due to the lack of users knowledge of the collections used by search engines and in general retrieval systems, users can not express their information need appropriately in queries. in other words, they do not have enough experience to formulate their needs to find related documents. the idea of user’s query expansion aims to help users to improve and correct the queries. in fact, retrieval sys...

pupose: this research aims to investigate how users expand their queries when encountered with irrelevant retrievals and through examine the degree of match between users' expanded subject queries and the list of persian subject headings. furthermore, it compares the patterns of query expansion in two subject areas: 1) agriculture (applied sciences); 2) education and psychology (humanities). me...

Content-based image retrieval and text-based image retrieval are two fundamental approaches in the field of image retrieval. The challenges related to each of these approaches, guide the researchers to use combining approaches and semi-automatic retrieval using the user interaction in the retrieval cycle. Hence, in this paper, an image retrieval system is introduced that provided two kind of qu...

Principal aim of a search engine is to provide the sorted results according to user’s requirements. To achieve this aim, it employs ranking methods to rank the web documents based on their significance and relevance to user query. The novelty of this paper is to provide user feedback-based ranking algorithm using reinforcement learning. The proposed algorithm is called RRLUFF, in which the rank...