Associated to a discrete group G, one has the topological category of finite dimensional (unitary) G–representations and (unitary) isomorphisms. Block sums provide this category with a permutative structure, and the associated K–theory spectrum is Carlsson’s deformation K–theory Kdef(G). The goal of this paper is to examine the behavior of this functor on free products. Our main theorem shows the square of spectra associated to G∗H (considered as an amalgamated product over the trivial group) is homotopy cartesian. The proof uses a general result regarding group completions of homotopy commutative topological monoids, which may be of some independent interest.
Ramras, Daniel  1
@article{10_2140_agt_2007_7_2239,
author = {Ramras, Daniel},
title = {Excision for deformation {K{\textendash}theory} of free products},
journal = {Algebraic and Geometric Topology},
pages = {2239--2270},
year = {2007},
volume = {7},
number = {4},
doi = {10.2140/agt.2007.7.2239},
url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2007.7.2239/}
}
Ramras, Daniel. Excision for deformation K–theory of free products. Algebraic and Geometric Topology, Tome 7 (2007) no. 4, pp. 2239-2270. doi: 10.2140/agt.2007.7.2239
[1] , Notes: $PSL_2(\mathbb{Z}) = \mathbb{Z}_2*\mathbb{Z}_3$, Amer. Math. Monthly 100 (1993) 385
[2] , Characters and cohomology of finite groups, Inst. Hautes Études Sci. Publ. Math. (1961) 23
[3] , , Equivariant $K$–theory and completion, J. Differential Geometry 3 (1969) 1
[4] , Derived representation theory and the algebraic $K$–theory of fields (2003)
[5] , , Calculus of fractions and homotopy theory, Ergebnisse der Mathematik und ihrer Grenzgebiete 35, Springer (1967)
[6] , Algebraic topology, Cambridge University Press (2002)
[7] , Triangulations of algebraic sets, from: "Algebraic geometry (Proc. Sympos. Pure Math., Vol. 29, Humboldt State Univ., Arcata, CA, 1974)" (editor R Hartshorne), Amer. Math. Soc. (1975) 165
[8] , Derived Representation Theory of Nilpotent Groups, PhD thesis, Stanford University (2004)
[9] , The Bott cofiber sequence in deformation $K$–theory (2006)
[10] , The spectra associated to permutative categories, Topology 17 (1978) 225
[11] , , Homology fibrations and the “group-completion” theorem, Invent. Math. 31 (1975/76) 279
[12] , Yang–Mills theory over surfaces and the Atiyah–Segal theorem
[13] , Stable Representation Theory of Infinite Discrete Groups, PhD thesis, Stanford University (2007)
[14] , Classifying spaces and spectral sequences, Inst. Hautes Études Sci. Publ. Math. (1968) 105
[15] , Categories and cohomology theories, Topology 13 (1974) 293
[16] , Elementary structure of real algebraic varieties, Ann. of Math. $(2)$ 66 (1957) 545
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