PR ( i ) = ( 1 - d ) + d ( PR ( t 1 ) C ( t 1 ) + PR ( t 2 ) C ( t 2 ) + ??? + PR ( t n ) C ( t n ) ) , ( 1 ) where PR(i) is the page rank of webpage i, d is a damping factor that can be a constant (e.g., 0.85), tj is a webpage j that links to webpage i, and C(tj) is the number of outbound HTML links from webpage j.