Gevrey class
In mathematics, the Gevrey class Gσ, introduced by, consists of the smooth functions g on Rn such that on every compact subset K there are constants C and R with
for multi-indices α, such that |α| = k, and corresponding differential operators Dα ; and x restricted to lie in the compact set K.
When σ = 1 this class is the same as the class of analytic functions. For σ > 1 there are compactly supported functions in the class that are not identically zero.
