Omar Benjelloun Anish Das Sarma Alon Y. Halevy Martin Theobald Jennifer Widom Databases with uncertainty and lineage. 243-264 2008 17 VLDB J. 2 http://dx.doi.org/10.1007/s00778-007-0080-z db/journals/vldb/vldb17.html#BenjellounSHTW08