A degeneracy bound for homogeneous topological order

We introduce a notion of homogeneous topological order, which is obeyed by most, if not all, known examples of topological order including fracton phases on quantum spins (qudits). The notion is a condition on the ground state subspace, rather than on the Hamiltonian, and demands that given a collection of ball-like regions, any linear transformation on the ground space be realized by an operator that avoids the ball-like regions. We derive a bound on the ground state degeneracy \mathcal D𝒟 for systems with homogeneous topological order on an arbitrary closed Riemannian manifold of dimension dd, which reads [ D c (L/a)^{d-2}.] Here, LL is the diameter of the system, aa is the lattice spacing, and cc is a constant that only depends on the isometry class of the manifold, and \muμ is a constant that only depends on the density of degrees of freedom. If d=2d=2, the constant cc is the (demi)genus of the space manifold. This bound is saturated up to constants by known examples.examples.

Ricci-Bourguignon flow coupled with harmonic map flow

In this paper, we study a coupled system of the Ricci–Bourguignon flow on a closed Riemannian manifold [Formula: see text] with the harmonic map flow. At the first, we will investigate the existence and uniqueness for solution of this flow on a closed Riemannian manifold and then we find evolution of some geometric structures of manifold along this flow.

Convergence of the solutions of discounted Hamilton–Jacobi systems

We consider a weakly coupled system of discounted Hamilton–Jacobi equations set on a closed Riemannian manifold. We prove that the corresponding solutions converge to a specific solution of the limit system as the discount factor goes to 0. The analysis is based on a generalization of the theory of Mather minimizing measures for Hamilton–Jacobi systems and on suitable random representation formulae for the discounted solutions.

Volumes of balls in Riemannian manifolds and Uryson width

If [Formula: see text] is a closed Riemannian manifold where every unit ball has volume at most [Formula: see text] (a sufficiently small constant), then the [Formula: see text]-dimensional Uryson width of [Formula: see text] is at most 1.

Volume of minimal hypersurfaces in manifolds with nonnegative Ricci curvature

We establish a min-max estimate on the volume width of a closed Riemannian manifold with nonnegative Ricci curvature. More precisely, we show that every closed Riemannian manifold with nonnegative Ricci curvature admits a PL Morse function whose level set volume is bounded in terms of the volume of the manifold. As a consequence of this sweep-out estimate, there exists an embedded, closed (possibly singular) minimal hypersurface whose volume is bounded in terms of the volume of the manifold.

Semiclassical states for a static supercritical Klein–Gordon–Maxwell–Proca system on a closed Riemannian manifold

We establish the existence of semiclassical states for a nonlinear Klein–Gordon–Maxwell–Proca system in static form, with Proca mass [Formula: see text] on a closed Riemannian manifold. Our results include manifolds of arbitrary dimension and allow supercritical nonlinearities. In particular, we exhibit a large class of three-dimensional manifolds on which the system has semiclassical solutions for every exponent [Formula: see text] The solutions we obtain concentrate at closed submanifolds of positive dimension as the singular perturbation parameter goes to zero.

Singular equivariant asymptotics and Weyl’s law. On the distribution of eigenvalues of an invariant elliptic operator

We study the spectrum of an invariant, elliptic, classical pseudodifferential operator on a closed Riemannian manifold

Epsilon Nielsen coincidence theory

We construct an epsilon coincidence theory which generalizes, in some aspect, the epsilon fixed point theory proposed by Robert Brown in 2006. Given two maps f, g: X → Y from a well-behaved topological space into a metric space, we define µ ∈(f, g) to be the minimum number of coincidence points of any maps f 1 and g 1 such that f 1 is ∈ 1-homotopic to f, g 1 is ∈ 2-homotopic to g and ∈ 1 + ∈ 2 < ∈. We prove that if Y is a closed Riemannian manifold, then it is possible to attain µ ∈(f, g) moving only one rather than both of the maps. In particular, if X = Y is a closed Riemannian manifold and idY is its identity map, then µ ∈(f, idY) is equal to the ∈-minimum fixed point number of f defined by Brown. If X and Y are orientable closed Riemannian manifolds of the same dimension, we define an ∈-Nielsen coincidence number N ∈(f, g) as a lower bound for µ ∈(f, g). Our constructions and main results lead to an epsilon root theory and we prove a Minimum Theorem in this special approach.