抄録
The importance of web pages as information sources has grown larger as the number of pages has been increasing rapidly. Web pages, however, are not considered as a reliable information sources since they have short life and about half of them are deleted or updated in a year. But, a part of the pages considered as deleted or updated are often moved to other servers or only change their URLs. We have found that about 30 or 40% of the pages considered missing still exist and are even traceable and can be reached by analyzing the pages considered missing. We have found out 23.6% of the pages considered deleted by making the program which can trace the pages by using URL structures and keywords in title, center and selection tags.
