3 papers
math.CO2026
Equivalence of Complex Hadamard Matrices
Patric R. J. Östergård, Tuomo Valtonen
Symmetry in the context of equivalence or isomorphism is a fundamental and natural concept in any study of discrete structures. Symmetries are also important for non-discrete struc…
math.CO2026
Classification of Symmetric Hadamard Matrices Up to Order 32
Tuomo Valtonen
In this paper, symmetric Hadamard matrices are classified up to Hadamard equivalence for all orders at most 32. In particular, an error in the previous classification of symmetric…
math.CO2025
Non-affine Families of 8 x 8 Complex Hadamard Matrices
Tuomo Valtonen
Six non-affine 3-parameter families of complex Hadamard matrices of order 8 are presented. These families contain Hadamard matrices that are not equivalent to any previously known…