4x4 complex matrix multiplication in 48 scalar multiplications, first below Strassen's 49 in characteristic 0 (AlphaTensor had already reached 47 in characteristic 2); Dumas, Pernet and Sedoglavic later hit 48 with rational coefficients, removing the complex arithmetic.
Source review pending. Imported from the original notes; linked claims and artifacts have not been re-audited in this restructuring.