Pontryagin duality for topological modules
Pontryagin duality for topological modules
复制标题
拓扑模块的庞特里亚金对偶性
DOI:
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发表时间:
1979
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影响因子:
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通讯作者:
J. Flood
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文献类型:
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作者:
J. Flood
A Pontryagin duality for topological modules over any locally compact ring is described, using the Pontryagin dual of the ring as character module. Several authors have attempted to extend the Pontryagin duality for locally compact Abelian groups to classes of topological modules over topological rings. G. C. Preston [6] obtained duality for modules over the />-adic integers and fields and their local products, M. F. Smith [7] for linear spaces, and M. D. Levin [4] for modules over discrete commutative rings. In each case, the character module, or module representing the contravariant dual functor, was taken to be the Pontryagin dual of the ring R, which was shown to be canonically an R-module. It is proven that duality holds for locally compact modules over locally compact rings, using the dual R of R as character module. A duality is valuable, in that it increases the possibilities for structural dismemberment of objects, and enhances the functional richness of the category under consideration. Parts of the result have been hinted at in the folklore of topological rings, where Kaplansky [3] and others have elegantly used characters to obtain structure theorems. A few obvious applications are included. 1. Suppose A and Y are objects in Top, the category of topological spaces and continuous functions. Denote by (A, Y) the space of continuous functions from A to Y given the compact-open topology. Then a subbasis for this topology is given by the sets U(K, O) = {/|/(A) c O}, where K is any compact subset of A and O a member of any subbasis for the topology of Y. The map X X Y -> (A, Y) is the action on objects of a functor from Topop X Top to Top [5, p. 181]. A well-known property of the compact-open topology gives a 1-1 correspondence between continuous functions A -» (A, Y) and functions from A x X to Y continuous on sets of the form A X K, where A is a locally compact subset of A. Another property is the following: 2. Lemma. Suppose ip: X X Y -» Z is in Top, and A is a topological space. The natural mappings (i) Af. X X (A, Y)^(A, Z), where ^(x,/)(a) = *(x,fia)) and Received by the editors May 10, 1978 and, in revised form, November 1, 1978. AMS (MOS) subject classifications (1970). Primary 22D35, 13J99. © 1979 American Mathematical Society OOO2-9939/79/00O0-0328/$02.2S 329 License or copyright restrictions may apply to redistribution; see https://www.ams.org/journal-terms-of-use