Toman, DavidWeddell, Grant2021-04-232021-04-2320202020http://dx.doi.org/10.1007/s13218-020-00666-7https://dl.gi.de/handle/20.500.12116/36299A sound inference procedure is presented for removing operations that eliminate duplicates in queries formulated in a bag-algebra. The procedure is shown complete for positive queries over finite databases, and operates by appeal to logical consequence problems for feature-based description logics in which a TBox embeds an object-relational schema. For unions of conjunctive queries in which an embedded schema excludes cover constraints, the procedure runs in PTIME, and in EXPTIME otherwise.Text/Journal Article10.1007/s13218-020-00666-71610-1987