Derivative of volumes of big cohomology classes (2307.15909v1)

Abstract: We prove that the partial derivative of the volume function of big classes along any real divisor in a compact Kaehler manifold is equal to the numerical restricted volume of that class to the divisor. A consequence of our main result is that the divisorial components of the non-Kaehler locus of a big class lie in fact in the null locus of that class.