CW complexes

E911364

CW complexes are topological spaces built by inductively attaching cells of increasing dimension, providing a flexible and combinatorially tractable framework for algebraic topology.

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Label Occurrences
CW complexes canonical 1

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Statements (50)

Predicate Object
instanceOf mathematical structure
topological space
exampleOf cell complex
field algebraic topology NERFINISHED
generalizes finite cell complexes
simplicial complexes
hasProperty 0-skeleton is a discrete set of points
Hausdorff NERFINISHED
admits CW-structure on many familiar spaces
admits cellular approximation of maps
attaching maps determine the CW structure
built from open cells
built inductively by attaching cells
cellular chain complex computes homology
cellular cochain complex computes cohomology
closed under homotopy equivalence up to CW-approximation
closure-finite condition on cells
combinatorially tractable
constructed by attaching n-dimensional cells
countable CW complexes have countably many cells
each cell attached via continuous map from boundary sphere
every CW complex is weakly homotopy equivalent to a simplicial complex under mild conditions
finite CW complexes have finitely many cells
flexible for constructions in topology
good for computing homotopy type
has a filtration by skeleta
locally finite in many applications
n-skeleton is obtained by attaching n-cells to (n-1)-skeleton
subcomplexes are unions of cells
supports Whitehead theorem for CW complexes
supports cellular approximation theorem
supports obstruction theory
weak topology condition on closures of cells
weak topology with respect to its cells
well-behaved with respect to homotopy
introducedBy J. H. C. Whitehead NERFINISHED
introducedIn 20th century
nameExpandsTo closure-finite weak topology complex
typicalExample Eilenberg–MacLane spaces NERFINISHED
Grassmannians with CW structure
classifying spaces of groups
projective spaces with cell structure
spheres with standard cell decomposition
usedIn cellular homology
cohomology theory
homology theory
homotopy groups of spheres
homotopy theory
spectral sequences
stable homotopy theory

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Referenced by (1)

Full triples — surface form annotated when it differs from this entity's canonical label.

Characteristic Classes hasSubject CW complexes