文摘
Let k be a field of characteristic zero, and let X be a projective variety embedded into a projective space over k. For two natural numbers r and d let \(C_{r,d}(X)\) be the Chow scheme parametrizing effective cycles of dimension r and degree d on the variety X. Choosing an r-cycle of minimal degree gives rise to a chain of embeddings of Chow schemes, whose colimit is the connective Chow monoid \({C}_r^{\infty }(X)\) of r-cycles on X. Let be the classifying motivic space of this monoid. In the paper we establish an isomorphism between the Chow group of degree 0 dimension r algebraic cycles modulo rational equivalence on X, and the group of sections of the Nisnevich sheaf of \({\mathbb {A}^{1}}\)-path connected components of the loop space of at \({{\mathrm{Spec}}(k)}\). Equivalently, is isomorphic to the group of sections of the stabilized motivic fundamental group at \({{\mathrm{Spec}}(k)}\). Keywords Algebraic cycles Chow monoids Group completion Nisnevich sheaves (Motivic) homotopy category Bousfield localization Loop functor Classifying spaces \({\mathbb {A}^{1}}\)-homotopy groups