Descriptive interpretation

According to Rudolf Carnap, in logic, an interpretation is a descriptive interpretation (also called a factual interpretation) if at least one of the undefined symbols of its formal system becomes, in the interpretation, a "descriptive sign" (i.e., the name of single objects, or observable properties). In his "Introduction to Semantics" (Harvard Uni. Press, 1942) he makes a distinction between formal interpretations which are "logical interpretations" (also called "mathematical interpretation" or "logico-mathematical interpretation") and "descriptive interpretations": a formal interpretation is a "descriptive interpretation" if it is not a "logical interpretation".
Attempts to axiomatize the empirical sciences, Carnap said, use a "descriptive interpretation" to model reality.: the aim of these attempts is to construct a formal system for which reality is the only interpretation. - the world is an interpretation (or model) of these sciences, only insofar as these sciences are true.
Any non-empty set may be chosen as the domain of a descriptive interpretation, and all n-ary relations among the elements of the domain are candidates for assignment to any predicate of degree n.
Examples.
A sentence is either "true" or "false" under an "interpretation" which assigns values to the logical variables. We might for example make the following assignments:
Individual constants
Predicates:
Sentential variables:
Under this interpretation the sentences discussed above would represent the following English statements: