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

Tadayuki Watanabe

This paper studies the rational homotopy groups of the group $\mathrm{Diff}(S^4)$ of self-diffeomorphisms of $S^4$ with the $C^{\infty }$-topology. We present a method to prove that t…