Starting from the published P72 n=12 point set, I applied an exact integer local search on the 1e-9 grid. For each tetrahedral subset I linearized the signed 4x4 homogeneous determinant, solved the resulting bounded integer improvement problem for increasing move radii, and then recomputed every determinant with exact integer arithmetic. The submitted coordinates are the resulting grid points; no floating-point score is used.
P72 · Heilbronn minimum tetrahedron volume · Discussion