Mathematics Problem Archive
Pollock's octahedral-number conjecture
v1.3 research notesIs every positive integer expressible as a sum of at most seven octahedral numbers?...
Global Gan–Gross–Prasad conjecture
v1.3 research notesIn the global Gan–Gross–Prasad setting, is nonvanishing of the relevant $H$-period on an irreducible cuspidal automorphic representation equivalent to...
Greenberg's pseudo-null conjecture
v1.3 research notesLet $F$ be totally real, let $\widetilde F$ be the compositum of all $\mathbb Z_p$-extensions of $F$, let $\widetilde L$ be its maximal unramified abe...
Iwasawa mu-invariant conjecture for number fields
v1.3 research notesFor every number field $K$ and every prime $\ell$, does the Iwasawa invariant $\mu_\ell(K)$ vanish?...
Greenberg's p-rationality conjecture
v1.3 research notesFor every odd prime $p$ and every positive integer $t$, does there exist a $p$-rational number field $K$ with $\operatorname{Gal}(K/\mathbb Q)\cong(\m...
Brumer–Stark conjecture
v1.3 research notesFor a finite abelian extension of number fields, does the Brumer–Stark element have the predicted ideal-class annihilation and principalization proper...
Second Hardy–Littlewood zeta-function conjecture
v1.3 research notesFor every $\varepsilon>0$, do constants $T_0(\varepsilon),c(\varepsilon)>0$ exist such that, for $T\geq T_0$ and $H=T^{1/2+\varepsilon}$, the number $...
Probabilistic McMillan theorem in higher dimensions
v1.3 research notesLet $X_t$ be $d$-dimensional Brownian motion starting at the origin, let $D$ be an open subset of $\mathbb{R}^d$ containing the origin, and let $\tau=...
Topology of planar Brownian trace
v1.3 research notesLet $X_t$ be two-dimensional Brownian motion. (i) For every pair $x,y \notin X[0,1]$, is there a Jordan arc $\Gamma$ containing $x$ and $y$ such that ...
Percolation dimension of planar Brownian trace
v1.3 research notesFor a set $B$, define its percolation dimension as the infimum of the Hausdorff dimensions of Jordan arcs $A\subset B$ containing at least two distinc...
Efficient couplings in acute triangles
v1.3 research notesLet $D$ be a triangle whose angles are all strictly less than $\pi/2$, and let $\mu_2>0$ be the second eigenvalue of the Laplacian on $D$ with Neumann...
Convergence of synchronous reflected-Brownian couplings
v1.3 research notesLet $D\subset\mathbb{R}^2$ be a connected open set with smooth boundary, and let $X,Y$ be synchronously coupled reflected Brownian motions in $D$ driv...
Non-extinction of a Fleming–Viot particle model
v1.3 research notesLet $N$ particles move as independent Brownian motions in a bounded connected open set $D\subset\mathbb{R}^d$. Whenever a particle hits the complement...
Are shy couplings necessarily rigid?
v1.3 research notesLet $D\subset\mathbb{R}^d$, $d\ge2$, be bounded, connected, and open. Suppose there are coupled reflected Brownian motions $X_t,Y_t$ in $D$ and $\vare...
Concatenated bounded Brownian pieces
v1.3 research notesFor each $k\in\mathbb{Z}$, let $B^k$ be Brownian motion and $T_k$ a stopping time, with the stopped pieces independent, $0\le T_k<\infty$, and with th...
Do peaks of random labelings repel each other?
v1.3 research notesChoose uniformly a bijective labeling of the vertices of the $n\times n$ discrete square by $1,2,\ldots,n^2$, and call a vertex a peak when all adjace...
Stationary distributions in one dimension
v1.3 research notesFor the exclusion process on $\mathbb{Z}$ with $p(x,y)=p(y-x)$, assume $\sum_x|x|p(x)<\infty$, $\sum_xxp(x)>0$, and $\sum_{x<0}x^2p(x)=\infty$. Does t...
Stationary distributions in higher dimensions
v1.3 research notesOn $\mathbb{Z}^2$, take nearest-neighbor jump probabilities $p_1,q_1,p_2,q_2$ in directions $\pm e_1,\pm e_2$, with $p_1>q_1$ and $p_2>q_2$. If the an...
Exchangeability in the mean-zero exclusion process
v1.3 research notesFor the exclusion process on $\mathbb{Z}^d$ with translation-invariant kernel $p(x,y)=p(y-x)$ and zero mean $\sum_xxp(x)=0$, prove that every stationa...
Negative association for asymmetric exclusion
v1.3 research notesFor nearest-neighbor asymmetric exclusion on $\mathbb{Z}$ with $p(1)=p>q=p(-1)$, start from the deterministic configuration $\cdots11110000\cdots$. Is...
Martingale for practical purposes
v1.3 research notesGive a mathematically useful definition of a process being a 'martingale for practical purposes', so that failure means it is practical to find a stop...
Analytic toy model for a percolation-fragmentation congestion transition
v1.3 research notesFind a simple network-and-demand toy model in which the marginal satisfiability proportion $r(t)$ can be calculated analytically and exhibits the prop...
Universal compression of sparse labeled graphs
v1.3 research notesFor sparse $n$-vertex graphs of average degree $O(1)$ whose vertices have distinct $O(\log n)$-length labels over a finite alphabet, construct univers...
Mixing times for coagulation-fragmentation processes
v1.3 research notesObtain relaxation- and mixing-time bounds for reversible coagulation-fragmentation Markov chains on finite sets in terms of their model parameters....
Low-density lineage limit of coalescing branching random walk
v1.3 research notesFor the two stationary branching-coalescing models on $\mathbb{Z}^3$ described by Aldous, prove that as particle intensity tends to zero the suitably ...
Constrained Ising storage model on a time-varying graph
v1.3 research notesStudy the constrained Ising storage model described on the page when the underlying graph itself changes in time....
Constant-factor online scheduling of subadditive batches
v1.3 research notesTasks arrive as a rate-one Poisson process and have types in $[0,1]$; batch processing time $S$ is monotone and strictly subadditive and type $a$ incu...
Relaxation time of Metropolis chains on Cayley graphs
v1.3 research notesFor the Metropolis chain on a finite Cayley graph with stationary law $\mu(p)$ obtained by stopping random walk at a geometric time, analyze its relax...
Spectral gap of a Bayesian graph Laplacian
v1.3 research notesFor the posterior random weighted graphs $G(t)$ defined from independent Poisson edge counts and flat priors, study the process $\operatorname{gap}(G(...
Sharp phase transition for SIS epidemics on general networks
v1.3 research notesFor sequences of finite weighted networks with vertex recovery rates and stationary SIS infection counts $X^{(n)}_{\theta,\varepsilon}$ satisfying the...
Shortest routes in random proximity networks
v1.3 research notesFor random proximity graphs on a planar Poisson point process, determine rigorous orders of magnitude for the transversal deviation $T_r$ of a shortes...
Mixing of branch rotation and triangulation chains
v1.3 research notesFor both the diagonal-flip chain on triangulations of the regular $n$-gon and the branch-rotation chain on $n$-cladograms, prove that the relaxation t...
Random Eulerian excursion dichotomy on high-dimensional tori
v1.3 research notesOn the bidirected torus $\mathbb{Z}_N^d$ with fixed $d\ge3$, let $b^{(N)},t^{(N)},m^{(N)}$ count excursions of a uniform Eulerian circuit longer than ...
Second-longest Eulerian excursion on the two-dimensional torus
v1.3 research notesFor a uniform Eulerian circuit on the bidirected two-dimensional torus, does $\log L_2^{(N)}/\log N$ converge in distribution to a random variable wit...
Excursion counts in a random Eulerian circuit on a complete graph
v1.3 research notesOn the bidirected complete $n$-vertex graph, is the expected number of length-$i$ excursions in a uniform Eulerian circuit asymptotic to $e^{-i/n}$?...
Shortest Eulerian excursion on the Hamming cube
v1.3 research notesFor a uniform Eulerian circuit on the bidirected Hamming cube $\{0,1\}^d$, determine the asymptotic behavior or distribution of the shortest excursion...
Eulerian-circuit continuum limits and SLE
v1.3 research notesIs there a relation between space-filling $\operatorname{SLE}_\kappa$ for $\kappa>8$ and the conjectural continuum limit of uniform Eulerian circuits ...
Stretch-length exponent in spatial networks
v1.3 research notesImprove the explicit upper and lower bounds for the minimum network length functions $\Psi^{ave}(s)$ and $\Psi^{worst}(s)$, and prove whether there is...
Largest common subcladogram exponents
v1.3 research notesFor two independent random $n$-cladograms, under both the uniform and coalescent distributions, prove $\mathbb{E}C_n=n^{\gamma+o(1)}$ for respective c...
Largest common suborder of two random two-dimensional orders
v1.3 research notesFor two independent coordinatewise partial orders generated by uniform points in the unit square, prove $\mathbb{E}C_n\sim c n^{1/3}$ and establish th...
Percolation criteria for merging planar empires
v1.3 research notesFor continuous-time processes that merge adjacent polygonal planar regions $A,B$ at a geometry-dependent rate $r(A,B)$, give sufficient conditions on ...
Percolation of planar empires at unit merger rate
v1.3 research notesWhen every adjacent pair of planar empires merges at rate $r(A,B)=1$, does percolation occur?...
Unbalanced regimes of the spatial city-growth model
v1.3 research notesFor the city-growth model, prove: (a) if $\alpha>1$, the eventual number of cities $M(\infty)$ is finite almost surely; (b) if $\beta<2\alpha$, the la...
Growth exponents in the balanced city-growth regime
v1.3 research notesIn the balanced regime $0<\alpha<1$ and $\beta>2\alpha$, prove that the upper and lower growth exponents for influence and city population all equal $...
Largest-city growth at alpha=1
v1.3 research notesIf $\alpha=1$ and $\beta>2$, prove $N_{(1)}(t)=t(\log t)^{1-2/\beta+o(1)}$ almost surely....
Stability dichotomy for the associated city dynamical system
v1.3 research notesFor the associated influence-cell dynamical system in general position with positive initial weights, prove that one weight tends to $1$ if $\alpha>1$...
A mathematically natural SIRSN
v1.3 research notesConstruct a scale-invariant random spatial network whose law is mathematically natural, for example with an explicit formula for the distribution of $...
A visually realistic SIRSN
v1.3 research notesConstruct a scale-invariant random spatial network that is visually realistic, in the sense of not looking very different from a real-world road netwo...
Feasible statistic triples for SIRSNs
v1.3 research notesDetermine the set of possible triples $(\Delta=\mathbb{E}D_1,\ell,p(1))$ over all scale-invariant random spatial networks....
Optimal length-route tradeoff for SIRSNs
v1.3 research notesGive quantitative estimates improving the known bound on $\ell^*(\Delta)$, the infimum edge intensity among SIRSNs with mean unit-distance route lengt...