 That means it lies in an algebraic set that is a finite union of algebraic varieties of dimension lower than "d", the dimension of "V".A type II thin set is an image of an algebraic morphism (essentially a polynomial mapping) φ, applied to the "K"-points of some other "d"-dimensional algebraic variety "V"′, that maps essentially onto "V" as a ramified covering with degree "e" > 1.Saying this more technically, a thin set of type II is any subset of

where "V"′ satisfies the same assumptions as "V" and φ is generically surjective from the geometer's point of view.