Abstract
Simons and Sullivan constructed a model of differential K-theory, and showed that the differential K-theory functor fits into a hexagon diagram. They asked whether, like the case of differential characters, this hexagon diagram uniquely determines the differential K-theory functor. This article provides a partial affirmative answer to their question: For any fixed compact manifold, the differential K-theory groups are uniquely determined by the Simons–Sullivan diagram up to an isomorphism compatible with the diagonal arrows of the hexagon diagram. We state a necessary and sufficient condition for an affirmative answer to the full question. This approach further yields an alternative proof of a weaker version of Simons and Sullivan’s results concerning axiomatization of differential characters. We further obtain a uniqueness result for generalised differential cohomology groups. The proofs here are based on a recent work of Pawar.
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Notes
Our convention of degrees differs from the one in original paper [9] where this group is called \({\hat{H}}^{k-1}(M;{\mathbb {R}}/{\mathbb {Z}})\).
References
Arlin, K.: About functor category and enough injectives. Mathematics Stack Exchange. https://math.stackexchange.com/q/2460009 (version: 2017-10-06)
Bär, C., Becker, C.: Differential Characters and Geometric Chains, pp. 1–90. Springer International Publishing, Cham (2014). https://doi.org/10.1007/978-3-319-07034-6_1
Brylinski, J.L.: Loop Spaces, Characteristic Classes and Geometric Quantization, Modern Birkhäuser Classics, vol. 107. Birkhäuser, Basel (1993). https://doi.org/10.1007/978-0-8176-4731-5
Bunke, U., Kreck, M., Schick, T.: A geometric description of differential cohomology. Ann. Math. Blaise Pascal 17(1), 1–16 (2010). https://doi.org/10.5802/ambp.276
Bunke, U., Schick, T.: Smooth \(k\)-theory. In: Xianzhe, D., Rémi, L., Ma, X., Weiping, Z. (eds.): From probability to geometry (II)—volume in honor of the 60th birthday of Jean-Michel Bismut, no. 328 in Astérisque, pp. 45–135. Société Mathématique de France (2009). http://www.numdam.org/item/AST_2009__328__45_0
Bunke, U., Schick, T.: Uniqueness of smooth extensions of generalized cohomology theories. J. Topol. 3(1), 110–156 (2010). https://doi.org/10.1112/jtopol/jtq002
Bunke, U., Schick, T.: Differential k-theory: a survey. In: Bär, C., Lohkamp, J., Schwarz, M. (eds.) Global Differential Geometry, pp. 303–357. Springer, Berlin (2012)
Carey, A.L., Mickelsson, J., Wang, B.L.: Differential twisted K-theory and applications. J. Geom. Phys. 59(5), 632–653 (2009). https://doi.org/10.1016/j.geomphys.2009.02.00
Cheeger, J., Simons, J.: Differential characters and geometric invariants. Geometry and Topology, pp. 50–80. Springer, Berlin (1985)
Gajer, P.: Geometry of Deligne cohomology. Invent. Math. 127(1), 155–207 (1997). https://doi.org/10.1007/s002220050118
Harvey, R., Lawson, B.: From sparks to grundles—differential characters. Commun. Anal. Geom. 14(1), 25–58 (2006). https://doi.org/10.4310/CAG.2006.v14.n1.a2
Harvey, R., Lawson, B., Zweck, J.: The de Rham–Federer theory of differential characters and character duality. Am. J. Math. 125(4), 791–847 (2003). https://doi.org/10.1353/ajm.2003.0025
Hopkins, M., Singer, I.: Quadratic functions in geometry, topology, and m-theory. J. Differ. Geom. 70(3), 329–452 (2005). https://doi.org/10.4310/jdg/1143642908
Kübel, A., Thom, A.: Equivariant differential cohomology. Trans. Am. Math. Soc. 370, 8237–8283 (2018). https://doi.org/10.1090/tran/7315
Lin, Z.: Projectives and injectives in functor categories. MathOverflow. https://mathoverflow.net/q/162801 (version: 2016-01-23)
Mitchell, B.: A remark on projectives in functor categories. J. Algebra 69(1), 24–31 (1981). https://doi.org/10.1016/0021-8693(81)90124-1
Park, B.: Geometric models of twisted differential K-theory I. J. Homot. Relat. Struct. 13(1), 143–167 (2017). https://doi.org/10.1007/s40062-017-0177-z
Pawar, R.: A generalization of Grothendieck’s extension Panachées. Proc. Math. Sci. (2019). https://doi.org/10.1007/s12044-019-0523-7
Redden, C.: Differential Borel equivariant cohomology via connections. NY J. Math. 23, 441–487 (2017). http://nyjm.albany.edu/j/2017/23-20.html
Rotman, J.: An Introduction to Homological Algebra, 2 edn. Universitext. Springer, New York (2009). https://doi.org/10.1007/b98977. https://www.springer.com/gp/book/9780387245270
Simons, J., Sullivan, D.: Axiomatic characterization of ordinary differential cohomology. J. Topol. 1(1), 1–23 (2008). https://doi.org/10.1112/jtopol/jtm006
Simons, J., Sullivan, D.: Structured bundles define differential K-theory, pp. 1–12. https://arxiv.org/abs/0810.4935
Simons, J., Sullivan, D.: The Mayer–Vietoris property in differential cohomology (2010). https://arxiv.org/abs/1010.5269
Weibel, C.A.: An Introduction to Homological Algebra. Cambridge Studies in Advanced Mathematics, Cambridge University Press, Cambridge https://doi.org/10.1017/CBO9781139644136 (1994)
Acknowledgements
I wish to thank my supervisor Dr. Rishikesh Vaidya for discussions and support. I am thankful to Jitendra Rathore for valuable discussions. Prof. Dennis Sullivan kindly shared his feedback and comments on the pre-print version of this article arXiv:2005.02056, I feel thankful to him. I wish to profusely thank an anonymous expert for several comments which helped improve the results herein, especially for pointing out that the method herein applies to the case of generalised differential cohomology theories as well. An anonymous reviewer gave valuable suggestions which helped me improve the presentation, and pointed out some typos. Part of this work was carried out while I was financially supported by the Council of Scientific and Industrial Research under the CSIR-SRF(NET) scheme.
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Mata, I. Uniqueness of differential characters and differential K-theory via homological algebra. J. Homotopy Relat. Struct. 16, 225–243 (2021). https://doi.org/10.1007/s40062-021-00278-4
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DOI: https://doi.org/10.1007/s40062-021-00278-4