Multizeta in function field arithmetic
Multizeta in function field arithmetic
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函数域算术中的Multizeta
DOI:
10.4171/198-1/9
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发表时间:
2020
期刊:
影响因子:
--
通讯作者:
D. Thakur
中科院分区:
文献类型:
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作者:
D. Thakur
Euler’s multizeta values have been pursued recently again with renewed interest because of their emergence, for example in Grothendieck-Ihara program to study the absolute Galois group through the fundamental group of projective line minus three points and related studies of iterated extensions of Tate motives. Two types of multizeta were defined [T04, Sec 5.10] for function fields, one complex valued (generalizing Artin-Weil zeta function) and the other with values in Laurent series over finite fields (generalizing Carlitz zeta values). For the Fq Œt ! case, the first type was completely evaluated in [T04] (see [M06] for more detailed study in the higher genus case). We focus on the second analog in this report. In contrast to the classical division between the convergent versus the divergent (normalized) values, all the values are convergent in our case. In place of the sum or the integral shuffle relations, we have different kinds of relations: the shuffle type relations with Fp-coefficients and the relations with Fp.t/-coefficients. (Classically, of course, there is no such distinction, the rational number field being the prime field in that case). The first kind of relations have been understood (though not with a satisfying structural description) and show that the product of multizeta values can also be expressed as a sum of some multizeta values, so that the Fp-span of all multizeta values is an algebra. While [T09, Lr09, Lr10] conjectured and proved, in the special case A D FqŒt !, many such interesting relations, combinatorially quite involved to describe unlike the classical case, the proofs [T10] give the existence directly (for generalA, defined below) rather than proving those conjectures. We only have examples of second kind of relations so far. As for the analogs of interconnections mentioned in the first paragraph, we can connect to absolute Galois group (through analog of Ihara power series [ATp]) and fundamental group approach in the Grothendieck-Ihara program only through the mixed motives [A86, AT09]. We describe some of these motivic aspects and relation with recent work of V. Lafforgue and L. Taelman.