Mathematics Problem Archive

Prove that every sphere packing in $\mathbb{R}^3$ whose tangency graph is $\mathbb{Z}^3$ has at most one accumulation point in the one-point compactif...

Let $D_n$ be the source-to-sink first-passage distance in the recursively substituted hierarchical graph whose distances satisfy $D_n\stackrel d=D_{n-...

For the hierarchical first-passage distances $D_n$ satisfying $D_n\stackrel d=D_{n-1}+\min(D'_{n-1},D''_{n-1})$, determine concentration around the me...

On the three-branch hierarchical graph $G_n$ described in Section 9.3, launch external-DLA particles from the sink until a particle settles at the sin...

In the random hierarchical graph obtained by repeatedly replacing a uniformly chosen edge by the fixed three-edge pattern of Section 9.4, let $D_n$ be...

Start from one edge and at each stage replace every edge independently by two edges in series with probability $p$ or two edges in parallel with proba...

Does there exist a mixing random tiling of the Euclidean plane whose law is invariant under rotations and translations, is stationary under a local cl...

For which dimensions $d$ can $\mathbb{R}^d$ be partitioned into pairwise disjoint curves, each of which has the law or geometric regularity of a Brown...

For i.i.d. first-passage percolation on $\mathbb{Z}^2$, prove or disprove that boundary fluctuations have a Tracy–Widom limit and that the variance of...

Prove that natural i.i.d. first-passage-percolation models on $\mathbb{Z}^d$, including exponential edge lengths, almost surely contain no two-sided i...

Run two walks with a common clock on $\mathbb{Z}^d$, each choosing uniformly among neighbors not previously visited by the other walk. Prove that in $...

Take a uniform quadrangulation with $N$ faces conditioned to have genus $CN$, where $0<C<1/4$. Prove that its rooted local limit is the stochastic hyp...

Determine the almost-sure asymptotic growth rate of the effective resistance from the root to graph-distance $r$ in the uniform infinite planar triang...

Let $G$ be a distributional local limit of finite planar graphs. Prove that $p_c^{\mathrm{site}}(G)\ge1/2$ almost surely and that there is no infinite...

On the $n\times n$ grid with a Gaussian free field with no boundary conditions, give every vertex length equal to the exponential of the field. If $\g...

Generate a quadrangulation from $2n$ bits using the Schaeffer bijection and independently resample each bit with probability $\varepsilon$. Determine ...

For every $p\ge4$, determine the joint law of the matrix of pairwise distances among $p$ independent points sampled from the volume measure of the Bro...

Let $G$ be a bounded-degree recurrent planar triangulation with a fixed root. Are there arbitrarily large $r$ and finite domains containing the radius...

Let $(G_n)$ be finite transitive graphs with $|G_n|\to\infty$ and uniformly bounded effective resistances between all vertex pairs. Prove that the lar...

For every $C<\infty$, prove that there is $c=c(C)<1$ such that, for every simple $n$-vertex graph $G$, the probability that simple random walk covers ...

Let $G$ be a bounded-degree triangulation of a disk. Prove that each of the following conditions implies $p_c(G)\le1/2$: $\operatorname{Dim}(G)\ge2$; ...

Let $G$ be a connected quasi-transitive graph and let $p\in(0,1)$. If Bernoulli percolation has more than one infinite cluster almost surely, prove th...

Let $G$ be a planar graph and consider Bernoulli percolation at $p=1/2$. If an infinite open cluster exists almost surely, prove that there are almost...

For a quasi-transitive graph $G$, characterize when Bernoulli percolation has a unique infinite cluster at $p=p_u(G)$. In particular, give necessary a...

On $\mathbb{Z}^d$, start with the origin black and every other vertex white. Repeatedly choose uniformly an edge having one black and one white endpoi...

Let $(X_n)_{n\in\mathbb{Z}}$ be a centered strictly stationary sequence with $\mathbb{E}[X_0^2]<\infty$. For $k\ge1$, define $$\phi_X(k)=\sup_m\sup\bi...

Which hyperbolic $3$–manifolds admit taut foliations? Give an effective procedure to decide if a hyperbolic $3$–manifold admits a taut foliation. For ...

Is there an effective algorithmic procedure to produce and recognize a hyperbolic knot of depth $n$ for any given $n$? What about $\ge n$?...

Given a collection $\mathscr{C}$ of topological or geometric types of surface, what $3$–manifolds admit a taut foliation $\mathscr{F}$ whose leaves ar...

Let $X$ be a vector field on a $3$–manifold. When is there a foliation $\mathscr{F}$ of $M$ transverse to $X$?...

Let $M$ be atoroidal. Is there a natural refinement of the polyhedral structure of the unit ball of the Thurston norm to a polyhedron $\mathscr{P}_\ma...

Generalize the Teichmüller polynomial from the fibered faces of the Thurston norm ball to the other faces (of some possibly generalized polyhedron, pe...

Suppose $\mathscr{F}$ is a taut foliation of $M$. Characterize the space of metrics on $M$ for which $\mathscr{F}$ can be isotoped to consist of minim...

Given a collection of taut foliations $\mathscr{F}_i$ of $M$, what are the obstructions to finding a metric on $M$ for which the $\mathscr{F}_i$ (afte...

How many Reeb components must a foliation of an open $3$–manifold contain?...

What generalizations of the notion of taut foliation make sense on an open $3$–manifold?...

Characterize those essential laminations which contain genuine sublaminations....

Suppose $\Lambda$ is a full genuine lamination; i.e. it has some complementary region which is an ideal polygon bundle over a circle. Suppose $M$ is h...

Suppose $\Lambda$ is a genuine lamination. When can $\Lambda$ be ``filled in'' to a very full lamination $\Lambda'$? Does it help for $M$ to be hyperb...

Are loosesse laminations good for anything? Are leaves of the universal cover of a loosesse lamination properly embedded? If $M$ contains a loosesse l...

Give an example of a lamination in an atoroidal manifold –- perhaps loosesse –- which can never be realized by minimal surfaces for any metric, but wh...

Characterize branched surfaces embedded in $3$–manifolds which can be non–trivially split to a homeomorphic copy of themselves....

Develop a theory of hierarchies for branched surfaces....

Which boundary slopes are realized by essential laminations carried by a fixed taut ideal triangulation? Give an algorithm....

When does a Haken sum operation make sense for a pair of laminations in normal form with respect to a fixed triangulation?...

Let $M$ be a $3$–manifold, and $\Lambda$ an essential lamination. Let $C$ be a cycle representing the fundamental class of $M$. Is there a cycle $C'$ ...

Suppose $\mathscr{B}$ is a branched surface in $M$ which is dual to a taut local orientation. Is there a finite cover of $M$ in which the pullback of ...

Do branched surfaces without sink disks carry automatic laminations?...

Give a useful definition of thin position for an embedded graph $\Gamma \subset M$ with respect to a taut foliation $\mathscr{F}$. If $\Gamma$ is the ...

Suppose $M$ is irreducible. Suppose further that $\pi_1(M)$ admits a nontrivial action on $\mathbb{R}$. When does $M$ admit a taut foliation with a tr...