In this paper, we are interested in answering the following research question: “ Is it possible to form effective groups in virtual communities by exploiting trust information without significant overhead, similarly to real user communities? ” In order to answer this question, instead of adopting the largely used approach of exploiting the opinions provided by all the users of the community ( called global reputation ) , we propose to use a particular form of reputation, called local reputation. We also propose an algorithm for group formation able to implement the proposed procedure to form effective groups in virtual communities. Another interesting question is how to measure the effectiveness of groups in virtual communities. To this aim we introduce the Gk index in a measure of the effectiveness of the group formation. We tested our algorithm by realizing some experimental trials on real data from the real world EPINIONS and CIAO communities, showing the significant advantages of our procedure w.r.t. another prominent approach based on traditional global reputation.

中文翻译：

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评估虚拟社区中的组建

在本文中，我们有兴趣回答以下研究问题：“是否有可能通过利用信任信息在虚拟社区中形成有效的组而无需花费大量资源，类似于真实用户社区？为了回答这个问题，我们建议采用一种特定形式的声誉，称为本地声誉，而不是采用广泛使用的方法来利用社区所有用户提供的意见（称为全球声誉）。我们还提出了一种用于组形成的算法，该算法能够实施所提出的程序以在虚拟社区中形成有效的组。另一个有趣的问题是如何衡量虚拟社区中群体的有效性。为此，我们引入Gk指数来衡量组群形成的有效性。