Relative Lubin-Tate groups
Relative Lubin-Tate groups
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相对鲁宾-泰特组
DOI:
10.1090/s0002-9939-1985-0796434-8
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发表时间:
1985
期刊:
影响因子:
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通讯作者:
E. D. Shalit
中科院分区:
文献类型:
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作者:
E. D. Shalit
We construct a class of formal groups that generalizes LubinTate groups. We formulate the major properties of these groups and indicate their relation to local class field theory. The aim of this note is to introduce a certain family of formal groups generalizing Lubin-Tate groups. Although the construction, basic properties and relation with local class field theory are all similar to Lubin-Tate theory, the author is unaware of previous references to these groups. We remark, however, that they are complementary in some sense to the formal groups studied by Honda in [2]. Since we want to keep this note short, all the proofs are omitted. The reader who is acquainted with Lubin-Tate theory as in [4 or 5] will be able to supply them without any difficulties. I would like to acknowledge my debt to K. Iwasawa. His beautiful exposition of local class field theory [3] motivated this note. 1. Let k be a finite extension of Qp, v: kx -Z the normalized valuation (normalized in the sense that v(kX) = Z), 0 and p its ring of integers and maximal ideal, and k = 0/ the residue field, a finite field of characteristics p and q elements. kalg denotes an algebraic closure of k and kUr the maximal unramified extension of k in it. We also fix a completion of kalg, Q, and let K be the closure of k"r in it. We write (p for the Frobenius automorphism of kur/k, characterized by p(x) = mod pur, for all x E Our. It extends by continuity to an automorphism of K/k, still denoted by p. If k' is another finite extension of Qp, the corresponding objects will be denoted by ', e.g. (p', q', etc. If A is any ring, A[[X,... ., Xn]] will denote the power series ring in Xi. If f and g are elements of it, f -g mod deg m means that the power series f g involves only monomials of degree at least m. 2. Fix the field k. For each integer d let Ed be the set of all ( E k, v(s) = d. Fix also d > 0 and let k' be the unique unramified extension of k of degree d. Let E Ed and consider = {f E 0'[[X]]If _ 7r'Xmoddeg2, Nk,/k(1r') = ( and f-Xq mod O'}. THEOREM 1. For each f E 7e there is a unique one-dimensional commutative formal group law Ff E 0'[[X, Y]] satisfying FJ' o f = f o Ff. In others words, f is a homomorphism of Ff to Fr. Received by the editors March 2, 1984. 1980 Mathematics Subject Claification. Primary 12B25.