8 problems

A complex Hadamard matrix of dimension $N$ is a matrix whose entries have modulus one and whose rows are pairwise orthogonal. Two such matrices are equivalent if one can be obtaine…

Classification conjecture. There are only two full-dimensional thick te-interlaces, up to resigning or permuting rows and columns:

For matrices $A$ and $B$ of size $m\times n$, say that they are congruent if there are invertible square matrices $U$ and $V$ of orders $m$ and $n$, respectively, such that $UA=BV$…

Let $F_7$ be the Fourier matrix of order $7$, and let $P_7^q$ denote the displayed Petrescu family, with $q\in\mathbb T$. A regular complex Hadamard matrix is one whose row scalar…

Let $S_6^{(0)}$ be the isolated $6\times 6$ Hadamard matrix, and let Szöllősi's generic four-parameter family be the family of order-six Hadamard matrices constructed by his genera…

Let … and consider embedding $E$ as the upper-left $3\times3$ block of a complex Hadamard matrix of order $6$, with complementary $3\times3$ blocks $B$ and $C$. Two matrices are eq…

A complex Hadamard matrix of order $6$ is a $6\times 6$ matrix with unimodular entries and mutually orthogonal rows. The paper discusses previously constructed one-, two-, and thre…

A complex Hadamard matrix of order $6$ is a $6\times 6$ matrix whose entries have modulus one and whose rows are mutually orthogonal. The paper considers the isolated spectral matr…