seed pairs of length 5 and 13. The construction cannot produce new 4-phase Golay sequence pairs, because there are no Barker sequences of odd length greater than 13. A partial converse to the construction is given, under the assumption of additional structure on the 4-phase Golay sequence pair of length s ?? 5 (mod 8).     

Walsh spectrum and nega spectrum of complementary arrays

Designs, Codes and Cryptography - It has been shown that all the known binary Golay complementary sequences of length $$2^m$$ can be obtained by a single binary Golay complementary array of...     

Constructing self-orthogonal and Hermitian self-orthogonal codes via weighing matrices and orbit matrices

We define the notion of an orbit matrix with respect to standard weighing matrices, and with respect to types of weighing matrices with entries in a finite field. In the latter case we primarily restrict our attention the fields of order 2, 3 and 4. We construct self-orthogonal and Hermitian self-orthogonal linear codes over finite fields from these types of weighing matrices and their orbit matrices respectively. We demonstrate that this approach applies to several combinatorial structures such as Hadamard matrices and balanced generalized weighing matrices. As a case study we construct self-orthogonal codes from some weighing matrices belonging to some well known infinite families, such as the Paley conference matrices, and weighing matrices constructed from ternary periodic Golay pairs.     

Quaternary Golay sequence pairs I: even length

The origin of all 4-phase Golay sequences and Golay sequence pairs of even length at most 26 is explained. The principal techniques are the three-stage construction of Fiedler, Jedwab and Parker involving multi-dimensional Golay arrays, and a ??sum?Cdifference?? construction that modifies a result due to Eliahou, Kervaire and Saffari. The existence of 4-phase seed pairs of lengths 3, 5, 11, and 13 is assumed; their origin is considered in (Gibson and Jedwab, Des Codes Cryptogr, 2010).     

Modular andp-adic cyclic codes

This paper presents some basic theorems giving the structure of cyclic codes of lengthn over the ring of integers modulop ^a and over thep-adic numbers, wherep is a prime not dividingn. An especially interesting example is the 2-adic cyclic code of length 7 with generator polynomialX ³ +X ² +(–1)X–1, where satisfies ² - + 2 = 0. This is the 2-adic generalization of both the binary Hamming code and the quaternary octacode (the latter being equivalent to the Nordstrom-Robinson code). Other examples include the 2-adic Golay code of length 24 and the 3-adic Golay code of length 12.     

Unrestricted codes with the golay parameters are unique

The paper contains a proof of the uniqueness of both binary and ternary Golay codes, without assumption of linearity. Similar results are obtained about the extended and expurgated Golay codes. The method consists in proving the linearity, which, according to Pless' results, implies the uniqueness.     

The poset structures admitting the extended binary Golay code to be a perfect code

Brualdi et al. [Codes with a poset metric, Discrete Math. 147 (1995) 57-72] introduced the concept of poset codes, and gave an example of poset structure which admits the extended binary Golay code to be a 4-error-correcting perfect P-code. In this paper we classify all of the poset structures which admit the extended binary Golay code to be a 4-error-correcting perfect P-code, and show that there are no posets which admit the extended binary Golay code to be a 5-error-correcting perfect P-code.     

5-Designs from the lifted Golay code over Z4 via an Assmus–Mattson type approach

Recently, Harada showed that the codewords of Hamming weight 10 in the lifted quaternary Golay code form a 5-design. The codewords of Hamming weight 12 in the lifted Golay code are of two symmetric weight enumerator (swe) types. The codewords of each of the two swe types were also shown by Harada to form a 5-design. While Harada's results were obtained via computer search, a subsequent analytical proof of these results appears in a paper by Bonnecaze, Rains and Sole. Here we provide an alternative analytical proof, using an Assmus–Mattson type approach, that the codewords of Hamming weight 12 in the lifted Golay code of each symmetric weight enumerator type, form a 5-design.Also included in the paper is the weight hierarchy of the lifted Golay code. The generalized Hamming weights are used to distinguish between simple 5-designs and those with repeated blocks.     

Golay code and random packing

Summary A random sequential packing by Hamming distance is applied to study Golay code. The probability of getting Golay code is estimated by computer simulation. A histogram of number of packed points is given to show the existence of several remarkable clusters. The Institute of Statistical Mathematics     

A construction of binary Golay sequence pairs from odd‐length Barker sequences

Binary Golay sequence pairs exist for lengths 2, 10 and 26 and, by Turyn's product construction, for all lengths of the form 2^a10^b26^c where a, b, c are non‐negative integers. Computer search has shown that all inequivalent binary Golay sequence pairs of length less than 100 can be constructed from five “seed” pairs, of length 2, 10, 10, 20 and 26. We give the first complete explanation of the origin of the length 26 binary Golay seed pair, involving a Barker sequence of length 13 and a related Barker sequence of length 11. This is the special case m=1 of a general construction for a length 16m+10 binary Golay pair from a related pair of Barker sequences of length 8m+5 and 8m+3, for integer m≥0. In the case m=0, we obtain an alternative explanation of the origin of one of the length 10 binary Golay seed pairs. The construction cannot produce binary Golay sequence pairs for m>1, having length greater than 26, because there are no Barker sequences of odd length greater than 13. © 2009 Wiley Periodicals, Inc. J Combin Designs 17: 478–491, 2009     

A construction for Hadamard matrices

Let 2ⁿm be the order of an Hadamard matrix. Using block Golay sequences, a class of Hadamard matrices of order (r+4ⁿ+1)4ⁿ⁺¹m² is constructed, where r is the length of a Golay sequence.     

Ternary Covering Codes Derived from BCH Codes

It is shown how ternary BCH codes can be lengthened to get linear codes with covering radius 2. The family obtained has the ternary Golay code as its first code, contains codes with record-breaking parameters, and has a good asymptotic behavior. The ternary Golay code is further used to obtain short proofs for the best known upper bounds for the football pool problem for 11 and 12 matches.     

On equivalence of negaperiodic Golay pairs

Associated pairs as defined by Ito (J Algebra 234:651–663, 2000) are pairs of binary sequence of length 2t satisfying certain autocorrelation properties that may be used to construct Hadamard matrices of order 4t. More recently, Balonin and Dokovi? (Inf Control Syst 5:2–17, 2015) use the term negaperiodic Golay pairs. We define extended negaperiodic Golay pairs and prove a one-to-one correspondence with central relative (4t, 2, 4t, 2t)-difference sets in dicyclic groups of order 8t. We present a new approach for computing negaperiodic Golay pairs up to equivalence, and determine conditions where equivalent pairs correspond to equivalent Hadamard matrices. We complete an enumeration of negaperiodic Golay pairs of length 2t for \(1 \le t \le 10\), and sort them into equivalence classes. Some structural properties of negaperiodic Golay pairs are derived.     

Spectral Characterizations of Some Distance-Regular Graphs

When can one see from the spectrum of a graph whether it is distance-regular or not? We give some new results for when this is the case. As a consequence we find (among others) that the following distance-regular graphs are uniquely determined by their spectrum: The collinearity graphs of the generalized octagons of order (2,1), (3,1) and (4,1), the Biggs-Smith graph, the M ₂₂ graph, and the coset graphs of the doubly truncated binary Golay code and the extended ternary Golay code.     

A construction of mutually disjoint Steiner systems from isomorphic Golay codes

It is well known that the extended binary Golay [24,12,8] code yields 5-designs. In particular, the supports of all the weight 8 codewords in the code form a Steiner system S(5,8,24). In this paper, we give a construction of mutually disjoint Steiner systems S(5,8,24) by constructing isomorphic Golay codes. As a consequence, we show that there exists at least 22 mutually disjoint Steiner systems S(5,8,24). Finally, we prove that there exists at least 46 mutually disjoint 5-(48,12,8) designs from the extended binary quadratic residue [48,24,12] code.     

Approximation of almost periodic functions by periodic ones

It is not the purpose of this paper to construct approximations but to establish a class of almost periodic functions which can be approximated, with an arbitrarily prescribed accuracy, by continuous periodic functions uniformly on =(+).     

The toric geometry of some Niemeier lattices

The paper presents examples of complete singular toric varieties associated to the Niemeier lattices. The singularities and automorphisms of these varieties are seen to be closely related to the Golay codes.     

A new construction of the binary golay code (24, 12, 8) using a group algebra over a finite field

We construct the binary Golay code (24, 12, 8) obtained as the binary image, relative to a certain basis, of a principal ideal in a group algebra over a finite field.