233 research outputs found
Topology of random simplicial complexes: a survey
This expository article is based on a lecture from the Stanford Symposium on
Algebraic Topology: Application and New Directions, held in honor of Gunnar
Carlsson, Ralph Cohen, and Ib Madsen.Comment: After revisions, now 21 pages, 5 figure
IST Austria Thesis
Many methods for the reconstruction of shapes from sets of points produce ordered simplicial complexes, which are collections of vertices, edges, triangles, and their higher-dimensional analogues, called simplices, in which every simplex gets assigned a real value measuring its size. This thesis studies ordered simplicial complexes, with a focus on their topology, which reflects the connectedness of the represented shapes and the presence of holes. We are interested both in understanding better the structure of these complexes, as well as in developing algorithms for applications.
For the Delaunay triangulation, the most popular measure for a simplex is the radius of the smallest empty circumsphere. Based on it, we revisit Alpha and Wrap complexes and experimentally determine their probabilistic properties for random data. Also, we prove the existence of tri-partitions, propose algorithms to open and close holes, and extend the concepts from Euclidean to Bregman geometries
Operators on random hypergraphs and random simplicial complexes
Random hypergraphs and random simplicial complexes have potential
applications in computer science and engineering. Various models of random
hypergraphs and random simplicial complexes on n-points have been studied. Let
L be a simplicial complex. In this paper, we study random sub-hypergraphs and
random sub-complexes of L. By considering the minimal complex that a
sub-hypergraph can be embedded in and the maximal complex that can be embedded
in a sub-hypergraph, we define some operators on the space of probability
functions on sub-hypergraphs of L. We study the compositions of these operators
as well as their actions on the space of probability functions. As applications
in computer science, we give algorithms generating large sparse random
hypergraphs and large sparse random simplicial complexes.Comment: 22 page
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