The version of this paper that was initially published was replaced on September 20, 2016, after the authors corrected several minor issues. Here are the differences between the final version and the initially published version: 

p. 1062 "at the course-level and the concept-level directed graphs" -> "both at he course-level and at the concept-level"
p. 1064 "recent advances in deep learning" -> "recent advances in representation learning"
p. 1066 "matrix X and Y" -> "matrices X and Y"
p. 1066 "with respect the new" -> "with respect to the new"
p. 1066 "... in the test set, we score each course pair ..." -> "... in the test set. We score each course pair ..."
p. 1071 "for visualization purpose" -> "for visualization purposes"
p. 1074 "diagonal element" -> "diagonal elements"
p. 1085 "prerequisite relationship" -> "prerequisite relationships"
p. 1088 "multilingual nlp" -> "multilingual NLP"