932 research outputs found

    Mixed motivic sheaves (and weights for them) exist if 'ordinary' mixed motives do

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    The goal of this paper is to prove: if certain 'standard' conjectures on motives over algebraically closed fields hold, then over any 'reasonable' SS there exists a motivic tt-structure for the category of Voevodsky's SS-motives (as constructed by Cisinski and Deglise). If SS is 'very reasonable' (for example, of finite type over a field) then the heart of this tt-structure (the category of mixed motivic sheaves over SS) is endowed with a weight filtration with semi-simple factors. We also prove a certain 'motivic decomposition theorem' (assuming the conjectures mentioned) and characterize semi-simple motivic sheaves over SS in terms of those over its residue fields. Our main tool is the theory of weight structures. We actually prove somewhat more than the existence of a weight filtration for mixed motivic sheaves: we prove that the motivic tt-structure is transversal to the Chow weight structure for SS-motives (that was introduced previously and independently by D. Hebert and the author; weight structures and their transversality with t-structures were also defined by the author in recent papers). We also deduce several properties of mixed motivic sheaves from this fact. Our reasoning relies on the degeneration of Chow-weight spectral sequences for 'perverse 'etale homology' (that we prove unconditionally); this statement also yields the existence of the Chow-weight filtration for such (co)homology that is strictly restricted by ('motivic') morphisms.Comment: a few minor corrections mad

    Relative continuous K-theory and cyclic homology

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    We show that for an associative algebra A and its ideal I such that the I-adic topology on A coincides with the p-adic topology, the relative continuous K-theory pro-spectrum "lim"K(A_i, IA_i), where A_i :=A/p^i A, is naturally isogenous to the cyclic chain pro-complex "lim"CC(A_i) (subject to minor conditions on A). This identification is a continuous version of the classical Goodwillie isomorphism. The work comes from an attempt to understand the article of Bloch, Esnault, and Kerz "p-adic deformations of algebraic cycle classes".Comment: 26 pages. The section about pro-spectra is corrected. To appear in the Munster Journal of Mathematic
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