arXiv research

New interpretation of discrete conformality using polyhedral convex hulls.

Study convex hulls of orbits for compact groups, defining new invariants related to polynomial degrees.

A famous construction of Gelfand, Kapranov and Zelevinsky associates to each finite point configuration $A \subset \mathbb{R}^d$ a polyhedral fan, which stratifies the space of weight vectors by the combinatorial types of regular subdivisions of $A$. That fan arises as the normal fan of a convex polytope. In a complete…

The Delaunay tessellation of a locally finite subset of hyperbolic space is constructed using convex hulls in Euclidean space of one higher dimension. For finite and lattice-invariant sets it is proven to be a polyhedral decomposition, and versions (necessarily modified from the Euclidean setting) of the empty circumsp…

We prove that the Koebe circle domain conjecture is equivalent to the Weyl type problem that every complete hyperbolic surface of genus zero is isometric to the boundary of the hyperbolic convex hull of the complement of a circle domain. It provides a new way to approach the Koebe's conjecture using convex geometry. Co…

Study on volumes of random inscribed polytopes in projective geometries.

The paper characterizes sets with infinite hyperbolic convex hull volume.

Study shows non-compact convex hulls in certain metric spaces.

Deep learning models generalize by extending decision boundaries outside the convex hull of training data.

The paper transforms a convex hull into a concave surface around a point cloud.

New proofs given for space curves with totally positive torsion.

Estimates convex hulls of smooth function images with error bounds.

For a convex curve in an even-dimensional affine space we introduce a series of convex domains (called Young hulls), describe their structure and give a formulas fo the volume of the biggest of these domains. This paper is an attempt to generalize the classical isoperimetric inequality for the volume of the convex hull…

We obtain an upper bound for the volume of the convex hull of a simple closed Frenet curve with exactly four vertices, i.e., four points of vanishing torsion, and lying on the boundary of its convex hull. Moreover, we show that the upper bound is attained when the curve intersects every plane in at most four points, a …

Study finds knots with ideal length need not have smallest volume.

Study on polyhedra rigidity, finding non-existence of flexible weakly convex decomposable polyhedra.

Optimal algorithm finds if point is in convex hull of distributions.

Optimum in Convex Hulls (OCH) generalizes clinical trial results to broader populations.

We establish a close connection between stable commutator length in free groups and the geometry of sails (roughly, the boundary of the convex hull of the set of integer lattice points) in integral polyhedral cones. This connection allows us to show that the scl norm is piecewise rational linear in free products of Abe…

Estimate collapsibility of causal effects in CPDAGs via strong d-convex hulls.

We prove that a 3-dimensional hyperbolic cusp with convex polyhedral boundary is uniquely determined by the metric induced on its boundary. Furthemore, any hyperbolic metric on the torus with cone singularities of positive curvature can be realized as the induced metric on the boundary of a convex polyhedral cusp. The …

Flat metrics on hyperbolic surfaces embed as polyhedral surfaces in (2+1)-spacetimes.

Study convex hyperbolic cone-metrics on 3-manifold boundaries, proving unique bent realizations.

Sketching algorithm finds closest point on convex hull efficiently.

Study on curvature bounds for specific hypersurfaces in Anti-de Sitter space.

The main result is a direct proof of the implication $(LVKF_{k,3})\Rightarrow( LT_{3k-1,3})$ below. Consider the following statements: ($LVKF_{1,3}$) From any 11 points in $\mathbb{R}^{3}$ one can choose 3 pairwise disjoint triples whose convex hulls have a common point. ($LVKF_{k,3}$) From any $6k + 5$ points in $ \m…

Soap films collapse only if their bulk has negative pressure, forming convex shapes.

New approach to convex hulls for low-rank problems.

The paper develops mixed-integer formulations for neural networks using partitioning.

A curve of minimum length to enclose a unit sphere in 3D is at least 4π.

Polyhedral surfaces can be broken down into parallelograms.

We show that for any extreme curve in a 3-manifold M, there exist a canonical mean convex hull containing all least area disks spanning the curve. Similar result is true for asymptotic case in hyperbolic 3-space such that for any asymptotic curve, there is a canonical mean convex hull containing all minimal planes span…

We show how to construct the nonstandard hull of certain infinite-dimensional Lie algebras in order to generalize a theorem of Pestov on the enlargeability of Banach-Lie algebras. In the process, we consider a nonstandard smoothness condition on functions between locally convex spaces to ensure that the induced functio…

Locally finite complexes with polyhedral $CAT(0)$ metrics are arborescent.

Dual explanation method using convex hulls and example-based vectors.

Characterizes billiard and quasigeodesic flows in polyhedral convex bodies.

GraphHull models networks with clear multi-scale explanations of community structure.

The integer hull of a polyhedron is the convex hull of the integer points contained in it. We show that the vertices of the integer hulls of a rational family of polyhedra of size O(n) have quasipolynomial coordinates. As a corollary, we show that the stable commutator length of elements in a surgery family is a ratio …

We define two non-linear operations with random (not necessarily closed) sets in Banach space: the conditional core and the conditional convex hull. While the first is sublinear, the second one is superlinear (in the reverse set inclusion ordering). Furthermore, we introduce the generalised conditional expectation of r…

The convex hull of a set K in space consists of points which are, in a certain sense, "surrounded" by K. When K is a closed curve, we define its higher hulls, consisting of points which are "multiply surrounded" by the curve. Our main theorem shows that if a curve is knotted then it has a nonempty second hull. This pro…

Paper develops compact formulations for optimization problems with rank-one convex functions and indicator variables.

Traditional nearest points methods use all the samples in an image set to construct a single convex or affine hull model for classification. However, strong artificial features and noisy data may be generated from combinations of training samples when significant intra-class variations and/or noise occur in the image s…

Novel technique reduces Bayesian network complexity while preserving inference accuracy.

New conditions ensure Dantzig-Wolfe relaxation matches rank-constrained optimization problems.

We formalize and study the natural approach of designing convex surrogate loss functions via embeddings, for problems such as classification, ranking, or structured prediction. In this approach, one embeds each of the finitely many predictions (e.g.\ rankings) as a point in $\mathbb{R}^d$, assigns the original loss val…

We prove that if an analytic subset $A$ of a linear metric space $X$ is not contained in a $σZ_ω$-subset of $X$ then for every Polish convex set $K$ with dense affine hull in $X$ the sum $A+K$ is non-meager in $X$ and the sets $A+A+K$ and $A-A+K$ have non-empty interior in the completion $\bar X$ of $X$. This implies t…

The paper studies the convex hull of random points in a triangle, focusing on the asymptotic behavior and phase transitions.

We give upper bounds on the principal curvatures of a maximal surface of nonpositive curvature in three-dimensional Anti-de Sitter space, which only depend on the width of the convex hull of the surface. Moreover, given a quasisymmetric homeomorphism $φ$, we study the relation between the width of the convex hull of th…