Hyperlog is a declarative, graph-based language that supports database
querying and update.  It visualises schema information, data, and query output
as sets of nested graphs, which can be stored, browsed and queried in a
uniform way. Thus, the user need only be familiar with a very small set of
syntactic constructs.  Hyperlog queries consist of a set of graphs that are
matched against the database.  Database updates are supported by means of
programs consisting of a set of rules.  This paper discusses the formulation,
evaluation, expressiveness and optimisation of Hyperlog queries and programs.
We also describe a prototype implementation of the language, and we compare
and contrast our approach with work in a number of related areas, including
visual database languages, graph-based data models, database update languages
and production rule systems. <P>

Index terms: database browsing, database query languages,
database update languages, graph-based models and languages,
hypernodes, visual database languages.