کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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430598 | 688056 | 2012 | 13 صفحه PDF | دانلود رایگان |
We give a simple polynomial-time algorithm to exactly count the number of Euler tours (ETs) of any Eulerian generalized series-parallel graph, and show how to adapt this algorithm to exactly sample a random ET of the given generalized series-parallel graph. Note that the class of generalized series-parallel graphs includes all outerplanar graphs. We can perform the counting in time O(mΔ3)O(mΔ3), where Δ is the maximum degree of the graph with m edges. We use O(mnΔ2logΔ) bits to store intermediate values during our computations. To date, these are the first known polynomial-time algorithms to count or sample ETs of any class of graphs; there are no other known polynomial-time algorithms to even approximately count or sample ETs of any other class of graphs. The problem of counting ETs is known to be ♯P-complete for general graphs (Brightwell and Winkler, 2005 [2]) also for planar graphs (Creed, 2010 [3]).
Journal: Journal of Discrete Algorithms - Volume 10, January 2012, Pages 110–122