Parameters of Non-Trivial Divisible Design Graphs

The columns are:

• existence
• v - number of vertices
• k - valency
• λ₁ - number of common neighbours of two vertices from the same class
• λ₂ - number of common neighbours of two vertices from different classes
• m - number of classes in the canonical partition
• n - size of classes in the canonical partition
• θ₁^f₁ - positive eigenvalue whose square is k-λ₁, with multiplicity
• θ₂^f₂ - negative eigenvalue whose square is k-λ₁, with multiplicity
• τ₁^g₁ - non-negative eigenvalue whose square is k²-λ₂v, with multiplicity
• τ₂^g₂ - non-positive eigenvalue whose square is k²-λ₂v, with multiplicity
• comments