Chapter 15, Problem 13PE

Explanation of Solution

Algorithm to find the desired set of documents:

Initially, make the list L empty;

for (each keyword c in set of keywords S) do begin

let D := the list of documents identifiers related to current c;

for (each document identifier d in the list D) do

if (a record R with d as document identifier is on the list L) then

R.reference_count := R.reference_count + 1;

else begin

make a new record R;

R.document_id := d;

R.reference_count := 1;

Add record R to list L;

end;

end;

for(each record R in list L) do

if (R.reference_count >= k) then

display R;

Explanation:

• Here, consider “S” is the set of “n” keywords and “L” is the required list. This list is initially empty.
• First “for each” document identifier calculate its reference count...