“…Although many machine learning topics and techniques are related to LL, e.g., lifelong learning (Thrun, 1998, Chen and Liu, 2014b, Silver et al, 2013, transfer learning (Jiang, 2008, Pan andYang, 2010), multi-task learning (Caruana, 1997), never-ending learning (Carlson et al, 2010), selftaught learning (Raina et al, 2007), and online learning (Bottou, 1998), there is still no unified definition for LL.…”