Numerical analysis may produce vast amounts of numerical information which must be aggregated if it is to be interpreted.
Precise predictions require precise models which are often inaccurate.
Thus , qualitative approaches offer an accurate, if not precise description of the system behaviour. Outliers tend to have interesting properties, good or bad, or they may point to broken domain models or buggy software. As a result, Pret tries to discard models by purely qualitative means before resorting to numerical techniques. In Pret, every rule is explicitly assigned an abstraction level number. Similarly , the logic engine s dynamic control is used in Pret to guide the search toward a cheap and quick proof of falsum.