On the integral simplicial volume of cyclic covers of mapping tori
Federica Bertolotti, Ervin Hadziosmanovic
TL;DR
The paper analyzes the asymptotics of the integral simplicial volume for cyclic covers of torus-fibered mapping tori, introducing the integral filling volume $FV_{\mathbb{Z}}$ as the limiting growth rate of mapping-torus covers. It establishes a tight link between this growth and the monodromy via the spectral radius $\rho(f_*)$ on $H_1(T^n;\mathbb{R})$, giving a universal bound $\frac{1}{K_n}\log\rho(f_*) \le \lim_{k\to\infty} \frac{\lVert (T^n)_{f^k}\rVert_{\mathbb{Z}}}{k} \le K_n\log\rho(f_*)$ with a dimension-two refinement. The upper bound in dimension two is achieved by constructing efficient fillings from parallelogram-like and rectangle-like cycles, culminating in a key bound that ties $\lVert f^k_*(c_n)-c_n \rVert_{\text{fill},\mathbb{Z}}$ to $\log\rho(A)$ via the Gelfand formula. The lower bound leverages torsion growth in first homology of mapping tori and Smith normal form to relate growth to eigenvalues of the monodromy, yielding a general inequality that applies beyond torus fibers. Applications connect $FV_{\mathbb{Z}}$ to topological entropy, provide new non-equivalences between $\Delta$-complexity and integral simplicial volume, and demonstrate the positive filling volume for Anosov diffeomorphisms on infranilmanifolds, enriching the understanding of how algebraic dynamics governs topological complexity.
Abstract
In this paper, we investigate the asymptotic behavior of the integral simplicial volume of cyclic covers of manifolds that fiber over the circle with fiber given by an $n$-dimensional torus. By studying the integral filling volume -- an invariant introduced by Frigerio and the first author -- for the monodromy, we establish both lower and upper bounds for the limit of the integral simplicial volume of these covers, normalized by the degree of the covering. These bounds are expressed in terms of the action of the monodromy on the real homology of the fiber. As applications, we establish a close connection between the topological entropy and the integral filling volume of self-homeomorphisms of $n$-dimensional tori, we find new examples for which the Delta-complexity and the integral simplicial volume are not equivalent, and we prove the nonvanishing of the filling volume for Anosov self-diffeomorphisms of infranilmanifolds.
