A relational database has a number of tables (data matrices). Tables
contains data of various types (numerical, character, date, time,
text), just like a Gifi data structure. But tables are related
to each other. Say we make a data base to manage a journal. We
have a table of associate editors, a table of reviewers, a table
of authors, a table of manuscripts, and a table of issues (for
instance). Associate editors handle manuscripts, and select
reviewers, reviewers review manuscripts, manuscripts get into
issues. This is more complicated then "multilevel" data in which
there is a simple hierarchy (students are in schools).
Can we make a picture of such a database, in the same way in which
HOMALS makes a picture of a single table.
