Abstract
We give a short proof of the following theorem of H. I. Levine [2]: Let A? and B be nonintersecting simple closed curves on an orientable surface S (compact or not). (i) If A? is homotopic to zero, then A bounds a closed disk in S. (ii) If A and B are freely homotopic but not homotopic to zero then A ∪ B? bounds a closed cylinder in S.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 337-339 |
| Number of pages | 3 |
| Journal | Pacific Journal of Mathematics |
| Volume | 16 |
| Issue number | 2 |
| DOIs | |
| State | Published - Jan 1966 |
| Externally published | Yes |