The number of small covers over cubes

The number of orientable small covers over cubes

We count orientable small covers over cubes. We also get estimates for $O_n/R_n$, where $O_n$ is the number of orientable small covers and $R_n$ is the number of all small covers over an $n$-cube up to the Davis-Januszkiewicz equivalence.

Leighton定理与正则立方体复形

Leighton's Theorem and Regular Cube Complexes

本研究将Leighton图覆盖定理推广至一类作为正则图自然推广的非正曲率特殊立方体复形，该类复形涵盖双曲与非双曲的CAT(0)立方体复形，拓展了定理的适用范围。

Small examples of cube diagrams of knots

In this short note we highlight some of the differences between cube diagrams and grid diagrams. We also list examples of small cube diagrams for all knots up to 7 crossings and give some examples of links.

Unravelling the Dodecahedral Spaces

The hyperbolic dodecahedral space of Weber and Seifert has a natural non-positively curved cubulation obtained by subdividing the dodecahedron into cubes. We show that the hyperbolic dodecahedral space has a 6-sheeted irregular cover with the property that the canonical hypersurfaces made up of the mid-cubes give a very short hierarchy. Moreover, we describe a 60-sheeted cover in which the associated cubulation is special. We also describe the natural cubulation and covers of the spherical dodecahedral space (aka Poincaré homology sphere).

Cube number can detect chirality and Legendrian type of knots

For a knot K the cube number is a knot invariant defined to be the smallest n for which there is a cube diagram of size n for K. We will show that the cube number detects chirality in all cases computed thus far, and distinguishes certain legendrian knots.

CAT(0)立方复形接触图的自同构

Automorphisms of contact graphs of ${\rm CAT(0)}$ cube complexes

研究CAT(0)立方复形的自同构群与Hagen接触图的自同构群的等价性，揭示接触图与Kim-Koberda扩展图的差异。