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Some exotic nontrivial elements of the rational homotopy groups of $Diff(S^4)$

. (2018)cite arxiv:1812.02448Comment: 74 pages, 27 figures. Added Appendix B.

Abstract

This paper studies the rational homotopy groups of the group $Diff(S^4)$ of self-diffeomorphisms of $S^4$ with the $C^ınfty$-topology. We present a method to prove that there are many `exotic' non-trivial elements in $\pi_*Diff(S^4)Q$ parametrized by trivalent graphs. As a corollary of the main result, the 4-dimensional Smale conjecture is disproved. The proof utilizes Kontsevich's characteristic classes for smooth disk bundles and a version of clasper surgery for families. In fact, these are analogues of Chern--Simons perturbation theory in 3-dimension and clasper theory due to Goussarov and Habiro.

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Some exotic nontrivial elements of the rational homotopy groups of $\mathrm{Diff}(S^4)$

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