Algebraic Jf-theory and Trace Invariants
Algebraic Jf-theory and Trace Invariants
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代数 Jf 理论和迹不变量
DOI:
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发表时间:
2003
期刊:
影响因子:
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通讯作者:
L. Hesselholt
中科院分区:
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作者:
L. Hesselholt
The cyclotomic trace of Bokstedt-Hsiang-Madsen, the subject of Bokstedt's lecture at the congress in Kyoto, is a map of pro-abelian groups K-fiA) ^.TR;(A;p) from Quillen's algebraic A"-theory to a topological refinement of Connes' cyclic homology. Over the last decade, our understanding of the target and its relation to A"-theory has been significantly advanced. This and possible future development is the topic of my lecture. The cyclotomic trace takes values in the subset fixed by an operator F called the Frobenius. It is known that the induced map K*(A,Z/pv) -^ TR;(A;P,Z/PV)F=1 is an isomorphism, for instance, if A is a regular local Fp-algebra, or if A is a henselian discrete valuation ring of mixed characteristic (0,p) with a separably closed residue field. It is possible to evaluate A"-theory by means of the cyclotomic trace for a wider class of rings, but the precise connection becomes slightly more complicated to spell out. The pro-abelian groups TR*(A;p) are typically very large. But they come equipped with a number of operators, and the combined algebraic structure is quite rigid. There is a universal example of this structure — the de Rham-Witt complex — which was first considered by Bloch-Deligne -Illusie in connection with Grothendieck's crystalline cohomology. In general, the canonical map W.QqA^TR-q(A-p) is an isomorphism, if q < 1, and the higher groups, too, can often be expressed in terms of the de Rham-Witt groups. This is true, for example, if A is a regular Fp-algebra, or if A is a smooth algebra over the ring of integers in a local number field. The calculation in the latter case verifies the LichtenbaumQuillen conjecture for focal number fields, or more generally, for henselian discrete valuation fields of geometric type.