Some examples of first exit times
The purpose of this article is to compute the expected first exit times of Brownian motion from a variety of domains in the Euclidean plane and in the hyperbolic plane.
math.DG↗
arXiv subjects
Alberto Candel
Publications and source records attributed to Alberto Candel.
Non-reduction of relations in the Gromov space to Polish actions
It is shown that, in the Gromov space of isometry classes of pointed proper metric spaces, the equivalence relations defined by existence of coarse quasi-isometries or being at finite Gromov-Hausdorff distance, cannot be reduced to the equivalence relation defined by any Polish action.
math.GT↗
A universal Riemannian foliated space
It is proved that the isometry classes of pointed connected complete Riemannian $n$-manifolds form a Polish space, $\mathcal{M}_*^\infty(n)$, with the topology described by the $C^\infty$ convergence of manifolds. This space has a canonical partition into sets defined by varying the distinguished point into each manifold. The locally non-periodic manifolds define an open dense subspace $\mathcal{M}_{*,\text{lnp}}^\infty(n)\subset\mathcal{M}_*^\infty(n)$, which becomes a $C^\infty$ foliated space with the restriction of the canonical partition. Its leaves without holonomy form the subspace $\mathcal{M}_{*,\text{np}}^\infty(n)\subset\mathcal{M}_{*,\text{lnp}}^\infty(n)$ defined by the non-periodic manifolds. Moreover the leaves have a natural Riemannian structure so that $\mathcal{M}_{*,\text{lnp}}^\infty(n)$ becomes a Riemannian foliated space, which is universal among all sequential Riemannian foliated spaces satisfying certain property called covering-continuity. $\mathcal{M}_{*,\text{lnp}}^\infty(n)$ is used to characterize the realization of complete connected Riemannian manifolds as dense leaves of covering-continuous compact sequential Riemannian foliated spaces.
math.GT↗
Generic coarse geometry of leaves
A compact Polish foliated space is considered. Part of this work studies coarsely quasi-isometric invariants of leaves in some residual saturated subset when the foliated space is transitive. In fact, we also use "equi-" versions of this kind of invariants, which means that the definition is satisfied with the same constants by some given set of leaves. For instance, the following properties are proved. Either all dense leaves without holonomy are equi-coarsely quasi-isometric to each other, or else there exist residually many dense leaves without holonomy such that each of them is coarsely quasi-isometric to meagerly many leaves. Assuming that the foliated space is minimal, the first of the above alternatives holds if and if the leaves without holonomy satisfy a condition called coarse quasi-symmetry. A similar dichotomy holds for the growth type of the leaves, as well as an analogous characterization of the first alternative in the minimal case, involving a property called growth symmetry. Moreover some classes of growth are shared, either by residually many leaves, or by meagerly many leaves. If some leaf without holonomy is amenable, then all dense leaves without holonomy are equi-amenable, and, in the minimal case, they satisfy a property called amenable symmetry. Residually many leaves have the same asymptotic dimension. If the foliated space is minimal, then any pair of nonempty open sets in the Higson coronas of the leaves with holonomy contain homeomorphic nonempty open subsets. Another part studies limit sets of leaves at points in their Higson corona, defined like the usual limit sets at their ends.
math.GT↗
Algebraic characterization of quasi-isometric spaces via the Higson compactification
The purpose of this article is to characterize the quasi-isometry type of a proper metric space via the Banach algebra of Higson functions on it.
math.MG↗
Equicontinuous foliated spaces
Some properties of Riemannian foliations on closed manifolds are generalized to compact equicontinuous foliated spaces. For instance, it is proved that all holonomy covers of the leaves are quasi-isometric to each other.
math.GT↗
Topological description of Riemannian foliations with dense leaves
A transitive compact foliated space is shown to be a Riemannian foliation if and only if it is locally connected, finite dimensional, strongly equicontinuous and quasi-analytic, and the closure of its holonomy pseudogroup is quasi-analytic.
math.GT↗
On turbulent relations
This paper extends the theory of turbulence of Hjorth to certain classes of equivalence relations that cannot be induced by Polish actions. It applies this theory to analyze the quasi-isometry relation and finite Gromov-Hausdorff distance relation in the space of isometry classes of pointed proper metric spaces, called the Gromov space.
math.LO↗