Whitney sum

E285917

The Whitney sum is a construction in differential topology that combines two vector bundles over the same base space into a new vector bundle whose fibers are direct sums of the original fibers.

All labels observed (2)

Label Occurrences
Whitney sum canonical 1
Whitney sum of vector bundles 1

How this entity was disambiguated

Statements (48)

Predicate Object
instanceOf operation on vector bundles
vector bundle construction
alsoKnownAs Whitney sum
surface form: Whitney sum of vector bundles

direct sum of vector bundles
appearsIn construction of stable normal bundles
splitting of exact sequences of vector bundles
theory of tangent and normal bundles
appliesTo complex vector bundles
real vector bundles
topological vector bundles
baseSpacePreserved true
compatibility compatible with pullback along continuous or smooth maps
compatible with restriction of bundles to subspaces
definedOn vector bundles over the same base space
definesOperationOn isomorphism classes of vector bundles over a fixed base
fiberwiseDescription (E ⊕ F)_x = E_x ⊕ F_x for each x in B
field algebraic topology
differential topology
geometry
generalizes direct sum of vector spaces
givesMonoidStructureTo set of isomorphism classes of vector bundles over a base space
hasIdentityElement zero vector bundle
hasInput vector bundle E → B
vector bundle F → B
hasLocalDescription given local trivializations, transition functions are block-diagonal sums
hasOutput vector bundle E ⊕ F → B
isAssociativeUpToIsomorphism true
isCommutativeUpToIsomorphism true
isFunctorial true
namedAfter Hassler Whitney
preservesComplexStructure true
preservesSmoothStructure true
relatedConcept external direct sum of bundles
pullback of vector bundles
tensor product of vector bundles
requiresCondition bundles are of the same category (e.g. smooth, topological, complex)
bundles share the same base space
satisfiesProperty c(E ⊕ F) = c(E) ∪ c(F) for total Chern classes
p(E ⊕ F) = p(E) ∪ p(F) for Pontryagin classes
rank(E ⊕ F) = rank(E) + rank(F)
w(E ⊕ F) = w(E) ∪ w(F) for Stiefel–Whitney classes
symbol
usedIn classification of vector bundles
construction of characteristic classes
construction of topological K-groups
definition of K-theory
stable equivalence of vector bundles

How these facts were elicited

Referenced by (2)

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

Whitney sum alsoKnownAs Whitney sum
this entity surface form: Whitney sum of vector bundles