Q2) We define 3 new operations, (,-), on ordered sets. They are explained with examples.
Let X = {x1, x2, x3, x4, x}, X = {x2, x, x}, and X = {x, xx}. Then
X ∩ Xp = {x, x5}
X ∩ XB = {x1, x, x3, x}
X - XA = {x1, x4}
That is, ∩, ∪, and - are specialized set operations where the order of elements is preserved.
(2.a) Describe how these can be used to implement a retrieval system based on the Boolean Retrieval Model that uses an inverted file structure. That is, we want to process queries such as AB, AvB, -A, etc.
(2.b) Use the table below and construct the inverted lists, Du, for 1 ≤ i ≤ 4.
ti | 1
t2 | 1 1
t3 | 0
t4 | 0
Feedback:
doc.1 | R
doc.5 doc.7 doc.3 doc.6 | 1
1
0
R
0
1
0
1
N N
1
1
1
1
0
1
1
N
(2.c) Determine RSVq of documents {d1, d3, d5} with respect to the following queries. You must use the inverted lists and operations defined in parts (2.a) and (2.b).
-vv- = 1
b(!) iiq = -t^t4V-tAt)
