Some Improvements of Existing Approximation Algorithms for the Steiner Problem in Graphs

• Main Authors: Dro, Je-Sen, 卓介生
• Other Authors: Ru-Sheng Liu
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/48915413107789078808

碩士 === 元智工學院 === 電機與資訊工程研究所 === 84 === Steiner tree 的概念可廣泛應用在網路、通訊、以及 VLSI 的設 計等方面。由於其重要性，從80年代開始遂有相當多的論文 探討該項 問題。本論文的研究目的主要在將數個著名的近似演算法 作一整理介 紹，並重新加以證明，改善了部分的近似率（Approxi- mation Ratio） ，同時提出對各近似解作一後置處理，在不增加整 體時間複雜度的情況 下得到更好的結果。 The concept of Steiner tree is widely applied to the design of networks, communications, and VLSI, etc. Due to its importance, there are a lot of papers studying the Steiner tree problem since 1980. The purpose of this thesis is to introduce several famous approximation algorithms, illustrate how they work, and reprove some of them to improve approximation ratios. Finally, a post process for all approximate solutions is proposed such that a better solution may be obtained under the condition of not increasing the time-complexity.