Consider an n-cell containing the origin and suppose its boundary Sn-1 has the following property: every point on Sn-l contains a neighborhood in Sn-l such that any ray from the origin intersecting this neighborhood intersects it exactly once. Then it is shown by using the concept of a covering space that any ray from the origin intersects Sn-1 exactly once.
Proceedings of the Iowa Academy of Science
©1963 Iowa Academy of Science, Inc.
"An Application of Covering Spaces,"
Proceedings of the Iowa Academy of Science, 70(1), 351-353.
Available at: https://scholarworks.uni.edu/pias/vol70/iss1/59