For 10 points, name this mathematical technique, the opposite of differentiation.
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.
Hadamard regularized this operation under certain conditions by dropping divergent terms.
{integration} [or word forms such as {integrable} or {integrate} or taking the{ integral}; or “Lebesgue {integration}”, or “Riemann {integration},” or “definite {integration}”; or “indefinite {integration},” “primitive {integration},” “{antiderivative},” or “{antidifferentiation}” before “Simpson’s”]