Keywords-Driven and Popularity-Aware Paper Recommendation Based on Undirected Paper Citation Graph

Table 1

Symbol definitions.

Symbol	Definition
	A paper
k1, …, km	A node contains keywords
	An edge of a pair of nodes
Q	Users’ query keywords
K	A set of query keywords
	A set of nodes (papers)
	A set of edges
	Undirected paper citation graph
S(K)	An inverted index
T(Q)	Minimum group Steiner trees
T1(Q)	Optimal solutions
Q^1	A queue in ascending order of number of tree nodes
	Minimum group Steiner trees rooted at
	Paper recommendation results