On Hadamard Groups IV

Let (2n) be the set of {−1, 1} sequences of length 2n. Then the purpose of the present paper is to introduce the concept of L-structure to elements of (2n) and to rewrite the necessary and sufficient conditions for a pair of elements of (2n) to be associated in terms of L-structure so that the condition becomes more visible. We hope that this makes it a little easier to construct an associated pair.