The 2021 IEEE International Conference on Big Data will now be taking place virtually. Please see http://bigdataieee.org/BigData2021/Workshops.html for a list of all associated workshops, and http://bigdataieee.org/BigData2021/SpecialSymposium.html for a list of all special symposium and http://bigdataieee.org/BigData2021/SpecialSession.html for a list of all special sessions.