“…Prediction and recommendation in social collaborative platforms have been widely studied. These work can be further categorized into two groups: (i) finding experts to perform a certain platform tasks or activities [1,6,10,19,21,31,37,39,41,42] and (ii) recommending content or activities to users in the platforms [7,9,11,32,34,43]. For work in group (i), there were work which proposed methods to find experts to answer questions in Stack Overflow [6,21,31,37,39], while for GitHub, experts are predicted if they will review pull-requests and code for repositories [19,41,42].…”