Mathematics Problem Archive
Boundary theorems for geometric coding trees
v1.3 research notesWhich theorems about boundary behavior of Riemann maps have analogues for geometric coding trees?...
Representative transcendental entire dynamics
v1.3 research notesFind a collection of representative examples of transcendental entire maps whose dynamics may serve as models for general phenomena....
Newton dynamics for entire functions
v1.3 research notesDescribe the dynamics of Newton's method when applied to broad natural classes of transcendental entire functions....
An orbit converging to an irrationally indifferent fixed point
v1.3 research notesUnder the hypotheses of Eremenko–Lyubich Question 2, can even a single orbit converge to $z_0$?...
Degenerate-flow limits of bad Newton polynomials
v1.3 research notesCall a polynomial bad if its Newton map has an attracting cycle that is not a root. Prove that every bad degree-$d$ polynomial $f_1$ belongs to a one-...
Local connectivity of quadratic Julia sets
v1.3 research notesFor $P_c(z)=z^2+c$ with connected Julia set, characterize the parameters $c$ for which $J(P_c)$ is locally connected....
Lift-family criterion for finite kneading data
v1.3 research notesFind a general property of a lifting family that guarantees convergence of the real Thurston algorithm for every periodic or preperiodic kneading sequ...
Lift-family criterion for arbitrary kneading data
v1.3 research notesFind a general property of a lifting family that guarantees convergence of the real Thurston algorithm for arbitrary kneading sequences....
Boundary fixed points in rank-zero Hénon components
v1.3 research notesIn the rank-zero case, if the limiting map on an invariant stable component is constant with value $x_0\in\partial U$, prove that one eigenvalue at $x...
Herman-ring retracts for Hénon maps
v1.3 research notesCan the subsequential limit map on an invariant stable component of a polynomial diffeomorphism of $\mathbb C^2$ be a retraction onto a Herman ring or...
Products involving Herman rings as stable components
v1.3 research notesIn the rank-two case for a polynomial diffeomorphism of $\mathbb C^2$, can an invariant stable component be a product of two Herman rings, or a produc...
Density of hyperbolic rational maps
v1.3 research notesFor every degree $d$, prove that expanding (hyperbolic, Axiom A) maps are dense in the spaces $\operatorname{Rat}_d$ of rational maps and $\operatorna...
Haken-type decomposition for rational maps
v1.3 research notesDevelop an analogue of the Haken decomposition for geometrically finite rational maps. In particular, if the Julia set is disconnected, can the map be...
Voronoi Diagram of Lines in 3D
v1.3 research notesWhat is the combinatorial complexity of the Voronoi diagram of a set of lines (or line segments) in three dimensions?...
Union of Fat Objects in 3D
v1.3 research notesWhat is the complexity of the union of ``fat'' objects in $\mathbb{R}^3$?...
$k$-sets
v1.3 research notesWhat is the maximum number of $k$-sets? (Equivalently, what is the maximum complexity of a $k$-level in an arrangement of hyperplanes?)...
Simple Linear-Time Polygon Triangulation
v1.3 research notesIs there a deterministic, linear-time polygon triangulation algorithm significantly simpler than that of Chazelle?...
Point Location in 3D Subdivision
v1.3 research notesIs there an $O(n)$-space data structure that supports $O(\log n)$-time point-location queries in a three-dimensional subdivision of $n$ faces?...
Simple Polygonalizations
v1.3 research notesCan the number of simple polygonalizations of a set of $n$ points in the plane be computed in polynomial time? A simple polygonalization is a simple p...
Visibility Graph Recognition
v1.3 research notesGiven a visibility graph $G$ and a Hamiltonian circuit $C$, determine in polynomial time whether there is a simple polygon whose vertex visibility gra...
Vertical Decompositions in $\mathbb{R}^d$
v1.3 research notesWhat is the complexity of the vertical decomposition of $n$ surfaces in $\mathbb{R}^d$, $d \ge 5$?...
Minimum-Link Path in 2D
v1.3 research notesCan a minimum-link path among polygonal obstacles be found in subquadratic time?...
Polygonal Curve Simplification
v1.3 research notesCan an $n$-vertex polygonal curve be simplified in time nearly linear in $n$?...
Polyhedral Surface Approximation
v1.3 research notesHow efficiently can one compute a polyhedral surface that is an $\epsilon$-approximation of a given triangulated surface in $\mathbb{R}^3$?...
Flip Graph Connectivity in 3D
v1.3 research notesIs the flip graph connected for general-position points in $\mathbb{R}^3$? Given a set of $n$ points in $\mathbb{R}^3$, the flip graph has a node for ...
Hamiltonian Tetrahedralizations
v1.3 research notesCan every convex polytope in $\mathbb{R}^3$ be partitioned into tetrahedra such that the dual graph has a Hamiltonian path?...
Trapping Light Rays with Segment Mirrors
v1.3 research notesIs it possible to trap all the light from one point source by a finite collection of two-sided disjoint segment mirrors? A light ray is trapped if it ...
Extending Pseudosegment Arrangements by Subdivision
v1.3 research notesHow many intersections among an arrangement of pseudosegments in the plane must be added as vertices to allow the pseudosegment arrangment to be exten...
Counting Polyominoes
v1.3 research notesHow many polyominoes on $n$ squares are there? A polyomino is a connected interior-disjoint union of axis-aligned unit squares joined edge-to-edge, in...
Compatible Triangulations
v1.3 research notesIs it true that every two sets of $n$ planar points in general position with the same number points on their convex hulls have compatible triangulatio...
The Number of Pointed Pseudotriangulations
v1.3 research notesFor a planar point set $S$, is the number of pointed pseudotriangulations always at least the number of triangulations? A pseudotriangle is a planar p...
Sorting $X+Y$ (Pairwise Sums)
v1.3 research notesGiven two sets of numbers, each of size $n$, how quickly can the set of all pairwise sums be sorted? In symbols, given two sets $X$ and $Y$, our goal ...
Vertex-Unfolding Polyhedra
v1.3 research notesConsider a polyhedron with simply connected facets (no holes on a facet) and without boundary (every edge is incident to exactly two facets). Can the ...
General Unfoldings of Nonconvex Polyhedra
v1.3 research notesCan every closed polyhedron be cut along its surface and unfolded into one piece in the plane without overlap? Such an unfolding is called a general u...
3D Minimum-Bend Orthogonal Graph Drawings
v1.3 research notesDoes every simple graph with maximum vertex degree $\Delta \leq 6$ have a 3D orthogonal point-drawing with no more than two bends per edge? A 3D ortho...
Planar Euclidean Maximum TSP
v1.3 research notesWhat is the complexity of finding a tour of maximum Euclidean length for a planar point set?...
Traveling Salesman Problem in Solid Grid Graphs
v1.3 research notesWhat is the complexity of finding a shortest tour in a solid planar grid graph? A planar grid graph is a graph whose vertices are any set of points on...
Pallet Loading
v1.3 research notesWhat is the complexity of the pallet loading problem? Given two pairs of numbers, $(A,B)$ and $(a,b)$, and a number $n$, decide whether $n$ small rect...
Most Circular Partition of a Square
v1.3 research notesWhat is the optimal partition of a square into convex pieces such that the circularity of the pieces is optimized? The circularity of a polygon is the...
Transforming Polygons via Vertex-Centroid Moves
v1.3 research notesGiven an arbitrary polygon, transform it by a finite sequence of ``vertex-centroid'' moves to a regular polygon. A vertex-centroid move is a translati...
Lines Tangent to Four Unit Balls
v1.3 research notesGiven a set of $n$ unit-radius balls in $\mathbb{R}^3$, what is the number of lines that are tangent to four of the balls in the set, and miss all the...
Volume Maximizing Convex Shape
v1.3 research notesLet $C$ be a convex piece of paper; its boundary may be a smooth curve, or a polygon. A perimeter halving folding is a folding of $C$ obtained by iden...
Edge-Unfolding Polycubes
v1.3 research notesIs there any genus-zero orthogonal polyhedron $P$ built by gluing together cubes face-to-face that cannot be edge-unfolded, where all cube edges on th...
Rolling a Die over a Labeled Board
v1.3 research notesLabel the faces of a unit cube with numbers $1$--$6$ as in a die. Place the cube to sit on an integer lattice grid, with one corner at the origin and ...
Polyhedron with Regular Pentagon Faces
v1.3 research notesLet $M$ be a closed polyhedral surface homeomorphic to $S^2$ which is entirely composed of equal regular pentagons. If $M$ is immersed in 3-space, is ...
Congruent Partitions of Polygons
v1.3 research notesPartition a given polygon $P$ into $n$ mutually congruent pieces so that the area of $P$ not covered by the union of the pieces is as small as possibl...
Slicing Axes-Parallel Rectangles
v1.3 research notesLet us say that two rectangles in the place are independent if both their $x$- and $y$-axis projections are disjoint. A set of rectangles is then inde...
Zipper Unfoldings of Convex Polyhedra
v1.3 research notesDoes every convex polyhedron $P$ have a zipper unfolding? A zipper unfolding cuts open $P$ via a single path, necessarily a Hamiltonian path (to span ...
Rigidity of Smooth Isometric Families of Compact Surfaces
v1.3 research notesLet $M$ be a compact surface, $I=(-1,1)$, and $f:M\times I\to\mathbb{R}^3$ a differentiable map such that each $f_t$ is an immersion and its induced m...
Stability of Spherical Plateau Clusters
v1.3 research notesIs every bubble cluster in $\mathbb{R}^3$ made of spherical pieces meeting according to Plateau's rules necessarily stable, in the sense of having non...