Generalizes Bestvina's Z-boundaries to coarse Z-boundaries.
problem Establishing properties of Z-boundaries for groups. method Introducing a new concept of a 'coarse Z-boundary' and proving theorems about it. result Admitting a coarse Z-boundary is a pure quasi-isometry invariant. In the previous work ([14]) we introduced the well-posed boundary conditions P−,L0 and P+,L1 for the odd signature operator to define the refined analytic torsion on a compact manifold with boundary. In this paper we discuss the gluing formula of the refined…
Study on magnetic field and potential systems to prove rigidity results.
problem Proving rigidity for magnetic field and potential systems.
method Explicit relation between ray transform and magnetic one, applying results from [DPSU07].
result Existence of a generic set of simple MP-systems with the same boundary action function must be k-gauge equivalent.
Characterizes relative hyperbolicity using Morse and contracting boundaries.
problem Understanding relative hyperbolicity in groups.
method Boundary-theoretic characterization using Morse and contracting boundaries.
result Non-elementary relatively hyperbolic groups have non-empty and compact Morse or contracting boundaries.
We study the boundary rigidity problem for compact Riemannian manifolds with boundary (M,g): is the Riemannian metric g uniquely determined, up to an action of diffeomorphism fixing the boundary, by the distance function ρg(x,y) known for all boundary points x and y? We prove in this paper global uniqueness …
The study examines stationary surfaces with boundaries and their properties.
problem Investigating stationary surfaces with boundaries and their critical points.
method A generalized bending energy functional is considered, and the first variation is computed. Boundary-value problems are examined, and a characterization of free-boundary surfaces is given.
result Characterization of free-boundary surfaces with rotational symmetry for scaling-invariant functionals.
Compact hypersurfaces minimize area in convex cones with free boundary.
problem Finding compact hypersurfaces minimizing area in convex cones with free boundary.
method Minimizing an anisotropic area functional under a volume constraint.
result Compact hypersurfaces are contained in a Wulff-shape.
On a smooth complete Riemannian spin manifold with smooth compact boundary, we demonstrate that the Atiyah-Singer Dirac operator DB in L2 depends Riesz continuously on L∞ perturbations of local boundary conditions B. The Lipschitz bound for the map ${…
Minimal crystallizations bound for 3-manifolds with boundary.
problem Bounding the gem-complexity of 3-manifolds with boundary.
method Proving bounds on gem-complexity and using crystallization properties.
result Sharp bounds for gem-complexity of 3-manifolds with boundary.
Let M be a moduli space of polystable rank 2-bundles bundles with fixed determinant (a moduli space of PU(2)-instantons) on a Gauduchon surface with pg=0 and b1=1. We study the holomorphic structure of M around a circle T of regular reductions. Our model space is a "…
We study realizations of pseudodifferential operators acting on sections of vector-bundles on a smooth, compact manifold with boundary, subject to conditions of Atiyah-Patodi-Singer type. Ellipticity and Fredholm property, compositions, adjoints and self-adjointness of such realizations are discussed. We construct regu…
In this paper we study the boundary at infinity of the curve complex C(S) of a surface S of finite type and the relative Teichmüller space Tel(S) obtained from the Teichmüller space by collapsing each region where a simple closed curve is short to be a set of diameter 1. C(S) an…
Researchers solve boundary and scattering rigidity problems for magnetic systems.
problem Recovering magnetic systems from boundary or scattering data.
method Reduced to magnetic systems and applied results from [DPSU07].
result Recovering MP-system up to a gauge. The study classifies geometrically finite polynomials on the boundary of Blaschke products.
problem Understanding the boundaries of hyperbolic components of Blaschke products.
method Combinatorial classification and construction of self-bumps.
result The closure of the main hyperbolic component is not a topological manifold with boundary for d≥4. The paper proves the existence and uniqueness of certain spacelike hypersurfaces with specific curvature and boundary conditions.
problem Existence and uniqueness of convex, entire, spacelike hypersurfaces with constant σk curvature. method Investigation of hypersurfaces with prescribed set of lightlike directions and perturbation on the ideal boundary at infinity.
result Existence and uniqueness of complete entire spacelike constant σk curvature hypersurfaces with prescribed lightlike directions and perturbation. New methods compare Steklov eigenspaces of free boundary minimal surfaces in balls.
problem Comparing Steklov eigenspaces of free boundary minimal surfaces.
method Developed new methods to compare span of coordinate functions with Steklov eigenspace.
result Proved congruence of free boundary minimal annuli in 3D unit ball.
New examples show manifolds with noncompact boundaries that can't be pseudo-collarable.
problem Identifying manifolds with noncompact boundaries that cannot be pseudo-collarable.
method Provided examples of Z-compactifiable manifolds with noncompact boundaries that fail to be pseudo-collarable. result Found manifolds with noncompact boundaries that cannot be pseudo-collarable.
New findings on lightconvex boundaries in Finslerian spacetimes.
problem Understanding causal structures in Finslerian spacetimes.
method General results for indefinite Finslerian manifolds with boundary, and equivalence among boundary lightconvexity, causally simple interior, and Hausdorff space of cone geodesics.
result Equivalence among boundary lightconvexity, causally simple interior, and Hausdorff space of cone geodesics in globally hyperbolic spacetimes.
Symmetries of Einstein-Weyl manifolds can be extended from boundary surfaces.
problem Extending symmetries from boundary surfaces to Einstein-Weyl manifolds.
method Starting from a symmetry of conformal Cartan connection on a boundary surface, proving symmetries can be extended.
result Symmetries of conformal Cartan connection on the boundary can be extended to symmetries of the Einstein-Weyl manifold.
Connected boundaries of strata of differentials are always connected in various compactifications.
problem Understanding the connectedness of boundaries of differentials' strata in various compactifications.
method Explicit degeneration techniques, algebraic compactifications, and properties of Teichmüller curves.
result The boundaries of differentials' strata are always connected in any complete algebraic compactification.
Adapts viscosity method for free boundary minimal surfaces.
problem Finding min-max free boundary minimal surfaces.
method Adapting Rivière's viscosity method to free boundary conditions.
result Min-max value is sum of branched minimal immersions.
Efficient triangulations help in understanding 3-manifold boundaries.
problem Understanding boundary slopes in 3-manifolds.
method Introducing and studying boundary-efficient triangulations and inflating ideal triangulations.
result There are only finitely many boundary slopes for incompressible and \(\partial\)-incompressible surfaces in compact 3-manifolds.
This paper proves that one-relator groups have a weak Z-structure.
problem The existence of weak Z-structures for all groups of type F.
method Analyzing the geometric properties of one-relator groups and their boundaries.
result Torsion-free one-relator groups have a weak Z-structure.
A Z-structure on a group G was introduced by Bestvina in order to extend the notion of a group boundary beyond the realm of CAT(0) and hyperbolic groups. A refinement of this notion, introduced by Farrell and Lafont, includes a G-equivariance requirement, and is known as an EZ-structure. The…
The odd signature operator is a Dirac operator which acts on the space of differential forms of all degrees and whose square is the usual Laplacian. We extend the result of [15] to prove the gluing formula of the zeta-determinants of Laplacians acting on differential forms of all degrees with respect to the boundary co…
The refined analytic torsion on compact Riemannian manifolds with boundary has been discussed by B. Vertman and the authors, but these two constructions are completely different. Vertman used a double of de Rham complex consisting of the minimal and maximal closed extensions of a flat connection and the authors used we…
Suppose a finitely generated group G is hyperbolic relative to P a set of proper finitely generated subgroups of G. Established results in the literature imply that a "visual" metric on ∂(G,P) is "linearly connected" if and only if the boundary ∂(G,P) has no cut poin…
Symplectic coordinates found on projective structures on orbifolds.
problem Symplectic structure on deformation spaces of convex projective structures.
method Global Darboux coordinates system construction and symplectic space decomposition.
result Symplectic form on deformation space of convex projective structures.
We prove that given a C∞ Riemannian manifold with boundary, any fat triangulation of the boundary can be extended to the whole manifold. We also show that this result holds extends to C1 manifolds, and that in dimensions 2,3 and 4 it also holds for PL manifolds. We employ the main res…
In this paper, we investigate the fixed-point set of an element of a CAT(0) group in its boundary. Suppose that a group G acts geometrically on a CAT(0) space X. Let g∈G and let Fg be the fixed-point set of g in the boundary ∂X. Then we show that Fg=L(Zg), where Zg is …
The paper investigates surfaces with boundary and mean curvature depending on the Gauss map.
problem Investigating surfaces with boundary and mean curvature depending on the Gauss map.
method Investigates H-surfaces in R3 with boundary, proving non-existence and existence of estimates. result Conditions on H ensure compact H-surfaces for certain shapes. New proof for hyperbolic groups using contracting boundaries of cusped spaces.
problem Proving groups are hyperbolic relative to subgroups.
method Proving compact contracting boundary of cusped space implies hyperbolicity.
result If cusped space Gh has compact contracting boundary, then G is hyperbolic relative to subgroups H. Algebras of smooth functions help reconstruct bulk topological types.
problem Reconstructing the smooth topological type of a compact manifold from its boundary.
method Introducing subalgebras of boundary functions and proving their tensor product reconstruction of the bulk algebra.
result The topological algebras A(v) and B(f) allow for the recovery of the smooth topological type of the bulk X. Let (X0,F0) be a compact manifold with boundary endowed with a foliation F0 which is assumed to be measured and transverse to the boundary. We denote by Λ a holonomy invariant transverse measure on (X0,F0) and by R0 the equivalence relation of the foliation. Let…
New index formulae derived for operators on boundary groupoids.
problem Index theory on boundary groupoids of singular spaces.
method Deformation from pair groupoid and explicit construction of index map.
result Explicit index formulae for elliptic operators on boundary groupoids.
Study proves Liouville theorem for specific curvature equations with boundary conditions.
problem Proving Liouville theorem for σk-curvature equations in half spaces with nonlinear boundary conditions. method Established using positive constant curvature equations and variational functional approach.
result Proved Liouville theorem for positive constant σk-curvature equations in R+n and boundary conditions. We prove that if a smoothly bounded strongly pseudoconvex domain D⊂Cn, n≥2, admits at least one Monge-Ampère exhaustion smooth up to the boundary (i.e. a plurisubharmonic exhaustion τ:D→[0,1], which is C∞ at all points except possibly at the unique minimum poi…
Let X be a compact smooth manifold with boundary. In this article, we study the spaces V†(X) and V‡(X) of so called boundary generic and traversally generic vector fields on X and the place they occupy in the space V(X) of all fields (see Theorems \ref{th3.4} and Theo…
In this paper, we study the Dirichlet problem of the geodesic equation in the space of Kähler cone metrics $\mathcal H_\b$; that is equivalent to a homogeneous complex Monge-Ampère equation whose boundary values consist of Kähler metrics with cone singularities. Our approach concerns the generalization of the space def…
In this paper we discuss the refined analytic torsion on an odd dimensional compact oriented Riemannian manifold with boundary under some assumption. For this purpose we introduce two boundary conditions which are complementary to each other and well-posed for the odd signature operator B in the sense of Se…
We show that if L is a codimension-one lamination in a finite volume hyperbolic 3-manifold such that the principal curvatures of each leaf of L are all in the interval (−δ,δ) for a fixed δ∈[0,1) and no complimentary region of L is an interval bundle over a surface, then each bo…
Given an n-gon, the poset of all collections of pairwise non-crossing diagonals is isomorphic to the face poset of some convex polytope called \textit{associahedron}. We replace in this setting the n-gon (viewed as a disc with n marked points on the boundary) with an arbitrary oriented surface with a number of la…
We show that the complex hyperbolic metrics defined by Deligne-Mostow and Thurston on M0,n are singular Kähler-Einstein metrics when M0,n is embedded in the Deligne-Mumford-Knudsen compactification M0,n. As a consequence, we obtain a formula computing the volu…
Contractible diffeomorphism groups on lens spaces derived from Morse-Bott foliations.
problem Understanding the structure of diffeomorphism groups on lens spaces.
method Analyzing Morse-Bott foliations and their diffeomorphisms.
result Contractible diffeomorphism groups on lens spaces.
Let μ be a probability measure on Out(FN) with finite first logarithmic moment with respect to the word metric, finite entropy, and whose support generates a nonelementary subgroup of Out(FN). We show that almost every sample path of the random walk on (Out(FN),μ), when realized in Culle…
Stokes' theorem's boundary maximizes entropy.
problem Characterizing the boundary of a manifold using entropy.
method Maximizing entropy for codimension-1 submanifolds satisfying Stokes' theorem.
result The boundary of a manifold maximizes the entropy functional.
Lower bounds for PL 4-manifolds with boundary are improved.
problem Estimating PL 4-manifolds with boundary.
method Proved inequalities for regular genus and gem-complexity.
result Improved lower bounds for PL 4-manifolds with boundary.
The paper studies diffeomorphisms of a specific foliation on a Klein bottle.
problem Computing homotopy types of diffeomorphism groups for a specific foliation.
method Analyzes a Morse-Bott foliation on a solid Klein bottle and its twisted bundle.
result Computes homotopy types of foliated and leaf-preserving diffeomorphism groups.