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  2. Base (topology) - Wikipedia

    en.wikipedia.org/wiki/Base_(topology)

    The set Γ of all open intervals in forms a basis for the Euclidean topology on .. A non-empty family of subsets of a set X that is closed under finite intersections of two or more sets, which is called a π-system on X, is necessarily a base for a topology on X if and only if it covers X.

  3. Topological data analysis - Wikipedia

    en.wikipedia.org/wiki/Topological_data_analysis

    The Database of Original & Non-Theoretical Uses of Topology (DONUT) is a database of scholarly articles featuring practical applications of topological data analysis to various areas of science. DONUT was started in 2017 by Barbara Giunti, Janis Lazovskis, and Bastian Rieck, [ 126 ] and as of October 2023 currently contains 447 articles. [ 127 ]

  4. General topology - Wikipedia

    en.wikipedia.org/wiki/General_topology

    There are many ways to define a topology on R, the set of real numbers. The standard topology on R is generated by the open intervals. The set of all open intervals forms a base or basis for the topology, meaning that every open set is a union of some collection of sets from the base. In particular, this means that a set is open if there exists ...

  5. Topology - Wikipedia

    en.wikipedia.org/wiki/Topology

    A three-dimensional model of a figure-eight knot.The figure-eight knot is a prime knot and has an Alexander–Briggs notation of 4 1.. Topology (from the Greek words τόπος, 'place, location', and λόγος, 'study') is the branch of mathematics concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling ...

  6. Subspace topology - Wikipedia

    en.wikipedia.org/wiki/Subspace_topology

    In the following, represents the real numbers with their usual topology. The subspace topology of the natural numbers, as a subspace of , is the discrete topology.; The rational numbers considered as a subspace of do not have the discrete topology ({0} for example is not an open set in because there is no open subset of whose intersection with can result in only the singleton {0}).

  7. Lower limit topology - Wikipedia

    en.wikipedia.org/wiki/Lower_limit_topology

    The Sorgenfrey line can thus be used to study right-sided limits: if : is a function, then the ordinary right-sided limit of at (when the codomain carries the standard topology) is the same as the usual limit of at when the domain is equipped with the lower limit topology and the codomain carries the standard topology.

  8. Neighbourhood system - Wikipedia

    en.wikipedia.org/wiki/Neighbourhood_system

    Filters in topology – Use of filters to describe and characterize all basic topological notions and results. Locally convex topological vector space – Vector space with a topology defined by convex open sets; Neighbourhood (mathematics) – Open set containing a given point; Subbase – Collection of subsets that generate a topology

  9. Tychonoff space - Wikipedia

    en.wikipedia.org/wiki/Tychonoff_space

    A space is completely regular if and only if every closed set can be written as the intersection of a family of zero sets in (i.e. the zero sets form a basis for the closed sets of ). A space X {\displaystyle X} is completely regular if and only if the cozero sets of X {\displaystyle X} form a basis for the topology of X . {\displaystyle X.}