The modern information retrieval systems become the basic building block of the modern-day web search engines. The factors that affect the performance of the information retrieval system also affect the web search engines performance. Information retrieval systems' performance depends on the index terms, and their occurrence frequency. Hence, the small variation in the index term's frequency alters the information retrieval systems' performance. This work tries to analyze the variation in the performance of information retrieval systems which is due to the changes in the index terms frequency. Based on the occurrence frequency, the index terms are classified as 'Low', and 'High' frequency terms; and their performances are also recorded. Low-frequency terms tend to decrease the information retrieval systems' performance. In contrast, the performance of high-frequency terms is better than its counterpart. High-frequency terms do 10% performance improvement in comparison with the low-frequency terms. By deleting the low-frequency index terms, we can save up to 65% of index terms with the maximum of 26% degradation in IR system's performance. This trade-off seems to be well paid. Finally, it is confirmed that the system which uses the whole index terms tender better performance than the system which uses either the low or the high-frequency terms.
外文書商品之書封，為出版社提供之樣本。實際出貨商品，以出版社所提供之現有版本為主。部份書籍，因出版社供應狀況特殊，匯率將依實際狀況做調整。
無庫存之商品，在您完成訂單程序之後，將以空運的方式為你下單調貨。為了縮短等待的時間，建議您將外文書與其他商品分開下單，以獲得最快的取貨速度，平均調貨時間為1~2個月。
為了保護您的權益，「三民網路書店」提供會員七日商品鑑賞期(收到商品為起始日)。
若要辦理退貨，請在商品鑑賞期內寄回，且商品必須是全新狀態與完整包裝(商品、附件、發票、隨貨贈品等)否則恕不接受退貨。
