Existence of Equal-Volume Least-Area Partitions
v1.3 research notesDo least-area partitions of $\mathbb{R}^n$ into regions of unit volume exist? Give the correct definition and determine their regularity....
Optimality and Existence of the Weaire-Phelan Foam
v1.3 research notesIs the Weaire--Phelan A15 foam the optimal partition of three-space into equal volumes, and can the existence of a foam in the A15 pattern be proved?...
Restricted Optimality of Kelvin's Foam
v1.3 research notesProve or disprove successively that the Kelvin cell is the least-area fundamental domain for the BCC torus, that it minimizes among all unit-volume fl...
Maximum Shear Modulus of Planar Froths
v1.3 research notesProve or disprove that no two-dimensional froth of average bubble area one has shear modulus in any direction exceeding that of the regular hexagonal ...
Sharp Isoperimetric Constant for Bubble Clusters
v1.3 research notesFind the best constant $C$ in the inequality $A\leq C(\int_B H+L)^2$ for a bubble cluster of area $A$, mean curvature $H$, and boundary length $L$. De...
Gromov-Knothe Isoperimetry for Multiple Regions
v1.3 research notesExtend Gromov's Knothe-based proof of the isoperimetric inequality to multiple regions, and determine whether its vector field can be chosen canonical...
Melzak's Shortest-Edge Polyhedron Conjecture
v1.3 research notesProve that the unit-volume polyhedron with shortest total edge length is an equilateral triangular prism, and establish existence of a minimizer....
Least Soap Films on Tetrahedral and Open-Book Frames
v1.3 research notesIs the cone over the regular tetrahedron the smallest soap film having the entire tetrahedral frame as boundary? For a frame of two rectangles sharing...
Soap Film on a Regular Octahedral Frame
v1.3 research notesFor a regular octahedral wire frame, determine the least-area soap film separating the eight regions, both with ordinary and fractional-density soap f...
CMC Graphs Spanning Convex Planar Curves
v1.3 research notesIf a convex planar curve $\Gamma$ has length less than $2\pi$, does it bound a graph of constant mean curvature one? Determine the volume threshold $V...
CMC Surfaces with Circular Boundary
v1.3 research notesIs every embedded constant-mean-curvature surface, or every immersed constant-mean-curvature disk, with boundary a round circle necessarily a spherica...
Sharp Interior Curvature Bound for Minimizing Hypersurfaces
v1.3 research notesFind the best constant $C$ such that the principal curvatures of an area-minimizing hypersurface in low dimensions are bounded by $C/r$ at a point who...
Realizing Statistical Manifolds in Dually Flat Manifolds
v1.3 research notesFor a statistical manifold $(M,g,\nabla,\nabla^*)$, find conditions under which it can be realized as an $n$-dimensional submanifold of an $m$-dimensi...
Probability Densities and Equiaffine Transformations
v1.3 research notesThe smooth positive probability densities on $S^1$ are diffeomorphic to the manifold of smooth equiaffine transformations of $S^1$. Find the correspon...
Dually Flat Structures on Riemannian Manifolds
v1.3 research notesGiven a Riemannian manifold $(M,g)$, can one always introduce a symmetric $(0,3)$-tensor $T$ so that $(M,g,\nabla,\nabla^*)$ is dually flat? If the co...
Statistical Manifolds from Probability Families
v1.3 research notesGiven a statistical manifold, determine conditions for the existence of a family of probability distributions whose induced statistical manifold coinc...
Fundamental Groups of Compact Affine Flat Manifolds
v1.3 research notesDetermine the fundamental group of a compact affine flat manifold....
Isothermal Coordinates for Affine Minimal Surfaces
v1.3 research notesDo affine minimal surfaces admit isothermal coordinates with respect to their affine fundamental form, analogously to minimal surfaces in Euclidean th...
Curvature-Type Tensors of Statistical Manifolds
v1.3 research notesLet $K(X,Y,Z,W)=h(R(X,Y)Z,W)$ be the curvature $(0,4)$-tensor of a statistical manifold. Investigate the structure of all $(0,4)$-tensors satisfying $...
Integrable Radial Distributions and One-Conformal Flatness
v1.3 research notesOn a statistical manifold, let $D$ be the rank-$(n-1)$ distribution orthogonal to the velocity of the $\nabla$-geodesic from a fixed point. If every s...
Inflection Points of Projectively Flat Curves
v1.3 research notesEstimate the minimum number of inflection points of a closed curve on a Riemann surface with a projectively flat connection....
Affine Vertices and Inflection Points
v1.3 research notesFor a closed curve on a Riemann surface with projectively flat connection, estimate the number of affine vertices and, assuming isolated inflection po...
Global Affine Curve Flow
v1.3 research notesProve existence of a time-global solution to the affine-plane curve evolution equation $\partial x/\partial u=(1+kp)x''$, where $u$ is time, $x''$ is ...
Stein Tangent Bundles of Complete Hessian Manifolds
v1.3 research notesIf $(M,g)$ is a complete Hessian manifold, is its tangent bundle with the natural complex structure a Stein manifold? In particular, if a convex domai...
Stability of Hessian Metrics
v1.3 research notesLet $M$ be a compact Hessian manifold and deform its affine structure. Does every sufficiently small deformation admit a Hessian metric?...
Nonproduct Compact Hessian Manifolds
v1.3 research notesConstruct compact Hessian manifolds other than direct products of hyperbolic and flat compact Hessian manifolds; in particular, construct one with no ...
Boundaries of Groups and Kleinian Groups — Problem 1
v1.3 research notesWhat spaces can arise as boundaries of hyperbolic groups? As a sub-problem: For which k do k-dimensional stable Menger spaces appear as boundaries?...
Boundaries of Groups and Kleinian Groups — Problem 3
v1.3 research notesWhat 2-dimensional spaces arise as boundaries of hyperbolic groups?...
Boundaries of Groups and Kleinian Groups — Problem 13
v1.3 research notesFind further universality phenomena: classes of groups or spaces of different nature whose ideal boundaries are nevertheless all homeomorphic, beyond ...
Boundaries of Groups and Kleinian Groups — Problem 28
v1.3 research notesExtend the known necessary conditions for a compact metrizable space $X$ to be the boundary of a proper cocompact CAT(0) space, or give a complete cla...
Boundaries of Groups and Kleinian Groups — Problem 29
v1.3 research notesDoes every CAT(0) group have finite asymptotic dimension?...
Boundaries of Groups and Kleinian Groups — Problem 40
v1.3 research notesDevelop a theory for analysis on the ideal boundaries of relatively hyperbolic groups, as it is done for hyperbolic groups....
Boundaries of Groups and Kleinian Groups — Problem 41
v1.3 research notesIn what generality does quasiconformal imply quasisymmetric?...
Boundaries of Groups and Kleinian Groups — Problem 51
v1.3 research notesAre all quasi-isometric embeddings between higher-rank symmetric spaces either isometries or algebraic in this way?...
Boundaries of Groups and Kleinian Groups — Problem 64
v1.3 research notes[Cannon–Thurston] Is this action conjugate to a conformal action?...
Boundaries of Groups and Kleinian Groups — Problem 67
v1.3 research notesLet H ⊂ G be a hyperbolic subgroup of a hyperbolic group (we do not assume that H is quasiconvex). Is it true that there exists an equivariant continu...
Boundaries of Groups and Kleinian Groups — Problem 68
v1.3 research notesWhat is the Poisson boundary of the free group with an arbitrary measure?...
Boundaries of Groups and Kleinian Groups — Problem 72
v1.3 research notesCharacterize the hitting measure ν on PMF obtained from the random walk by mapping classes on Teichm¨ uller space. Is it absolutely continuous with re...
Boundaries of Groups and Kleinian Groups — Problem 73
v1.3 research notesWhat is the Poisson boundary of Outer space?...
Boundaries of Groups and Kleinian Groups — Problem 74
v1.3 research notesIs there are meaningful structure theory for lacunary hyperbolic groups? Can one define a useful boundary for such groups? Is it true that either Out(G...
Boundaries of Groups and Kleinian Groups — Problem 75
v1.3 research notesEvery relatively hyperbolic group has cut points in all of its asymptotic cones. To what extent does the converse hold? Characterize the finitely gene...
Boundaries of Groups and Kleinian Groups — Problem 77
v1.3 research notesFor the fundamental group G of a closed hyperbolic n-manifold consider a short exact sequence 1 →Zp → Γ → G → 1. Is the group Γ residually finite? In o...
Boundaries of Groups and Kleinian Groups — Problem 79
v1.3 research notesLet G be a Gromov-hyperbolic Coxeter group. Does G admit a discrete embedding in Isom(Hn) for large n?...
Boundaries of Groups and Kleinian Groups — Problem 81
v1.3 research notesLet G ⊂ Isom(Hn) be a discrete torsion-free finitelygenerated subgroup without abelian subgroups of rank ≥ 2. Is it true that (a) cdZ(G) ≤ Hdim(Λc(G)) ...
Boundaries of Groups and Kleinian Groups — Problem 90
v1.3 research notesGeneralize Bestvina-Feighn combination theorem from graphs of groups to complexes of groups....
Boundaries of Groups and Kleinian Groups — Problem 92
v1.3 research notesThere is a theory of quasi-convex groups acting on Gromov hyperbolic spaces, generalizing the theory of convex-compact groups of isometries of the rea...
Boundaries of Groups and Kleinian Groups — Problem 93
v1.3 research notesExtend this relation of Anosov structure and dynamics on the limit set to representations of other hyperbolic groups....
Boundaries of Groups and Kleinian Groups — Problem 95
v1.3 research notesObtain new rigidity results for embeddings of realhyperbolic lattices into higher-rank semisimple Lie groups in terms of the boundary maps....
Boundaries of Groups and Kleinian Groups — Problem 99
v1.3 research notesConsider Teichm¨ uller spaceT (S) with Teichm¨ uller metric. Does it have quadratic isoperimetric inequality?...
Boundaries of Groups and Kleinian Groups — Problem 105
v1.3 research notesCompute cogrowth for notable subgroups $H\subset G$, where cogrowth is the growth of the Schreier graph $\Gamma_{G/H}$. In particular: prove that the ...