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Consider the following pages and the set of web pages that they link to: Page A

ID: 3548967 • Letter: C

Question

Consider the following pages and the set of web pages that they link to:

Page A points to page C.

Page B points to page C.

Page C points to page D.


Consider running the PageRank algorithm on this subgraph of pages. Assume d = 0.85. Simulate the algorithm for three iterations, assuming that we start at Page A. Show the page rank scores for each page for each iteration. Order the elements in the vectors in the sequence: A, B, C, D.


use this way in your computations for this question



At t = 0 an initial probability distribution is assumed, usually PR (pi; 0) = 1/N At each time step, the computation, as detailed above, yields PR (p; t + 1) = 1 - d/N + d PR (pj; t)/L(pj),

Explanation / Answer

At t=0 PR(A) = PR(B) = PR(C) = PR(D) = 0.25



At t=1 PR(A;1) = (1-0.85)/4 = 0.0625, PR(B;1) = (1-0.85)/4 = 0.0625,


PR(C;1) = (1-0.85)/4 + 0.85*( PR(A;0)/1 + PR(B;0)/1 ) = 0.0625 + 0.85*0.5 = 0.4875


PR(D;1) = (1-0.85)/4 + 0.85*( PR(C;0)/1) = 0.0625 + 0.85*0.25 = 0.275



PR(A;2) = 0.0625, PR(B;2) = 0.0625


PR(C;2) = 0.0625 + 0.85*(PR(A;1)/1 + PR(B;1)/1) = 0.0625 + 0.85*0.125 = 0.16875


PR(D;2) = 0.0625 + 0.85*(PR(C;1)/1) = 0.0625 + 0.85*(0.4875) = 0.4768



PR(A;3) = 0.0625, PR(B;3) = 0.0625


PR(C;3) = 0.16875


PR(D;3) = 0.0625 + 0.85*(PR(C;2)/1) = 0.0625 + 0.85*(0.4768) = 0.4678