“…[5], or, to pick some examples from Geneviève Raugel's work: [26, (2.21)], [27, (6.14), (8.15)], [15, proof of (2.32)]). Various extensions of the classical GNI are available, for instance: It has been studied in Besov spaces ( [21,22]), on Riemannian manifolds ( [4,6]), with a BMO term ( [8,28,20,29,23]), in Orlicz spaces ( [17,18,16]), for noninteger derivatives ( [24]), with weighted ( [10]) and anisotropic ( [11]) terms, and extremal functions and optimal constants have been determined ( [30,9,3,1,19]). For a relation with mass transport theory see [7,2].…”