Tag · 2 problems · 2 fields

Open problems tagged construction

2 problems in the Math Lab index touch construction, spanning Number Theory, Algebra. Each carries a precise statement, an honest status, and a computational line of attack.

Hadamard conjectureNumber Theoryuntouched

A Hadamard matrix — a ±1 matrix with pairwise orthogonal rows — exists for every order divisible by 4.

Williamson matricesAlgebrauntouched

For which odd n do Williamson matrices (four symmetric circulant ±1 matrices with A² + B² + C² + D² = 4nI) exist? Each solution yields a Hadamard matrix of order 4n.