A concept which has proved useful in the study of measures is tameness.
These results show that an analysis purely at the level of functions cannot be useful for describing ......
This assumption is useful for simplifying proofs.
The following variant of Theorem 2 is occasionally useful.
This is the least useful of the four theorems.
At times [= Occasionally] it will be useful to consider ......
It is useful to consider some rather simple examples to gain some intuition.
These idempotents provide a useful tool for analysing the structure of $G$.