<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31402761</termId><termName>monogons</termName><termType>PT</termType><termNote><![CDATA[ Polygons having one edge and one vertex, considered an impossible object in Euclidean geometry. In spherical geometry, a finite henagon may be drawn by placing a single vertex anywhere on a great circle; two henagons may be used to construct a dihedron on a sphere. ]]></termNote><termCreatedDate>2026-03-30 20:48:18</termCreatedDate><relation><relationType>UF</relationType><termId>31402762</termId><termName>henagons</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31402763</termId><termName>monogon</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31361605</termId><termName>polygons</termName><termType>PT</termType></relation></term>  </Zthes>