S²NMF: Information Self-Enhancement Self-Supervised Nonnegative Matrix Factorization for Recommendation

Table 1

Symbol description.

Symbol	Definition
	Number of users
	Number of projects
	Set of users,
	Set of projects,
	User-item interaction matrix, the elements are generally nonnegative scores
	The predicted user-item interaction matrix
	The basis matrix
	The data in the reduced feature space, also called the combined coefficient matrix of the basis
	The community indication matrix
	The number of repetitions of matrix decomposition