A Hybrid Recommender System for Gaussian Mixture Model and Enhanced Social Matrix Factorization Technology Based on Multiple Interests

Table 2

Description and default values of parameters.

Symbol	Description	Default value
	The regularization constant of user feature in [18–22].	= 0.1
	The regularization constant of item feature in [18–22].
	The regularization constant of user’s trust in [18, 19]
	The regularization constant of social relationships between items.
	The tradeoff parameter plays the role of adjusting the effects of interpersonal trust between users in [21, 22].
	The tradeoff parameter plays the role of adjusting the effect of social relationships between items.
	The tradeoff parameter plays the role of adjusting the effects from recommendations of neighbors and trusted friends in [18].
	The number of clusters.	k = 15
	The dimension of latent feature space in [18, 19, 21].	f = 10
	The number of nearest neighbors for the active user.	100
	The tradeoff parameter controls the influence of the common item set rated by users.
	The tradeoff parameter controls the influence of time attenuation factor.
	The tradeoff parameter controls the influences from the similarities and trust relationships among users,
	The tradeoff parameter controls the effects of similarity between users and the time-weighted similarity between users.	= 0.5
	The tradeoff parameter controls the effects of the error caused by the estimated values in [23].	= 0.5