Hierarchy classification:

1. top of the aat hierarchies
2. Associated Concepts Facet
3. Associated Concepts (hierarchy name)
4. scientific concepts
5. mathematical concepts
6. geometric concepts
7. geometric figures
8. plane figures
9. polygons

Anotations

Scope note:

In geometry, a digons are polygons with two sides or edges and two vertices; pairs of vertices connected by two edges. A digon is degenerate in a Euclidean space, but may be non-degenerate in a spherical space.