Stable moduli spaces of odd-dimensional manifold triads
João Lobo Fernandes
TL;DR
This work extends the stable moduli-space program of Galatius and Randal-Williams to odd-dimensional manifold triads with fixed vertical boundary, introducing a boundary-connected-sum stabilization by $V_g$ and a Moore–Postnikov $n$-factorization framework for tangential data. The main result identifies the stabilized moduli space of $ abla$-structures on a triad with the homotopy orbit of the infinite-loop Thom spectrum $\mathbf{MT}\Theta_N$, via an acyclic map onto a path component of $\Omega^{\infty}\mathbf{MT}\Theta_N$. A Kreck-type stable classification for odd triads follows, linking stable diffeomorphism types to stable normal $n$-types and Euler characteristics. The paper develops a comprehensive cobordism-category toolkit with boundary, refined surgery arguments, and a group-completion strategy, culminating in a flexible general theorem for $\\Theta$-structures and a suite of examples, including reductions to existing even-dimensional results. Overall, the results provide a robust odd-dimensional analogue of the GRW program, with broad implications for the homotopy type of diffeomorphism classifying spaces and stable diffeomorphism classifications in the presence of boundary data.
Abstract
We establish a homotopy-theoretic description of the homology of stable moduli spaces of $(2n+1)$-dimensional manifold triads $(N, \partial^h N, \partial^v N)$ with fixed $\partial^v N$, whenever $n \geq 3$ and $(N, \partial^h N)$ is $1$-connected. Stabilization is performed by taking boundary connected sum with $S^n \times D^{n+1}$. This is an analog of earlier work of Galatius and Randal-Williams for even-dimensional manifolds with fixed boundary, and it extends a previous result by Botvinnik and Perlmutter. As a byproduct, we obtain an analog for odd-dimensional triads of Kreck's stable diffeomorphism classification of even-dimensional manifolds.
