The evaluations of FTF-IDF scoring for fresh information retrieval

Fresh information is important for real business. However, conventional search engines are not suited for fresh information retrieval because they are based on centralized architecture. So, we have developed a distributed search engine, cooperative search engine (CSE), which based on distributed architecture. CSE can search fresh information in a short time. The cost of fresh information retrieval is O(1) in the average case, but O(n) in the worst case. So, CSE is scalable, because it is not depended on the system scale. However, even if the performance is good, it is not enough for fresh information retrieval. The value of information is determined by both freshness and relevance. Traditional ranking methods consider either freshness or relevance. So, we propose FTF-IDF scoring which considers both freshness and relevance. In this paper, we evaluate its effects.