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Shortest paths in arbitrary plane domains

Published online by Cambridge University Press:  09 November 2020

L. C. Hoehn
Affiliation:
Department of Computer Science & Mathematics, Nipissing University, 100 College Drive, Box 5002, North Bay, ON P1B 8L7, Canada e-mail: loganh@nipissingu.ca
L. G. Oversteegen*
Affiliation:
Department of Mathematics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
E. D. Tymchatyn
Affiliation:
Department of Mathematics and Statistics, University of Saskatchewan, 106 Wiggins Road, Saskatoon, SK S7N 5E6, Canada e-mail: tymchat@math.usask.ca
*
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Abstract

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Let $\Omega $ be a connected open set in the plane and $\gamma : [0,1] \to \overline {\Omega }$ a path such that $\gamma ((0,1)) \subset \Omega $ . We show that the path $\gamma $ can be “pulled tight” to a unique shortest path which is homotopic to $\gamma $ , via a homotopy h with endpoints fixed whose intermediate paths $h_t$ , for $t \in [0,1)$ , satisfy $h_t((0,1)) \subset \Omega $ . We prove this result even in the case when there is no path of finite Euclidean length homotopic to $\gamma $ under such a homotopy. For this purpose, we offer three other natural, equivalent notions of a “shortest” path. This work generalizes previous results for simply connected domains with simple closed curve boundaries.

Type
Article
Copyright
© Canadian Mathematical Society 2020

Footnotes

L.C.H. was partially supported by NSERC grant RGPIN 435518. L.G.O. was partially supported by NSF-DMS-1807558. E.D.T. was partially supported by NSERC grant OGP-0005616.

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