Abnormal Profiles Detection Based on Time Series and Target Item Analysis for Recommender Systems

Table 2

An example of rating matrix and attack profiles.

	Item1	Item2	Item3	Item4	Item5	⋯	Itemn
User1	5	2	3	0	0	⋯	5
User2	2	0	4	1	2	⋯	3
User3	4	2	3	0	5	⋯	0
User4	0	3	0	3	4	⋯	3
	2	0	4	1	2	⋯	3
Attacker1	2	1	0	0	5	⋯	4
Attacker2	2	2	0	0	5	⋯	3
Attacker3	1	2	0	0	5	⋯	2
	2	0	0	0	5	⋯	4
Count (5)	2	2	2	2	9	⋯	3