Observability from a measurable set for functions in a Gevrey class

Abstract We provide an observability inequality in terms of a measurable set for general Gevrey‐regular functions. As an application, we establish an observability estimate from a measurable set for sums of Laplace eigenfunctions in a compact and connected boundaryless Riemannian manifold that belongs to the Gevrey class. The estimate has an explicit dependence on the maximal eigenvalue.