The cochain complex of a graded topological representation #
Let M be a topological representation of G whose underlying module carries a ℤ-indexed
family ℳ of submodules, each stable under the action, and let d : M ⟶ M be an equivariant
endomorphism of degree one with d ≫ d = 0. Then the subrepresentations on the pieces ℳ n for
n : ℕ, with the restrictions of d, form a cochain complex of topological representations. This
file performs that assembly.
Constructions such as tensor products and tensor induction are easier to write on a single carrier
than on a family of summands: the total module of a resolution carries one action and one
differential, and a tensor product of such modules again does. Continuous cohomology, on the other
hand, is computed from complexes in TopRep k G indexed by ℕ (TopRep.resolution'), and the
comparison of TopRep.ResolutionContraction takes such a complex as input. This construction
passes from the first description to the second. No decomposition hypothesis on ℳ is needed, and
the pieces in negative degrees are ignored.
This is the counterpart for topological representations of TauCeti.gradedCochainComplex, which
assembles a ℤ-indexed complex of modules from the same kind of data.
Main definitions #
TopRep.gradedCochainComplex: the cochain complex whose degree-nterm is the subrepresentation onℳ nand whose differential is the restriction ofd.TopRep.gradedCochainComplexι: the inclusion of each term intoM.TopRep.gradedCochainComplexRestrict: the linear maps between terms induced by a homogeneous linear endomorphism ofM.TopRep.gradedCochainComplexInvariant: a fixed homogeneous vector ofMas an invariant element of a term.TopRep.gradedCochainComplexLift: the factorization through a term of a morphism intoMwith values in one piece of the grading.TopRep.gradedCochainComplexMap: the chain map induced by a morphism of degree zero commuting with the differentials.TopRep.gradedCochainComplexIso: an isomorphism preserving and detecting degrees induces an isomorphism of complexes when it commutes with the differentials.TopRep.gradedCochainComplexResMap: the chain map from the restricted complex of a graded representation induced by a morphism of degree zero.
Main results #
TopRep.gradedCochainComplex_d_comp_ι: the inclusions intertwine the differential of the complex withd.TopRep.gradedCochainComplex_d_apply: the same statement on an element.TopRep.gradedCochainComplexLift_comp_ι,TopRep.gradedCochainComplexLift_unique: the factorization through a term is characterized by its composite with the inclusion.TopRep.gradedCochainComplex_d_invariant: a fixed homogeneous vector killed bydis an invariant cocycle of the complex.
The cochain complex of a graded topological representation: its degree-n term is the
subrepresentation on the piece ℳ n, with the induced topology, and its differential is the
restriction of the degree-one endomorphism d, which squares to zero.
Instances For
The degree-n term of gradedCochainComplex is the subrepresentation on ℳ n.
The action on a term of gradedCochainComplex is the action of M.
A map into a term of gradedCochainComplex is continuous exactly when it is continuous as a
map into M, since the term carries the topology induced from M.
A morphism into M with values in ℳ n factors through the degree-n term of
gradedCochainComplex.
Instances For
The factorization through a term of gradedCochainComplex evaluates by the original
morphism.
A linear endomorphism f of M of degree q restricts to a linear map from the degree-m
term of gradedCochainComplex to the degree-n term whenever m + q = n. Such maps need not be
equivariant: the contracting homotopies of TopRep.ResolutionContraction are of this form.
Instances For
The restriction of a homogeneous linear endomorphism to the terms of gradedCochainComplex
evaluates by the endomorphism.
The inclusion of the degree-n term of gradedCochainComplex into the graded
representation.
Instances For
The inclusion of a term of gradedCochainComplex is the inclusion of the submodule.
The inclusions of the terms of gradedCochainComplex are injective.
The factorization through a term of gradedCochainComplex, followed by the inclusion, is the
original morphism.
The factorization through a term of gradedCochainComplex, followed by the inclusion, is the
original morphism.
A morphism into a term of gradedCochainComplex is the factorization of its composite with
the inclusion.
The inclusions intertwine the differentials: the differential of gradedCochainComplex
followed by the inclusion is the inclusion followed by d.
The inclusions intertwine the differentials: the differential of gradedCochainComplex
followed by the inclusion is the inclusion followed by d.
The differential of gradedCochainComplex on an element is d applied to it in M.
A vector of ℳ n fixed by G is an invariant element of the degree-n term of
gradedCochainComplex.
Instances For
The invariant element of a term of gradedCochainComplex given by a fixed vector of ℳ n is
that vector.
A fixed vector of ℳ n killed by d is a cocycle of gradedCochainComplex.
A morphism F : M ⟶ M' of graded topological representations, of degree zero and commuting
with the differentials, restricts degree by degree to a chain map between their cochain
complexes. This is the counterpart of TauCeti.gradedCochainComplexMap for topological
representations.
Instances For
The chain map gradedCochainComplexMap F evaluates by F.
An isomorphism preserving and detecting degrees and commuting with the differentials induces an isomorphism of the associated cochain complexes.
Instances For
The induced complex isomorphism applies the original isomorphism in each degree.
The inverse complex isomorphism applies the inverse original isomorphism in each degree.
A morphism F : res φ M ⟶ M' of degree zero commuting with the differentials, from the
restriction of a graded G-representation along φ : H →* G to a graded H-representation,
restricts degree by degree to a chain map from the restriction of the complex of M to the
complex of M'. It is TopRep.gradedCochainComplexMap F on the complex of res φ M, whose terms
are those of the restricted complex.
Instances For
The chain map gradedCochainComplexResMap φ F evaluates by F.