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Every flag complex is a clique complex: given a flag complex, define a graph G on the set of all vertices, where two vertices u,v are adjacent in G iff {u,v} is in the complex (this graph is called the 1-skeleton of the complex). By definition of a flag complex, every set of vertices that are pairwise-connected, is in the complex.
In topology, the Vietoris–Rips complex, also called the Vietoris complex or Rips complex, is a way of forming a topological space from distances in a set of points. It is an abstract simplicial complex that can be defined from any metric space M and distance δ by forming a simplex for every finite set of points that has diameter at most δ.
A simplicial 3-complex. In mathematics, a simplicial complex is a structured set composed of points, line segments, triangles, and their n-dimensional counterparts, called simplices, such that all the faces and intersections of the elements are also included in the set (see illustration).
Download as PDF; Printable version; In other projects ... The dimension of an abstract simplicial complex is defined ... The formula can be found by examining the ...
A simplicial complex that has a sequence of collapses leading to a point is called collapsible. Every collapsible complex is contractible , but the converse is not true. This definition can be extended to CW-complexes and is the basis for the concept of simple-homotopy equivalence .
Formally, a Δ-set is a sequence of sets {} = together with maps : + for each and =,, …, +, that satisfy + = + whenever <.Often, the superscript of is omitted for brevity.. This definition generalizes the notion of a simplicial complex, where the are the sets of n-simplices, and the are the associated face maps, each mapping the -th face of a simplex in + to a simplex in .
In algebraic topology, the Betti numbers are used to distinguish topological spaces based on the connectivity of n-dimensional simplicial complexes.For the most reasonable finite-dimensional spaces (such as compact manifolds, finite simplicial complexes or CW complexes), the sequence of Betti numbers is 0 from some point onward (Betti numbers vanish above the dimension of a space), and they ...
Using simplicial homology example as a model, one can define a singular homology for any topological space X. A chain complex for X is defined by taking C n to be the free abelian group (or free module) whose generators are all continuous maps from n-dimensional simplices into X. The homomorphisms ∂ n arise from the boundary maps of simplices.