In mathematics, in the field of harmonic analysis, the van der Corput lemma is an estimate for oscillatory integrals named after the Dutch mathematician J. G. van der Corput.
The following result is stated by E. Stein:
Suppose that a real-valued function
for any
Sublevel set estimates
The van der Corput lemma is closely related to the sublevel set estimates (see for example ), which give the upper bound on the measure of the set where a function takes values not larger than
Suppose that a real-valued function