Task: Text Categorization
Input (English): According to Fubini's theorem, the order in which this operation is performed does not matter. The surface variety forms the basis of the divergence theorem, while the line form of this operation can be calculated with Green's theorem. If one of their bounds is positive or negative infinity, they are known as improper. Depending on whether or not their endpoints are defined, they can be either definite or indefinite, and they can be approximated using Riemann's sum. For 10 points, name this operation in calculus which can be used to find the area under a curve.
Output (English): Science