For example,
the PageRank algorithm says that the rank of a page is a function of the sum of the ranks of the pages that link to the page.
If we let PR(p) be the PageRank of page p,
Out(p) be the number of outgoing links from page p,
Links(p) be the set of pages that link to page p and N be the total number of pages in
the index,
then we can define PageRank by