A framework for modeling query semantics as graph properties is
presented. In this framework, a single
definition of a query automatically gives rise to several
 semantics for  evaluating that query under  varying
 degrees of incomplete 
information. For example, defining natural joins 
automatically gives rise to full disjunctions. 
Two  of the proposed semantics have incremental-polynomial-time
query-evaluation algorithms  for all types of queries that can 
be defined in this framework. Thus, the proposed framework generalizes
previous definitions of semantics for incomplete information and
improves previous  complexity results for query evaluation. 

%%% Local Variables: 
%%% mode: latex
%%% TeX-master: "main"
%%% End: