Rajeev Kumar, Romesh Kumar, Composition Operators on Banach Function Spaces, Proceedings of the American Mathematical Society, Vol. 133, No. 7 (Jul., 2005), pp. 2109-2118 ...

Composition Operator: An operator defined by composing functions with a fixed analytic mapping, often studied for its boundedness and compactness properties in various function spaces.

A comprehensive review in Nature Reviews Immunology concludes that evidence is mounting in clinical trials and other studies that the composition and function of individuals' gut microbiota are ...