What is 'Postgres'?

Hi,

I recently found a publication on database rule systems by Jennifer Widom, IBM
Almaden Research Center, referenced below. This paper arranges a set of
database management systems along a spectrum, which ranges from deductive
database systems that are more based on logic, to active database systems
that are primarily based on ECA rule processing. At the right end of the
spectrum there is a DBMS called 'Postgres', and I wonder if this one could be
'our' PostgreSQL. I never heared about something called 'Postgres', but maybe
this could be a name for the actual PostgreSQL used in the past. However, I
think that there should be no doubt that PostgreSQL should be placed at the
very right side of the spectrum.

Can anyone provide a clarification?

Here is the reference:

J. Widom. Deductive and Active Databases: Two Paradigms or Ends of a Spectrum?
Proceedings of the First International Workshop on Rules in Database Systems,
pages 306-315, Edinburgh, Scotland, August 1993.

http://www-db.stanford.edu/pub/papers/spectrum.ps

Thank you,
Markus Wagner