mwang@watmath.UUCP (mwang) (05/31/83)
_D_E_P_A_R_T_M_E_N_T _O_F _C_O_M_P_U_T_E_R _S_C_I_E_N_C_E _U_N_I_V_E_R_S_I_T_Y _O_F _W_A_T_E_R_L_O_O _S_E_M_I_N_A_R _A_C_T_I_V_I_T_I_E_S _D_A_T_A _B_A_S_E_S _S_E_M_I_N_A_R - Friday, June 10, 1983. Dr. M.Y. Vardi of Stanford University will speak on ``On The Semantics of Updates in Databases.'' TIME: 1.30 PM (Please Note) ROOM: MC 5158 ABSTRACT We suggest here a methodology for updating databases with integrity constraints and rules for deriving inex- plicit information. First we consider the problem of updating arbitrary theories by inserting into them or deleting from them arbitrary sentences. The solution involves two key ideas: when replacing an old theory by a new one we wish to minimize the change in the theory, and when there are several theories that involve minimal changes, we look for a new theory that reflects that ambiguity. The methodology is also adapted to up- dating databases, where different facts can carry dif- ferent priorities, and to updating user views. May 31, 1983