隨著電腦以及網際網路的普及，越來越多各領域的資料被數位化，利用電腦幫助儲存及管理資料。有許多資料在數位化的過程中，採用tree的資料結構來表達以及儲存。也因此，如何查詢這些龐大的資料，就成為重要的課題。在本論文中，我們針對具有rooted、labeled以及ordered或unordered等特性的tree結構資料的索引問題，提出稱之為PCS-trie之全新的主記憶體資料庫(Main Memory Database)索引結構，並提出相關的增刪資料及搜尋演算法，以達成加速處理sub-tree query之目標。此索引方法的基礎，在於將tree database中的tree編碼為可完整代表其結構的PREOD code字串，之後再以我們所提出的PCS-trie加以索引。PCS-trie索引結構支援資料庫的動態增刪，且我們也提供了有效率的新增及刪除資料的演算法。本論文中也提出了多種搜尋演算法，使能夠在PCS-trie中進行exact matching、處理query tree含有don’t care部分之查詢、以及fault tolerant等不同類型的查詢。最後，我們以實驗的方法，配合人工產生的實驗資料，來對PCS-trie索引方法的時間及空間等各方面的效率加以檢驗。 / With the popularization of computer and the Internet, more and more data in various domains are digitized in order to take advantage of the power of computing and storing, and use the Internet to spread these informationz. Many data use tree structure to store them in the process of digitization. For this reason, it is a challenge to deal with these enormous data. In this paper, we present an approach to the search problem for these rooted labeled trees. We show a novel index structure, PREOD code Search trie (PCS-trie), and related algorithms for construction and search of PCS-trie, to speed up the sub-tree query to a tree database. The fundamental of this reaseach is to encode trees in tree database by PREOD code, in which the structure information of a tree can be reserved completely. Then we index these PREOD codes by PCS-trie. PCS-trie supports dynamic insertion and deleteion of PREOD codes. PCS-trie can handle three different types of query requirements: exact sub-tree query, query with don’t cares, and fault-tolerant query. Finally, we have conducted a series of experiments to evaluate the performance of PCS-trie and related algorithms. Experimental results obtained by running our techniques on synthetic data demonstrate the good performance of the proposed approach.

在網際網路應用普及的推波助瀾下，全球經濟一體化已然成為時代之趨勢，造就了網際網路商業交易之盛行。基於電子商務交易之特性與傳統課稅觀念有著重大之差異性，除了對企業營運效率提升與交易成本之降低有助益外，企業更可利用網路無國界等特性，發展出新的逃漏稅方法，此將造成租稅稅基之流失。而我國電子商務交易量隨著時代的巨輪正加速成長中，電子商務之課稅問題，亦正逐一地浮現。 　　營業稅是我國的第二大稅，掌握營業稅當可掌握大部分所得稅之基源。本研究係從稅務稽核人員的角度切入，完整探討電子商務的運作內涵，進而瞭解電子商務因其特性所衍生課稅問題徵結之所在。依課稅管轄權、課稅觀念及稽徵技術等三個構面建立研究架構，嘗試在我國現行營業稅法規定下，檢討電子商務跨國線上傳送數位化商品及服務之適用性、衍生之稅收徵管（包含稅收損失之分析）問題，併歸納先進國家及國際組織之各種擬議文獻與實施經驗作為借鏡，據此結合國際共識與稽核實務提出具體建議，供政府因應電子商務發展而即將制定之租稅政策及修改營業稅制之參考，未來在不增加稅務行政成本及納稅人依從成本下，取得完整的交易稽核軌跡，防杜租稅逃漏，期能兼顧網路經濟發展及財政稅收之確保。 / After the rapid development of Internet and that with inciting e-commerce to be widely adopted by the most of business transaction, the Internet offers business opportunities to provide their products and services in a web-server without having a physical presence, which will erode tax revenue bases of a jurisdiction. The volume of E-commerce trade is accelerating in Taiwan. Many noticeable questions of taxing E-commerce will be seen in the near future. 　　Business tax is the second revenue of major taxes, collecting it could be holding the sources of income tax. From a view of a tax auditor, this research will explore the operation of E-commerce completely, and understand where the problem is generated by E-commerce. The framework of this study is composed of the taxing jurisdiction, taxing concept and collecting technique. Trying to test E-commerce transmitting digital goods and service on-line, and to test the adequacy of the existing laws and regulations on business tax are the major themes of this work. The suggestions of tax policy will be made according to the reference from the existing literature and the practice from advanced countries and international organizations. Considering the administration and compliance cost in the near future, how can we refrain from tax evasion and expect to increase tax revenue are all important to the development of economic activity through Internet.