Adaptive topical web crawling for domain-specific resource discovery guided by link-context

Topical web crawling technology is important for domain-specific resource discovery. Topical crawlers yield good recall as well as good precision by restricting themselves to a specific domain from web pages. There is an intuition that the text surrounding a link or the link-context on the HMTL page is a good summary of the target page. Motivated by that, This paper investigates some alternative methods and advocates that the link-context derived from reference page's HTML tag tree can provide a wealth of illumination for steering crawler to stay on domain-specific topic. In order that crawler can acquire enough illumination from link-context, we initially look for some referring pages by traversing backward from seed URLs, and then build initial term-based feature set by parsing the link-contexts extracted from those reference web pages. Used to measure the similarity between the crawled pages' link-context, the feature set can be adaptively trained by some link-contexts to relevant pages during crawling. This paper also presents some important metrics and an evaluation function for ranking URLs about pages relevance. A comprehensive experiment has been conducted, the result shows obviously that this approach outperforms Best-First and Breath-First algorithm both in harvest rate and efficiency.