The truth conditional representation is domain independent. The
expressions (predicate and argument names) that appear in the
representation have no particluar significance in the current database
by themselves. To produce a suitable query, the notions used must be
mapped to relevant fragments of a relational calculus query that is
appropriate for the current database. This is done using information
in the *Extended Data Model* (EDM). The most
convenient relational calculus to produce at this stage is the
*Universal Relational Calculus*. (This is also called the
*Untyped Relational Calculus* in some reports on
*Squirrel*.)

The expression:

is a representation of:{fva1;exists(a,[*,a]:boss&[fva1,a]:boss)}

As can be seen, there is some redundancy in this query, as a result of the simple EDM inspired translation. This redundancy is removed later by some general optimisation strategies.

Chris Fox, September 1995