Nef polygon

The objects are named after the Swiss mathematician Walter Nef (1919–2013),[1] who introduced them in his 1978 book on polyhedra.

[4] In addition, the class of Nef polyhedra is closed with respect to the topological operations of taking closure, interior, exterior, and boundary.

Boolean operations, such as difference or intersection, may produce non-regular sets.

However the class of Nef polyhedra is also closed with respect to the operation of regularization.

[7] The Computational Geometry Algorithms Library, or CGAL, represents Nef Polyhedra by using two main data structures.