许多“边界”理论,比如开流形的配领(collaring of an open manifold)、马丁边界(Martinboundary),施罗夫边界(Shilov boundary)以及菲斯滕贝格边界(Fürstenberg boundary)。 拓扑群的波尔紧化由考虑殆周期函数得出。 通过构造一个有反演环几何(inversive
Ramezani, Jahandar; Martin, Mark W.; Matter, Albert. Extinction of Cloudina and Namacalathus at the Precambrian-Cambrian Boundary in Oman. Geology. 2003
Point of the National Boundaries[永久失效連結] International Boundary Study No. 34 – China – Laos Boundary (PDF). US Department of State. 24 June 1964 [17 September