Systems of fixed point sets
Systems of fixed point sets
复制标题
定点集系统
DOI:
10.1090/s0002-9947-1983-0690052-0
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发表时间:
1983
影响因子:
1.3
通讯作者:
A. Elmendorf
中科院分区:
文献类型:
--
作者:
A. Elmendorf
Let G be a compact Lie group. A canonical method is given for constructing a C-space from homotopy theoretic information about its fixed point sets. The construction is a special case of the categorical bar construction. Applications include easy constructions of certain classifying spaces, as well as C-EilenbergMac Lane spaces and Postnikov towers. 0. Introduction. Let G be a compact Lie group and X a G-space. The equivariant homotopy theory of X is reflected to a remarkable extent in its system of fixed point sets, defined as a functor from a certain category 0G to Top, the category of topological spaces. (Our spaces will be compactly generated weak Hausdorff; they may or may not be equipped with a basepoint, depending on the context.) These functors, or systems, have considerable technical advantages over G-spaces; it is easy to apply most homotopy theoretic constructions to them, whereas in many cases it is unclear how to proceed for G-spaces. It is the purpose of this paper to present a canonical way of recovering from any system a G-space which preserves all the homotopy theoretic structure of the system. This allows us to give easy equivariant versions of some standard topological constructions such as Eilenberg-Mac Lane spaces and Postnikov towers, and to simplify other equivariant constructions.1 1. Statements of the main theorems. Throughout, G is a fixed compact Lie group. Definitions. The category of canonical orbits, written 0G, is a topological category with discrete object space \0G\ = (G/77: 77 a closed subgroup of G} and morphisms the G-maps, topologized by requiring the natural bijection (•) Hoxn0ciG/H,G/K)^{G/K)H to be a homeomorphism. By an Oc-space we shall mean a continuous contravariant functor from 0G to Top; these functors form the objects of a topological category in the usual manner. We will also consider GG-rings, Oc-groups, etc., defined similarly. Definition. Let A1 be a G-space. The fixed point set system of X, written $X, is an GG-space defined as follows: $ *( G/77) = X", Received by the editors October 30, 1981 and, in revised form, April 26, 1982. 1980 Mathematics Subject Classification. Primary 57S10, 55N25.