Search engine algorithm research (III)-search engine technology

2.2.3 HITS variants

Most of the problems encountered by the HITS algorithm are Because HITS is a purely link-based analysis algorithm without considering the text content. after kleberger proposed the HITS algorithm, many researchers improved HITS and proposed many variant HITS algorithms, mainly including:

2.2.3.1 improvement on HITS by Monika R. Henzinger and Krishna Bharat

Monika R. Henzinger and Krishna Bharat^[7]. Assuming that host A has k Web pages pointing to A document d on host B, the contribution of k documents on host A to Authority B is 1 in total, each document contributes 1/k instead of 1/k in each HITS. Similarly, for the Hub value, assuming that A document t on host A points to m documents on host B, m documents on host B contribute 1 to t's Hub value in total, each document contributes 1/m. The O operation is changed to the following:

I operation:

O operation:

The adjusted algorithm effectively solves problem 2, which is called imp algorithm.

On this basis, Monika R. Henzinger and Krishna Bharat also introduced the content analysis technology of traditional information retrieval to solve 4 and 5. In fact, they also solved problem 3 at the same time. The specific method is as follows: extract the first 1000 words of each document in the root set S and concatenate them as the query topic Q. The similarity between the Dj and topic Q is calculated according to the following formula:

,,= Number of occurrences of item I in the query Q,

= The number of times that item I appears in the document Dj. IDFi is an estimate of the number of documents containing item I on WWW.