Mathematics Problem Archive
1.3 (Cooper) — Convexity of projective structures on hyperbolic 3-manifolds
v1.3 research notesIf $M$ is a closed hyperbolic $3$-manifold, is every projective structure on $M$ convex?...
1.4 (Danciger) — Convex projective structures on glued figure-eight complements
v1.3 research notesLet $N$ be the closed $3$-manifold obtained by gluing two copies of the figure-eight knot complement along their torus boundaries by a homeomorphism. ...
1.5 (Danciger) — Convex projective structures and hyperbolic JSJ pieces
v1.3 research notesLet $N$ be a closed $3$-manifold whose JSJ decomposition contains only hyperbolic pieces. Does $N$ admit a convex projective structure?...
2.1 (Leitner) — Limits between Thurston geometries
v1.3 research notesGeometric transitions are continuous paths of geometries that abruptly change type in the limit. Understand all transitions between the eight Thurston...
2.2 (Cooper) — An invariant polynomial on a tensor product
v1.3 research notesDoes there exist a nonzero polynomial on $U\otimes V\otimes W$ invariant under $SL(U)\times SL(V)\times SL(W)$ when $\dim U=\dim V=4$ and $\dim W=8$?...
2.3 (Cooper) — Hausdorff limits of conjugates of an isometry group
v1.3 research notesLet $\beta$ be a nondegenerate bilinear form on a finite-dimensional real vector space $V$, and let $G=\operatorname{Isom}(\beta)\subset GL(V)$. Which...
3.2 (Agol) — A minimal-Thurston-norm surface from a tree action
v1.3 research notesLet $M$ be a $3$-manifold whose fundamental group acts on a simplicial tree without global fixed points. In the covering space associated to an edge s...
3.3 (Agol) — Injective surfaces with only double curves
v1.3 research notesDoes every closed hyperbolic $3$-manifold contain a closed $\pi_1$-injective surface with only double curves of intersection?...
3.4 (Agol) — Injective surfaces with the 1-line property
v1.3 research notesDoes every closed hyperbolic $3$-manifold contain a closed $\pi_1$-injective surface with the 1-line property: in the universal cover, every pair of p...
3.5 (Agol) — Quasi-Fuchsian surfaces cubulating away from cusps
v1.3 research notesDo cusped finite-volume hyperbolic $3$-manifolds have closed quasi-Fuchsian surfaces that cubulate except for the cusps? Equivalently in the stated ge...
3.6 (Agol) — Virtual semi-fibering
v1.3 research notesAre finite-volume hyperbolic $3$-manifolds virtually semi-fibered?...
3.7 (Agol) — Kleinian groups with closed quasi-Fuchsian surface subgroups
v1.3 research notesWhich Kleinian groups admit closed quasi-Fuchsian surface subgroups?...
3.8 (Agol) — Twisted homology products after cutting along a surface
v1.3 research notesLet $M$ be a $3$-manifold, let $\phi:\pi_1M\to\mathbb{Z}$ be dual to $(\Sigma,\partial\Sigma)\subset(M,\partial M)$, and let $N$ be obtained by cuttin...
3.10 (Futer, Schleimer) — A practical 3-manifold homeomorphism algorithm
v1.3 research notesIs there a practical algorithm to test whether a pair of $3$-manifolds are homeomorphic?...
3.11 (Walsh) — Unbounded CAT(0) cubical dimension
v1.3 research notesThe CAT(0) cubical dimension of a group $G$ is the least dimension of a CAT(0) cubical space on which $G$ acts geometrically. Is there a sequence of c...
4.1 (Agol) — Virtual embeddings in hyperbolic reflection groups
v1.3 research notesDo closed hyperbolic $3$-manifold groups have finite-index subgroups that embed in a word-hyperbolic reflection group?...
4.2 (Futer) — The surface subgroup conjecture for cubulated hyperbolic groups
v1.3 research notesDoes every freely indecomposable cubulated hyperbolic group contain the fundamental group of a closed hyperbolic surface?...
4.3 (Cooper) — 3-manifold groups acting on the affine building for $SL(4,\mathbb{R})$
v1.3 research notesIf $M$ is a closed $3$-manifold, when does $\pi_1M$ act on the affine building for $SL(4,\mathbb{R})$ so that the quotient retracts to $M$?...
4.4 (Kassel, Mann) — Proper affine actions on $\mathbb{R}^5$
v1.3 research notesLet $\Gamma$ be a discrete group acting properly discontinuously by affine transformations on $\mathbb{R}^5$. Is $\Gamma$ virtually an extension of a ...
4.5 (Kassel, Mann) — Proper affine surface-group actions on $\mathbb{R}^6$
v1.3 research notesClassify all properly discontinuous affine actions of a given closed surface group on $\mathbb{R}^6$....
4.6 (Kassel, Mann) — Minimal dimension of a proper affine Coxeter-group action
v1.3 research notesFor a given right-angled Coxeter group, what is the least $n$ for which it admits a proper affine action on $\mathbb{R}^n$?...
5.1 (Agol) — Hyperbolic 3-manifolds with infinitely generated fundamental group
v1.3 research notesCharacterize hyperbolic $3$-manifolds with infinitely generated fundamental group. In particular, is there a $3$-manifold that is locally hyperbolic, ...
5.2 (Agol) — Large injectivity radius in hyperbolic homology manifolds
v1.3 research notesDo there exist fibered hyperbolic $3$-manifolds that are homology $S^2\times S^1$ and have arbitrarily large injectivity radius? Are there hyperbolic ...
5.3 (Agol) — Thurston norm polytopes
v1.3 research notesCharacterize the Thurston norm polytopes of finite-volume hyperbolic $3$-manifolds....
5.4 (Agol) — Virtual CAT(0) cubical manifold models
v1.3 research notesDoes every hyperbolic $3$-manifold have a finite-sheeted cover homeomorphic to a CAT(0) cube complex?...
5.5 (Agol) — Asymptotic frequency of small drilled manifolds
v1.3 research notesFix $\mu$ below the three-dimensional Margulis constant. For hyperbolic $3$-manifolds of volume less than $V$, drill all closed geodesics of length le...
5.6 (Agol) — Cusp-preserving virtual domination
v1.3 research notesIf $M_1$ and $M_2$ are cusped hyperbolic $3$-manifolds, does there exist a cover $M'_1\to M_1$ and a nonzero-degree map $M'_1\to M_2$ taking cusps to ...
5.7 (Agol) — Renormalized volume as a metric
v1.3 research notesThe renormalized volume of quasi-Fuchsian groups gives a function $\rho:\mathcal{T}(S)\times\mathcal{T}(S)\to\mathbb{R}$. Is $\rho$ a metric on the Te...
5.8 (Schleimer) — Why SnapPy works in practice
v1.3 research notesGive a rigorous explanation for why SnapPy works so well in practice....
5.9 (Cooper) — Thurston's Lego sets in dimensions at least four
v1.3 research notesGiven $R>0$ and an integer $n\geq4$, is there an $\varepsilon>0$ and a finite set of hyperbolic $n$-simplices such that every closed cone $n$-manifold...
5.11 (Futer) — A combinatorial model with explicit bilipschitz constants
v1.3 research notesBuild a combinatorial model for hyperbolic $3$-manifolds with explicit bilipschitz constants....
5.12 (Reid) — Finite quotients of finite-covolume Kleinian groups
v1.3 research notesLet $\Gamma$ be a Kleinian group of finite covolume, and let $\mathcal{C}(\Gamma)$ be the set of isomorphism classes of its finite quotient groups. Do...
5.13 (Reid) — Finite quotients of free groups
v1.3 research notesFor $\Gamma=F_r$ with $r\geq2$, does $\mathcal{C}(F_r)$ determine $F_r$ up to isomorphism?...
5.14 (Reid) — Finite-quotient rigidity among 3-manifold groups
v1.3 research notesLet $\Gamma$ be a Kleinian group of finite covolume. Does its set $\mathcal{C}(\Gamma)$ of finite quotient isomorphism classes determine $\Gamma$ amon...
5.15 (Gabai, Trnkova) — Ideal triangulations with arbitrarily many positive tetrahedra
v1.3 research notesLet $M$ be a hyperbolic $3$-manifold and let $n$ be any positive integer. Does $M$ admit an ideal triangulation with $m\geq n$ positively oriented tet...
5.16 (Walsh) — Hyperbolic groups with Kleinian-type boundaries
v1.3 research notesIf $G$ is a Gromov-hyperbolic group whose boundary is homeomorphic to the limit set of a convex-cocompact Kleinian group, is $G$ virtually a convex-co...
5.17 (Walsh) — Limit sets of convex-cocompact Kleinian groups
v1.3 research notesWhich subsets of $S^2$ can occur as limit sets of convex-cocompact Kleinian groups?...
5.18 (Walsh) — Sierpiński carpets and continua in Kleinian limit sets
v1.3 research notesFor which Kleinian groups does the limit set contain a Sierpiński carpet? For which Kleinian groups does the limit set contain a continuum?...
5.19 (Walsh) — Limit sets of graph Kleinian groups
v1.3 research notesCharacterize the limit sets of graph Kleinian groups and iterated graph-Kleinian groups. A graph Kleinian group is a convex-cocompact Kleinian group f...
6.1 (I. Kapovitch) — Random walks and generic pseudo-Anosov singularities
v1.3 research notesShow that a random walk on the mapping class group gives a pseudo-Anosov element whose invariant foliations have generic trivalent singularities with ...
6.2 (Maher) — Random tetrahedron-gluing pseudomanifolds
v1.3 research notesStart with $n$ tetrahedra and glue their faces together at random. The vertex links need not be spheres but are essentially random triangulated surfac...
6.3 (Maher) — Structure behind Rivin's experimental regularity
v1.3 research notesRivin's experimental results appear extremely regular, possibly indicating additional structure. Investigate this phenomenon....
6.4 (Maher) — Generic mapping-class orbit points in Teichmüller balls
v1.3 research notesFor the orbit of a point $x$ in Teichmüller space under the mapping class group, show that as $r\to\infty$: (1) the proportion of orbit points in the ...
7.1 (Long) — Principal and Euclidean rings of integers from totally real polynomials
v1.3 research notesLet $f(x)\in\mathbb{Z}[x]$ be irreducible over $\mathbb{Q}$ with all roots real, let $f(\alpha)=0$, let $k=\mathbb{Q}(\alpha)$, and let $\mathcal{O}_k...
7.2 (Long) — Clique numbers in unit- and prime-difference graphs
v1.3 research notesFor $\mathcal{O}_k$ as in item 7.1, let $\Gamma_{\mathrm{unit}}$ have vertex set $\mathcal{O}_k$, joining two elements when their difference is a unit...
7.3 (Manning) — Number fields as trace fields
v1.3 research notesIf $k$ is a number field that is not totally real, is there a hyperbolic $3$-manifold with trace field $k$?...
7.6 (McMullen) — Totally geodesic surfaces and arithmeticity
v1.3 research notesLet $M$ be a finite-volume hyperbolic $3$-manifold. If $M$ contains infinitely many immersed totally geodesic surfaces, must $M$ be arithmetic?...
8.1 (Agol) — Strongly irreducible Heegaard splittings of Haken manifolds
v1.3 research notesDo Haken hyperbolic $3$-manifolds have strongly irreducible Heegaard splittings?...
8.2 (Dunfield) — Profinite detection of knot complements
v1.3 research notesFor a hyperbolic $3$-manifold with torus boundary, does its profinite completion determine whether it is a knot complement?...
8.4 (Schleimer) — Detecting reducible Heegaard splittings
v1.3 research notesIs there an algorithm to detect whether a Heegaard splitting is reducible and, if so, find a reducing curve?...