Goussarov-Polyak-Viro type formulas for $(4k-1)$-dimensional knots and links in $\mathbb{R}^{6k}$

Abstract

We produce combinatorial formulas for invariants of smooth embeddings of $(2\ell-1)$-spheres into $\mathbb{R}^{3\ell}$ for $\ell\geq 2$. Furthermore, we obtain such a formula for the Haefliger invariant, which classifies smooth knots $S^{4k-1}\hookrightarrow \mathbb{R}^{6k}$ up to isotopy. Our approach is similar in spirit to the work of Goussarov, Polyak, and Viro expressing finite-type invariants of classical knots in terms of Gauss diagrams. We similarly project higher dimensional knots and links onto a hyperplane and study the preimages of the sets of double and singular points in the embedded spheres. As an auxiliary result, we show that the space of $n$-dimensional braids with $k$ strands in $\mathbb{R}^{n+q}$ is a homotopy retract of the space of long links $\underset{k}{\sqcup}\mathbb{R}^n\hookrightarrow\mathbb{R}^{n+q}$ for $q\geq 3$, thus proving a conjecture of Komendarczyk, Koytcheff and Voli\'c.