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From: mwang@watmath.UUCP (mwang)
Newsgroups: ont.events
Subject: UW Data Bases Seminar, Dr. Vardi on "On the Semantics of Updates in Databases"
Message-ID: <5333@watmath.UUCP>
Date: Tue, 31-May-83 09:41:37 EDT
Article-I.D.: watmath.5333
Posted: Tue May 31 09:41:37 1983
Date-Received: Wed, 1-Jun-83 01:27:18 EDT
Expires: Sat, 11-Jun-83 00:00:00 EDT
Organization: U of Waterloo, Ontario
Lines: 32


     _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