phyllis@utcsrgv.UUCP (Phyllis Eve Bregman) (04/06/84)
****
UofT Department of Computer Science Seminar Schedule for
the week of April 9th, 1984
Thursday, April 12th, 4:00 P.M., GB244: Dr. Paolo Atzeni,
Instituto di Analisi dei Sistemi ed Informatica, Rome, Italy:
"Functional dependencies and constraints on null values in
database relations".
ABSTRACT: The use of null values in relational databases allows
us to deal with incomplete information, increasing the capability
and flexibility of relations in capturing the semantics of the
reality of interest, but it is often important to control their
presence in relations. To this end, two classes of integrity
constraints, namely "existence constraints" and "disjunctive
existence constraints" have recently been proposed.
In the talk we consider the interaction between these constraints
and functional dependencies, when the no-information interpretation
is assumed for the null values. We show that the implication problem
for the joint classes is solvable...[the last line is illegible ...peb]
--
Phyllis Eve Bregman
CSRG, Univ. of Toronto
{decvax,linus,ihnp4,uw-beaver,allegra,utzoo}!utcsrgv!phyllis
CSNET: phyllis@toronto
(416) 978 6985