safe

A safe program analysis is one which will not reach invalid

conclusions about the behaviour of the program. This may

involve making safe approximations to properties of parts of

the program. A safe approximation is one which gives less

information.

For example, strictness analysis aims to answer the question

"will this function evaluate its argument"?. The two possible

results are "definitely" and "don't know". A safe

approximation for "definitely" is "don't know". The two

possible results correspond to the two sets: "the set of all

functions which evaluate their argument" and "all functions".

A set can be safely approximated by another which contains it.