The holonomy Lie $\infty$-groupoid of a singular foliation I

Abstract: We construct a finite-dimensional higher Lie groupoid integrating a singular foliation $\mathcal F$, under the mild assumption that the latter admits a geometric resolution. More precisely, a recursive use of bi-submersions, a tool coming from non-commutative geometry and invented by Androulidakis and Skandalis, allows us to integrate any universal Lie $\infty$-algebroid of a singular foliation to a Kan simplicial manifold, where all components are made of non-connected manifolds which are all the same finite dimension that can be chosen to be equal to the ranks of a given geometric resolution. Its 1-truncation is the Androulidakis-Skandalis holonomy groupoid.