“…Recent work of Mustaţǎ [35] supports these predictions by showing that the arc spaces contain information about singularities, for example rational singularities of X can be detected by the irreducibility of the jet schemes for complete intersections. In subsequent investigations he and his collaborators show that certain invariants of birational geometry, such as the log canonical threshold of a pair, for example, can be read off from the dimensions of certain components of the jet schemes, see [36,15,17] and Section 5 where we will discuss some of these results in detail. Let X be a (smooth) scheme of finite type over k of dimension n. An m-jet of X is an order m infinitesimal curve in X , i.e.…”