Abstract
The family of \(\varTheta _k\)-graphs is an important class of sparse geometric spanners with a small spanning ratio. Although they are a well-studied class of geometric graphs, no bound is known on the spanning and routing ratios of the directed \(\varTheta _6\)-graph. We show that the directed \(\varTheta _6\)-graph of a point set P, denoted \(\overrightarrow{\varTheta }_6(P)\), is a 7-spanner and there exist point sets where the spanning ratio is at least \(4-\varepsilon \), for any \(\varepsilon >0\). It is known that the standard greedy \(\varTheta \)-routing algorithm may have an unbounded routing ratio on \(\overrightarrow{\varTheta }_6(P)\). We design a simple, online, local, memoryless routing algorithm on \(\overrightarrow{\varTheta }_6(P)\) whose routing ratio is at most 14 and show that no algorithm can have a routing ratio better than \(6-\varepsilon \).
Research supported in part by NSERC.
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Akitaya, H.A., Biniaz, A., Bose, P. (2021). On the Spanning and Routing Ratios of the Directed \(\varTheta _6\)-Graph. In: Lubiw, A., Salavatipour, M., He, M. (eds) Algorithms and Data Structures. WADS 2021. Lecture Notes in Computer Science(), vol 12808. Springer, Cham. https://doi.org/10.1007/978-3-030-83508-8_1
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