A note on 15/8 & 3/2-approximation algorithms for the MRCT problem∗
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چکیده
Example 1: The tree in Figure 1(a) has 26 vertices in which v1 is a centroid. The vertex v1 is a minimal 1/2-separator. As shown in (b), each branch contains no more than 13 vertices. But v1, or even the edge (v1, v2), is not a 1/3-separator because there exists a subtree whose number of vertices is nine, which is greater than 26/3. The path between v2 and v3 is a minimal 1/3-separator (Frame (c)), and the subgraph that consists of v1, v2, v3, v4, and v5 is a minimal 1/4-separator (Frame (d)).
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تاریخ انتشار 2005