Task: Text Categorization
Input (English): Hadamard regularized this operation under certain conditions by dropping divergent terms. Measure theory is used in Lebesgue's [le-bays] theory of this operation, and Fubini's theorem states that its order in iterated versions can be changed. For products of functions, this operation is often done(*) "by parts." Simpson's Rule approximates this process using trapezoids, while Bernhard Riemann devised a method using rectangles. The "definite" kind of this process finds the area under a curve. For 10 points, name this mathematical technique, the opposite of differentiation.
Output (English): Social Science