Not yet checked. Suggested by an AI model, 2026-10-08.

• Archimedean solids

  Plate XIII of Pacioli’s Divina proportione, 1509, drawn by Leonardo and labelled “Hexaedron sive Cubus Abscisus Elevatus solidum”: a cut-down cube with a pyramid raised on every face. The open-frame version of the same solid shows through from the facing page.

  An AI reviewer had doubts, 2026-10-09: The source page says the book "It also contains a discourse on the regular and semiregular polyhedra", which loosely fits the claim, but it never names Archimedean solids. The plate shown is a cube with a pyramid raised on every face, with triangular faces that are not regular, so it does not show an Archimedean solid, which the library entry defines by regular faces.

  Source
• Truncation

  The solid on plate XIII is a cube with its corners cut away, the first step of the walk from cube to octahedron, here with a pyramid raised on each face.

  An AI reviewer had doubts, 2026-10-09: The library's entry describes truncation as "Slice every corner off a cube and keep slicing." The plate shows a cube with pyramids raised on its faces, but I cannot see cut corners in the woodcut, and nothing in the evidence translates the caption word "Abscisum", so the corner-cutting part of the note is not borne out.

  Source