Mathematics Problem Archive
Rokhlin multiple-mixing problem
v1.3 research notesIs every strongly mixing measure-preserving transformation strongly mixing of order three?...
Termination of juggler sequences
v1.3 research notesStarting from a positive integer $a_0$, define $a_{n+1}=\lfloor a_n^{1/2}\rfloor$ when $a_n$ is even and $a_{n+1}=\lfloor a_n^{3/2}\rfloor$ when $a_n$...
Completeness of Lyapunov's second method
v1.3 research notesFor which classes of ordinary differential equations do the classical and canonically generalized forms of Lyapunov's second method give necessary as ...
Local reversibility of reversible cellular automata
v1.3 research notesIn every dimension at least three, is each reversible cellular automaton locally reversible?...
Closed-versus-preclosed trajectory lengths
v1.3 research notesIn a regular $n$-gon, call a trajectory preclosed when its endpoints divide their boundary edges into equal-length parts and meet those oriented edges...
Types of vertices of reachable polygons
v1.3 research notesUnfold a billiard trajectory in a regular $n$-gon by reflecting the polygon across each encountered side. A short trajectory joins two vertices and me...
Reachable points lie on reachable polygons
v1.3 research notesUnfold a billiard trajectory in a regular $n$-gon by reflecting the polygon across each encountered side. A short trajectory joins two vertices and me...
Reachable points on lines through a unitary pair
v1.3 research notesUnfold a billiard trajectory in a regular $n$-gon by reflecting the polygon across each encountered side. A short trajectory joins two vertices and me...
Types of parallel short trajectories
v1.3 research notesUnfold a billiard trajectory in a regular $n$-gon by reflecting the polygon across each encountered side. A short trajectory joins two vertices and me...
Length ratios of parallel short trajectories
v1.3 research notesUnfold a billiard trajectory in a regular $n$-gon by reflecting the polygon across each encountered side. A short trajectory joins two vertices and me...
Short geodesics on the regular dodecahedron
v1.3 research notesOn a regular dodecahedron, unfold a geodesic beginning at a vertex $v$ through successive faces. Call it short if it ends at a vertex and meets no ver...
Elliptic-billiard invariant k_{107}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{108}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{110}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{111}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{114}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{115}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{117}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{118}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{120}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{203,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{203,b}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{204}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{303,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{303,b}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{304}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{307}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{401}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{402}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{403,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{403,b}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{404}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{405}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{406,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{406,b}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{407}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{601}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{602}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{603}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{605,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{606}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{607}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{608}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{609}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{610}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{804,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{804,b}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{805}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{806,a}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...
Elliptic-billiard invariant k_{806,b}
v1.3 research notesFix an ellipse with center $O$ and foci $f_1,f_2$, and let $P=(P_i)_{i=1}^N$ range over its Poncelet family of $N$-periodic billiard orbits tangent to...