کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4950801 | 1441033 | 2018 | 4 صفحه PDF | دانلود رایگان |
- We study the first deterministic algorithm for constructing round-trip spanners.
- Our deterministic algorithm out-performs the state-of-the-art randomized algorithm.
- We re-raise the question that how best we can hope for the stretch-size trade-off.
In this paper, we study the deterministic construction of round-trip spanners for weighted directed graphs. We propose a deterministic algorithm which constructs, for any n-vertex graph G(V,E), a round-trip spanner H(V,Eâ²âE) of stretch 2k+ϵ and size O((k/ϵ)â n1+1/klogâ¡(nw)), where w is the maximum edge weight of G. Notably, this is the first deterministic construction of round-trip spanners and its stretch-size trade-off even improves the previous state-of-the-art randomized algorithm by Roditty et al. More specifically, the size is asymptotically reduced by a factor of k while the stretch factor remains the same. The result is the first clear improvement on round-trip spanners after about ten years and re-raises the open question that how best we can hope for the stretch-size trade-off of round-trip spanners in digraphs.
Journal: Information Processing Letters - Volume 129, January 2018, Pages 57-60