@inproceedings{Ullmanb,
    Address = {New York, NY, USA},
    Author = {Ullman, J. D.},
    BookTitle = {Proceedings of the eighth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems},
    File = {Bottom-up beats top-down for datalog - Ullman (0) (0) - a - a - q.pdf},
    ISBN = {0-89791-308-6},
    Keywords = {database theory and datalog},
    Location = {Philadelphia, Pennsylvania, USA},
    Pages = {140--149},
    Publisher = {ACM},
    Series = {PODS '89},
    Title = {Bottom-up beats top-down for datalog},
    URL = {http://doi.acm.org/10.1145/73721.73736},
    Year = {1989},
    acmid = {73736},
    bdsk-url-1 = {http://doi.acm.org/10.1145/73721.73736},
    bdsk-url-2 = {http://dx.doi.org/10.1145/73721.73736},
    date-added = {2013-04-09 18:53:19 +0000},
    date-modified = {2013-04-18 16:07:06 +0000},
    numpages = {10},
    doi = {10.1145/73721.73736}
}

@inproceedings{Ullmanb, Address = {New York, NY, USA}, Author = {Ullman, J. D.}, BookTitle = {Proceedings of the eighth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems}, File = {Bottom-up beats top-down for datalog - Ullman (0) (0) - a - a - q.pdf}, ISBN = {0-89791-308-6}, Keywords = {database theory and datalog}, Location = {Philadelphia, Pennsylvania, USA}, Pages = {140--149}, Publisher = {ACM}, Series = {PODS '89}, Title = {Bottom-up beats top-down for datalog}, URL = {http://doi.acm.org/10.1145/73721.73736}, Year = {1989}, acmid = {73736}, bdsk-url-1 = {http://doi.acm.org/10.1145/73721.73736}, bdsk-url-2 = {http://dx.doi.org/10.1145/73721.73736}, date-added = {2013-04-09 18:53:19 +0000}, date-modified = {2013-04-18 16:07:06 +0000}, numpages = {10}, doi = {10.1145/73721.73736} }