Mathematics Problem Archive
Accessibility of basin-boundary periodic points
v1.3 research notesLet $f:U\to f(U)$ be a proper holomorphic map of degree at least two on a simply connected attracting basin $U$, and suppose $f$ extends holomorphical...
Accessibility of positive-exponent boundary points
v1.3 research notesIn the setting of Przytycki Problem 1.1, is every $x\in\partial U$ with $\liminf_{n\to\infty}n^{-1}\log|(f^n)'(x)|>0$ accessible from $U$?...
Boundary entropy of an attracting basin
v1.3 research notesIn the setting of Przytycki Problem 1.1, is $h_{\mathrm{top}}(f|_{\partial U})=\log\deg(f|_U)$?...
Dynamics on a Siegel-disk boundary
v1.3 research notesCan the boundary of a Siegel disk contain periodic points or points with positive Lyapunov exponent? Must the topological entropy of the boundary dyna...
Lifting invariant measures through coding trees
v1.3 research notesFor a holomorphic quasi-repeller $\Lambda$, is every invariant ergodic measure on $\overline\Lambda$ the image of a measure on a one-sided shift under...
Limit laws on holomorphic quasi-repellers
v1.3 research notesCharacterize the positive-entropy invariant measures $m$ on a holomorphic quasi-repeller for which the almost-sure invariance principle, law of the it...
Absolute continuity at full dimension
v1.3 research notesFor a positive-entropy invariant measure $m$ on a holomorphic quasi-repeller $\Lambda$, is $m$ absolutely continuous with respect to Hausdorff measure...
Unbounded Jacobian cocycles and singularity
v1.3 research notesFor which positive-entropy invariant measures $m$ does failure of uniform $L^2(m)$ boundedness of the sums of $\log\operatorname{Jac}_m f-\kappa\log|f...
Bounded Jacobian cocycles and absolute continuity
v1.3 research notesFor which positive-entropy invariant measures $m$ does uniform $L^2(m)$ boundedness of the sums of $\log\operatorname{Jac}_m f-\kappa\log|f'|$, where ...
Boundary theorems for geometric coding trees
v1.3 research notesWhich theorems about boundary behavior of Riemann maps have analogues for geometric coding trees?...
Approximating quasi-repeller dimension by measures
v1.3 research notesFor a holomorphic quasi-repeller $\Lambda$, is $\sup_{m\in\mathcal M^+(\Lambda)}\dim_Hm=\dim_H\overline\Lambda$? Does allowing all invariant ergodic m...
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....
Dynamics of exponential-trigonometric entire maps
v1.3 research notesDescribe the dynamics of the entire maps $z\mapsto\lambda e^z\sin z$ and $z\mapsto\lambda e^z\cos z$....
Full-plane Julia sets in the exponential family
v1.3 research notesFor $E_\lambda(z)=\lambda e^z$, characterize completely the parameters $\lambda$ for which $J(E_\lambda)=\mathbb C$....
Smoothness of exponential-family parameter hairs
v1.3 research notesMany parameters with $J(E_\lambda)=\mathbb C$ lie on parameter curves or hairs. Are these hairs $C^\infty$? Are they analytic?...
Homeomorphism type of exponential Knaster continua
v1.3 research notesFor parameters $\lambda,\mu>1/e$, are the Knaster-like continua arising in the dynamics of $E_\lambda(z)=\lambda e^z$ and $E_\mu(z)=\mu e^z$ homeomorp...
Parameter spaces of cosine and sine families
v1.3 research notesDescribe the parameter-space structure for the entire families $C_\lambda(z)=\lambda\cos z$ and $S_\lambda(z)=\lambda\sin z$....
Measure and dimension of transcendental parameter hairs
v1.3 research notesDetermine the measure and Hausdorff dimension of the parameter hairs in the exponential, sine, and cosine families....
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....
Uniform convergence to an irrationally indifferent fixed point
v1.3 research notesLet $\varphi$ be a holomorphic germ fixing $z_0$ with multiplier $e^{2\pi i\alpha}$ for irrational $\alpha$. Can $\varphi^n(z)\to z_0$ uniformly on so...
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-...
Uniform access to roots for relaxed Newton maps
v1.3 research notesLet all roots of a degree-$d$ polynomial $f$ lie in the unit disk, let $\alpha$ be a root of multiplicity $m$, and let $A^*_{h}(\alpha)$ be its immedi...
Expanding conformal metric for nonrecurrent quadratics
v1.3 research notesIf the quadratic polynomial $P_c(z)=z^2+c$ is nonrecurrent, does there exist a conformal metric $\rho(z)|dz|$ with integrable singularities in which $...
Continuous extension of external-ray rotation number
v1.3 research notesFor monic polynomials $z^n+a_{n-1}z^{n-1}+\cdots+a_1z$ with $|a_1|\ge1$, external rays landing at the fixed point $0$ have a rotation number. Does thi...
Convergence of the real Thurston algorithm
v1.3 research notesFor a piecewise monotone interval map, iteratively replace its critical values by those of a polynomial with the same ordered critical data and conjug...
Thurston algorithm for power-law lift families
v1.3 research notesFor the lift family $x\mapsto k-k|2x-1|^\alpha$, $\alpha>1$, does the real Thurston algorithm converge whenever the initial interval map has a periodi...
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....
Wandering stable components for complex Hénon maps
v1.3 research notesLet $f$ be a polynomial diffeomorphism of $\mathbb C^2$ with Jacobian determinant $\delta$, let $U$ be a component of the interior of the bounded-forw...
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...
Dimension and ergodicity of geometrically finite Julia sets
v1.3 research notesFor a geometrically finite rational map $f$, prove that either its Julia set is the whole sphere and $f$ is ergodic there, or its Julia set has Hausdo...
Local connectivity of geometrically finite Julia components
v1.3 research notesProve that every connected component of the Julia set of a geometrically finite rational map is locally connected....
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...
Combinatorial theory for geometrically finite maps
v1.3 research notesExtend Thurston's finite combinatorial classification from critically finite rational maps to all geometrically finite rational maps: give finite topo...
Critically finite maps with hyperbolic postcritical complement
v1.3 research notesFor $n>1$, do there exist nontrivial critically finite rational maps $f:\mathbb P^n\to\mathbb P^n$ whose postcritical hypersurface $V$ has Kobayashi-h...
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 $\mathbb{R}^3$?...
Euclidean Minimum Spanning Tree
v1.3 research notesCan the Euclidean minimum spanning tree (MST) of $n$ points in $\mathbb{R}^d$ be computed in time close to the lower bound of $\Omega(n \log n)$?...
Minimum Euclidean Matching in 2D
v1.3 research notesWhat is the complexity of computing a minimum-cost Euclidean matching for $2n$ points in the plane? The cost of a matching is the total length of the ...
$k$-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?)...
3SUM Hard Problems
v1.3 research notesCan the class of 3SUM hard problems be solved in subquadratic time? These problems can be reduced from the problem of determining whether, given three...
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?...
Output-sensitive Convex Hull in $\mathbb{R}^d$
v1.3 research notesWhat is the best output-sensitive convex hull algorithm for $n$ points in $\mathbb{R}^d$?...
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?...
Vertex $\pi$-Floodlights
v1.3 research notesHow many $\pi$-floodlights are always sufficient to illuminate any polygon of $n$ vertices, with at most one floodlight placed at each vertex? An $\al...
Polygonal Curve Simplification
v1.3 research notesCan an $n$-vertex polygonal curve be simplified in time nearly linear in $n$?...