Concept
Planar graph
2 essays name this object, across 2 fields. What follows is each of them, and the objects they name alongside it.
Every corner pays for itself
Count the corners of any solid, subtract the edges, add the faces. The answer is two. It is two for a cube, for a pyramid, for a football, for anything squashed or stretched — and the number is measuring the shape it is wrapped around rather than the shape itself.
The plane, divided by whoever is nearest
Scatter some points and colour every other point of the plane by which one is closest. The result is a tiling nobody designed, and its dual triangulation has a property that no part of the construction mentions.
Named alongside it
The objects these essays reach for when they reach for this one.
Euler characteristicCircleConvexityDelaunay triangulationDualityGenusGraphNearest neighbourPerpendicular bisectorPolyhedronTilingTopological invariant