Puncture (topology)
(Redirected from Once-punctured)
In topology, puncturing a manifold is removing a finite set of points from that manifold.[1] The set of points can be small as a single point. In this case, the manifold is known as once-punctured. With the removal of a second point, it becomes twice-punctured, and so on.
Examples of punctured manifolds include the open disk (which is a sphere with a single puncture), the cylinder (which is a sphere with two punctures), and the Möbius strip (which is a projective plane with a single puncture).[citation needed]
References
- ^ Seifert, H. (1980). Seifert and Threlfall, A textbook of topology. W. Threlfall, Joan S. Birman, Julian Eisner. New York: Academic Press. p. 29. ISBN 978-0-12-634850-7. OCLC 316570650.
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