Non-collinear point sets with integer distances must be finite, for strictly convex distance functions on the plane, for two-dimensional complete Riemannian manifolds of bounded genus, and for geodesic distance on convex surfaces in 3d.
We show how to determine the outcome of a Schulze method election, from an input consisting of an \(m\times m\) array of pairwise margins of victory, in time \(O(m^2\log m)\). The algorithm uses random pivoting like that of quickselect.
We define a notion of structural entropy of point sets under which a set has low entropy when it can be covered by few disjoint triangles that are either entirely under the hull of the input or presorted, and show that we can find the hull in time sensitive to this entropy. Generalizations of the same technique apply to geometric maxima, lower envelopes, and visibility polygons.
Journals – Publications – David Eppstein – Theory Group – Inf. & Comp. Sci. – UC Irvine
Semi-automatically filtered from a common source file.