Consider a postings intersection between this postings list, with skip pointers:

$359152439606875818489929697100115$

and the following intermediate result postings list $($which hence has no skip pointers$)$:

$3589959799100101$

Trace through the postings intersection algorithm. How often is a skip pointer followed $($ie$.,$ p$1$ is advanced to skip $($p$1))?$

b$.$ How many postings comparisons will be made by this algorithm while intersect$-$ ing the two lists?

c$.$ How many postings comparisons would be made if the postings lists are inter$-$ sected without the use of skip pointers?