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