# monogon

## English

mono- +‎ -gon.

### Pronunciation

• Hyphenation: mon‧o‧gon

### Noun

monogon (plural monogons)

1. (geometry) A one-dimensional object comprising one vertex and one (not necessarily straight) edge both of whose ends are that vertex.
• 1955, Herbert Busemann, The Geometry of Geodesics, page 295:
A geodesic with multiple points contains at least one simple monogon.
• 1981, Harold Abelson and Andrea A. DiSessa, Turtle Geometry: The Computer As a Medium for Exploring Mathematics, →ISBN, page 262:
There are no one-sided closed polygons on a plane. On the cube, however, monogons are a diverse and interesting class of figures.
• 2003, Gordon Baker, translator and editor, Ludwig Wittgenstein and Friedrich Waismann, The Voices of Wittgenstein: The Vienna Circle, Routledge, →ISBN, page 409,
We explain to somebody what is a regular quadrilateral constructed within the circle; then a regular triangle and a regular bi-angle. Now we ask him to draw a regular monogon by analogy, and we probably think that he cannot do this. But what if he draws a point on the circle and says that it is a regular monogon?
2. (geometry) A two-dimensional object comprising one vertex, one edge both of whose ends are that vertex, and one face filling in the hollow formed by that edge.
• 1987, Jonathan L. Gross and Thomas W. Tucker Topological Graph Theory, 2001 Dover Publications edition, →ISBN, page 231,
According to Theorem 4.1.1, such a derived imbedding could be obtained from an imbedded voltage graph with one vertex, $6s+2$ edges, and $4s+2$ faces. Of these faces, $4s+1$ should be 3-sided and satisfy KVL. The other face should be a monogon whose net voltage has order two.
• 2002, Tao Li, "Laminar Branched Surfaces in 3–manifolds", Geometry & Topology 6, page 158,
There is no monogon in $M-int(N(B))$ , ie, no disk $D\subset M-int(N(B))$ with $\partial D=D\cap N(B)=\alpha \cup \beta$ , where $\alpha \subset \partial _{v}N(B)$ is in an interval fiber of $\partial _{v}N(B)$ and $\beta \subset \partial _{h}N(B)$ .
• a. 2006, Thilo Kuessner, "A survey on simplicial volume and invariants of foliations and laminations", in, Paweł Walczak, et al., editors, Foliations 2005, →ISBN, page 295,
An end-compressing monogon for F is a monogon properly embedded in the complimentary[sic] region C which is not homotopic (rel. boundary) into $\partial C$ .
3. (optics) A single-faceted reflector.
• 1991, Beam Deflection and Scanning Technologies, Gerald F. Marshall, editor, Leo Beiser, →ISBN, page 33:
A new optical scanner is described which serves as a monogon or single-facet device, providing one scan per shaft rotation.
• 1999, William L. Wolfe, Infrared Design Examples, Tutorial Texts in Optical Engineering Volume TT36, SPIE Press, →ISBN, page 133,
These devices also start with the monogon, a plane mirror, and include the bigon, a two-sided mirror, the trigon, quadrigon, and general n-gons.

#### Quotations

To be listed under the applicable sense
• 2008, Baris Coskunuzer, Proceedings of the American Mathematical Society, Volume 136, Number 4, pages 1427-1432,
As nonproper embeddedness must produce monogons, one can get a contradiction by using Hass and Scott's surgery arguments for least area objects in [HS].