For discovering the new URI of a missing web page, lexical signatures, which consist of a small number of words chosen to represent the "aboutness" of a page, have been previously proposed. However, prior methods relied on computing the lexical signature before the page was lost, or using cached or archived versions of the page to calculate a lexical signature. We demonstrate a system of constructing a lexical signature for a page from its link neighborhood, that is the "backlinks", or pages that link to the missing page. After testing various methods, we show that one can construct a lexical signature for a missing web page using only ten backlink pages. Further, we show that only the first level of backlinks are useful in this effort. The text that the backlinks use to point to the missing page is used as input for the creation of a four-word lexical signature. That lexical signature is shown to successfully find the target URI in over half of the test cases.
A lexical signature (LS) is a small set of terms derived from a document that capture the "aboutness" of that document. A LS generated from a web page can be used to discover that page at a different URL as well as to find relevant pages in the Internet. From a set of randomly selected URLs we took all their copies from the Internet Archive between 1996 and 2007 and generated their LSs. We conducted an overlap analysis of terms in all LSs and found only small overlaps in the early years (1996 i¾? 2000) but increasing numbers in the more recent past (from 2003 on). We measured the performance of all LSs in dependence of the number of terms they consist of. We found that LSs created more recently perform better than early LSs created between 1996 and 2000. All LSs created from year 2000 on show a similar pattern in their performance curve. Our results show that 5-, 6- and 7-term LSs perform best with returning the URLs of interest in the top ten of the result set. In about 50 of all cases these URLs are returned as the number one result and in 30 of all times we considered the URLs as not discoved.