Symmetric and skew-symmetric $\{0,\pm 1\}$-matrices with large   determinants
  We show that the existence of $\{\pm 1\}$-matrices having largest possible determinant is equivalent to the existence of certain tournament matrices. In particular, we prove a recent conjecture of Armario. We also show that large submatrices of conference matrices are determined by their spectrum. 
Gary Greaves and Sho Suda
math.CO