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  2. Retraction (topology) - Wikipedia

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

    In topology, a branch of mathematics, a retraction is a continuous mapping from a topological space into a subspace that preserves the position of all points in that subspace. [1] The subspace is then called a retract of the original space. A deformation retraction is a mapping that captures the idea of continuously shrinking a space into a ...

  3. Algebraic topology - Wikipedia

    en.wikipedia.org/wiki/Algebraic_topology

    Algebraic topology is a branch of mathematics that uses tools from abstract algebra to study topological spaces. The basic goal is to find algebraic invariants that classify topological spaces up to homeomorphism, though usually most classify up to homotopy equivalence. Although algebraic topology primarily uses algebra to study topological ...

  4. Tor functor - Wikipedia

    en.wikipedia.org/wiki/Tor_functor

    Cartan and Eilenberg showed that these constructions are independent of the choice of projective resolution, and that both constructions yield the same Tor groups. [3] Moreover, for a fixed ring R, Tor is a functor in each variable (from R-modules to abelian groups). For a commutative ring R and R-modules A and B, Tor R

  5. Category:Algebraic topology - Wikipedia

    en.wikipedia.org/wiki/Category:Algebraic_topology

    Algebraic topology is a branch of mathematics in which tools from abstract algebra are used to study topological spaces The main article for this category is Algebraic topology . Contents

  6. List of algebraic topology topics - Wikipedia

    en.wikipedia.org/wiki/List_of_algebraic_topology...

    K-theory. Topological K-theory; Adams operation; Algebraic K-theory; Whitehead torsion; Twisted K-theory; Cobordism; Thom space; Suspension functor; Stable homotopy theory; Spectrum (homotopy theory) Morava K-theory; Hodge conjecture; Weil conjectures; Directed algebraic topology

  7. Mapping cylinder - Wikipedia

    en.wikipedia.org/wiki/Mapping_cylinder

    In mathematics, specifically algebraic topology, the mapping cylinder [1] of a continuous function between topological spaces and is the quotient = (([,])) / where the denotes the disjoint union, and ~ is the equivalence relation generated by

  8. CW complex - Wikipedia

    en.wikipedia.org/wiki/CW_complex

    The topology of = is weak topology: a subset is open iff is open for each k-skeleton . In the language of category theory, the topology on X {\displaystyle X} is the direct limit of the diagram X − 1 ↪ X 0 ↪ X 1 ↪ ⋯ {\displaystyle X_{-1}\hookrightarrow X_{0}\hookrightarrow X_{1}\hookrightarrow \cdots } The name "CW" stands for ...

  9. Vietoris–Rips complex - Wikipedia

    en.wikipedia.org/wiki/Vietoris–Rips_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.