The Dehn invariant is a constant defined using the angles and edge lengths of a three-dimensional polyhedron. It is significant because it remains constant under polyhedron dissection and reassembly. Dehn showed that two interdissectable polyhedra must have equal Dehn invariants, settling the third of Hilbert's problems. Later, Sydler showed that two polyhedra can be dissected into each other iff they have the same volume and the same Dehn invariant.

dihedral angle | dissection | Ehrhart polynomial | Hilbert's problems | polyhedron dissection

PolyhedronData

Max Wilhelm Dehn