隨著網際網路的普及與電子郵件的廣泛使用，垃圾郵件的數量日益增多，造成電子郵件使用者的不便。若能將郵件伺服器與資料探勘、人工智慧技術相結合，建立一套自動學習及自動過濾垃圾郵件的機制，將可幫助電子郵件者享有一個乾淨清新的收信環境。
　　本研究提出一套區域聯防架構來防堵垃圾郵件的散播，在該架構下，需要一套基於規則的資料探勘與人工智慧演算法，約略集合理論符合該架構之需求。約略集合理論由波蘭邏輯學家Palwak所提出，是個基於規則的資料探勘與人工智慧演算法，適合用來尋找不精確、不完整資料的隱含知識。
　　本研究實際建立一個以約略集合理論為基礎的垃圾郵件過濾器，找出垃圾郵件的特徵規則，並使用這些垃圾郵件特徵規則來過濾垃圾郵件。本研究發展之系統可附加於傳統的電子郵件協定上，適用於大部分現存的郵件伺服器。該系統支援中、日、韓等雙位元組文字語系，克服大部分垃圾郵件過濾軟體僅能處理英文語系郵件的問題。而在未來的後續研究中，可發展一套郵件伺服器間垃圾郵件規則的交換機制，實現區域聯防架構。

With the popularization of Internet and the wide use of electronic mails, the number of spam mails grows continuously. The matter has made e-mail users feel inconvenient. If e-mail servers can be integrated with data mining and artificial intelligence techniques and learn spam rules and filter out spam mails automatically, they will help every person who is bothered by spam mails to enjoy a clear e-mail environment.
In this research, we propose an architecture called union defense to oppose against the spread of spam mails. Under the architecture, we need a rule-based data mining and artificial intelligence algorithm. Rough sets theory will be a good choice. Rough sets theory was proposed by Palwak, a logician living in Poland. It is a rule-based data mining and artificial intelligence algorithm and suitable to find the potential knowledge of inexact and incomplete data out.
This research developed a spam filter based on rough sets theory. It can search for the characteristic rules of spam mails and can use these rules to filter out spam mails. This system set up by this research can be appended to most of existing e-mail servers. Besides, the system support Chinese, Japanese and Korean character sets and overcome the problem that most spam filters only can deal with English mails. We can develop a rule exchange approach between e-mail servers in the future works to realize union defense.

第一章 序論 8
第一節 研究背景 8
第二節 垃圾郵件 9
第三節 研究動機 11
第四節 研究步驟 14
第二章 相關研究 17
第一節 垃圾郵件相關研究 17
第二節 資料探勘與人工智慧 24
第三節 約略集合理論 26
第三章 系統設計 30
第一節 郵件內容擷取模組 31
第二節 郵件管理模組 32
第三節 規則運算模組 33
第四節 規則管理模組 35
第五節 郵件過濾模組 36
第四章 系統建置與驗證 39
第一節 資料庫建置 40
第二節 郵件內容擷取模組建置 42
第三節 郵件管理模組建置 45
第四節 規則運算模組建置 46
第五節 規則管理模組建置 47
第六節 郵件過濾模組建置 49
第七節 系統驗證 52
第五章 結論 56
第一節 結論 56
第二節 未來發展 57
參考文獻 58
附錄 60

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[12] EBRSC Rough Set software links. http://www2.cs.uregina.ca/~roughset/software.html
[13] GROBIAN. http://www.infj.ulst.ac.uk/~cccz23/grobian/grobian.html
[14] Rough Analysis. http://www.lsi.upc.es/~ealvarez/rough.html
[15] DATALOGIC. http://ourworld.compuserve.com/homepages/reduct/
[16] Rosetta. http://www.idt.unit.no/~aleks/rosetta/rosetta.html
[17] Rough Enough. http://www.trolldata.no/renough/
[18] ROSE. http://www.cs.put.poznan.pl/research/labDec/roughset/
[19] RSES. http://logic.mimuw.edu.pl/~rses/start.html
[20] K-DYS. http://www.rs-systems.com/
[21] Aleksander