Grant, JohnGryz, J.Minker, JackIn this paper we study the problem of updating disjunctive databases, which contain indefinite data given as positive injunctive closes. We give correct algorithms for the insertion of a clause into and the deletion of a clause from such databases. Although the algorithms presented here are oriented towards model trees, they apply to any representation of minimal models. (Also cross-referenced as UMIACS-TR-95-11)en-USTechnical Report