2 problems

Let $(A,B)$ be the $(v/2)$-decomposition of a periodic Golay pair $\operatorname{PG}(v)$ with row sums $a$ and $b$. Equivalence is taken in the sense used for these decompositions.…

A Hadamard matrix of 2N-type is a Hadamard matrix of order $2v$ of the block form … where $A$ and $B$ are negacyclic blocks. 2N-type existence conjecture. For each even integer…