# Stratification (mathematics)

Stratification referred to in the mathematical logic an order of predicate symbols, which guarantees that a unique interpretation of a formal logic program exists. In particular, a set of clauses of the mold is referred to just as stratifizierbar, if there is an image S of the set of predicates to the natural numbers satisfying the following conditions:

As an example, the following Prolog program is given:

P (x ) - q (x) q ( X): - not ( r ( X) ), s ( X, Z) is a possible stratification of this program.

- Mathematical Logic