網際網路的快速發展使得推薦系統廣泛被運用在網站上。推薦系統可以幫助使用者減少搜尋項目的時間並提供優選項目給使用者。過去有關推薦系統的研究中,協同過濾式推薦已廣泛且成功地被應用於網路推薦上,隨著近年社群網路的發展,現在許多學者亦透過使用者彼此間的信任關係做為協同過濾(Collaborative Filtering)推薦之研究,並稱之為以信任為基礎的推薦系統(Trust-based Recommender System: TBRS),此系統中最重要的一項研究議題即如何定義最佳的信任初始值。 過去研究有關信任初始值的設定通常為隨機或直接設定,然而這些初始值均未考量使用者間的正向或負向關係,為了能找出使用者間的正負向關係,本研究運用社群間的使用者評論作為分析使用者間的關係,運用TF-IDF算法計算每個評論的特徵向量,再將評論之特徵向量輸入支持向量機(Support Vector Machine)進行信任模型的訓練,最後結合信任模型(Trust Model)與信任推演模型(Trust Propagation Model)建立個人的信任網路(Trust Network)。 本研究提出一個以網路社群評論信任值為基礎之協同過濾式推薦系統,本研究改善過去信任初始值之設定方法,經實驗結果顯示,本研究之成果優於其它以信任為基礎之推薦方法。
Due to the repaid growth of Internet, the recommender systems are widely used as the network service. Recommender system can help user reducing the search cost and providing a list of suitable items for the user. In the past study, Collaborative Filtering Recommendation (CF) has been widely applied and successfully used in the Internet. Now, with the popularity of social network, many researchers have proposed using trust between users for collaborative filtering recommendation. This kind of approach we also call it as the Trust-based Recommender System (TBRS). And, one of the important issues about TBRS is how to find and define the optimal trust values. In the past study, the initial trust value is usually set by a random number or directly set by a certain value. The initial trust values shall represent positive or negative relationship between users. However, the positive/negative relationship of initial trust values did not considered in the past studies. In order to find out the positive/negative relationship, this research analyzed the users’ comment of social network. The features of these comments are analyzed and derived by using Term Frequency-Inverse Documents Frequency (TF-IDF) method. To obtain the training model for finding the positive/negative relationship, these features are then classified by using Support Vector Machine (SVM). The obtained Trust Model and the Trust Propagation Model are then integrated to generate the user’s trust network model. This research has proposed a trust based recommender system by analyzing user comments of social network. The proposed method improves the finding of initial trust value. From the experiments results, it proves that the proposed method has better prediction outcome than other methods.